diff --git a/src/Sema.zig b/src/Sema.zig
index 885cdeb277..edfd1d36e3 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -4109,6 +4109,8 @@ fn validateUnionInit(
         const union_init = try sema.addConstant(union_ty, union_val);
         try sema.storePtr2(block, init_src, union_ptr, init_src, union_init, init_src, .store);
         return;
+    } else if (try sema.typeRequiresComptime(union_ty)) {
+        return sema.failWithNeededComptime(block, field_ptr_data.src(), "initializer of comptime only union must be comptime-known");
     }
 
     const new_tag = try sema.addConstant(tag_ty, tag_val);
@@ -4226,6 +4228,7 @@ fn validateStructInit(
     var first_block_index = block.instructions.items.len;
     var make_runtime = false;
 
+    const require_comptime = try sema.typeRequiresComptime(struct_ty);
     const air_tags = sema.air_instructions.items(.tag);
     const air_datas = sema.air_instructions.items(.data);
 
@@ -4301,6 +4304,9 @@ fn validateStructInit(
                 }
                 if (try sema.resolveMaybeUndefValAllowVariablesMaybeRuntime(bin_op.rhs, &make_runtime)) |val| {
                     field_values[i] = val;
+                } else if (require_comptime) {
+                    const field_ptr_data = sema.code.instructions.items(.data)[field_ptr].pl_node;
+                    return sema.failWithNeededComptime(block, field_ptr_data.src(), "initializer of comptime only struct must be comptime-known");
                 } else {
                     struct_is_comptime = false;
                 }
@@ -5402,7 +5408,7 @@ fn zirExport(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!void
     const options = sema.resolveExportOptions(block, .unneeded, extra.options) catch |err| switch (err) {
         error.NeededSourceLocation => {
             _ = try sema.resolveExportOptions(block, options_src, extra.options);
-            return error.AnalysisFail;
+            unreachable;
         },
         else => |e| return e,
     };
@@ -5429,7 +5435,7 @@ fn zirExportValue(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError
     const options = sema.resolveExportOptions(block, .unneeded, extra.options) catch |err| switch (err) {
         error.NeededSourceLocation => {
             _ = try sema.resolveExportOptions(block, options_src, extra.options);
-            return error.AnalysisFail;
+            unreachable;
         },
         else => |e| return e,
     };
@@ -6512,7 +6518,7 @@ fn analyzeCall(
                         func_ty_info.param_types,
                         func,
                     );
-                    return error.AnalysisFail;
+                    unreachable;
                 },
                 else => |e| return e,
             };
@@ -6674,7 +6680,7 @@ fn analyzeCall(
                             uncasted_arg,
                             opts,
                         );
-                        return error.AnalysisFail;
+                        unreachable;
                     },
                     else => |e| return e,
                 };
@@ -6687,7 +6693,7 @@ fn analyzeCall(
                             uncasted_arg,
                             Module.argSrc(call_src.node_offset.x, sema.gpa, decl, i, bound_arg_src),
                         );
-                        return error.AnalysisFail;
+                        unreachable;
                     },
                     else => |e| return e,
                 };
@@ -6991,7 +6997,7 @@ fn instantiateGenericCall(
                         const decl = sema.mod.declPtr(block.src_decl);
                         const arg_src = Module.argSrc(call_src.node_offset.x, sema.gpa, decl, i, bound_arg_src);
                         _ = try sema.analyzeGenericCallArgVal(block, arg_src, uncasted_args[i]);
-                        return error.AnalysisFail;
+                        unreachable;
                     },
                     else => |e| return e,
                 };
@@ -7174,7 +7180,7 @@ fn instantiateGenericCall(
                             const decl = sema.mod.declPtr(block.src_decl);
                             const arg_src = Module.argSrc(call_src.node_offset.x, sema.gpa, decl, arg_i, bound_arg_src);
                             _ = try sema.resolveConstValue(block, arg_src, arg, "argument to parameter with comptime-only type must be comptime-known");
-                            return error.AnalysisFail;
+                            unreachable;
                         },
                         else => |e| return e,
                     };
@@ -7330,7 +7336,7 @@ fn instantiateGenericCall(
                         new_fn_info,
                         &runtime_i,
                     );
-                    return error.AnalysisFail;
+                    unreachable;
                 },
                 else => |e| return e,
             };
@@ -8417,6 +8423,10 @@ fn funcCommon(
         const param_types = try sema.arena.alloc(Type, block.params.items.len);
         const comptime_params = try sema.arena.alloc(bool, block.params.items.len);
         for (block.params.items) |param, i| {
+            const is_noalias = blk: {
+                const index = std.math.cast(u5, i) orelse break :blk false;
+                break :blk @truncate(u1, noalias_bits >> index) != 0;
+            };
             param_types[i] = param.ty;
             sema.analyzeParameter(
                 block,
@@ -8427,6 +8437,7 @@ fn funcCommon(
                 &is_generic,
                 cc_resolved,
                 has_body,
+                is_noalias,
             ) catch |err| switch (err) {
                 error.NeededSourceLocation => {
                     const decl = sema.mod.declPtr(block.src_decl);
@@ -8439,8 +8450,9 @@ fn funcCommon(
                         &is_generic,
                         cc_resolved,
                         has_body,
+                        is_noalias,
                     );
-                    return error.AnalysisFail;
+                    unreachable;
                 },
                 else => |e| return e,
             };
@@ -8689,6 +8701,7 @@ fn analyzeParameter(
     is_generic: *bool,
     cc: std.builtin.CallingConvention,
     has_body: bool,
+    is_noalias: bool,
 ) !void {
     const requires_comptime = try sema.typeRequiresComptime(param.ty);
     comptime_params[i] = param.is_comptime or requires_comptime;
@@ -8743,6 +8756,9 @@ fn analyzeParameter(
         };
         return sema.failWithOwnedErrorMsg(msg);
     }
+    if (!this_generic and is_noalias and !param.ty.isPtrAtRuntime()) {
+        return sema.fail(block, param_src, "non-pointer parameter declared noalias", .{});
+    }
 }
 
 fn zirParam(
@@ -10633,7 +10649,7 @@ fn zirSwitchBlock(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError
                             const case_src = Module.SwitchProngSrc{ .range = .{ .prong = multi_i, .item = range_i } };
                             const decl = sema.mod.declPtr(case_block.src_decl);
                             try sema.emitBackwardBranch(block, case_src.resolve(sema.gpa, decl, src_node_offset, .none));
-                            return error.AnalysisFail;
+                            unreachable;
                         },
                         else => return err,
                     };
@@ -10669,7 +10685,7 @@ fn zirSwitchBlock(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError
                         const case_src = Module.SwitchProngSrc{ .multi = .{ .prong = multi_i, .item = @intCast(u32, item_i) } };
                         const decl = sema.mod.declPtr(case_block.src_decl);
                         try sema.emitBackwardBranch(block, case_src.resolve(sema.gpa, decl, src_node_offset, .none));
-                        return error.AnalysisFail;
+                        unreachable;
                     },
                     else => return err,
                 };
@@ -11101,10 +11117,8 @@ fn resolveSwitchItemVal(
     } else |err| switch (err) {
         error.NeededSourceLocation => {
             const src = switch_prong_src.resolve(sema.gpa, sema.mod.declPtr(block.src_decl), switch_node_offset, range_expand);
-            return TypedValue{
-                .ty = item_ty,
-                .val = try sema.resolveConstValue(block, src, item, "switch prong values must be comptime-known"),
-            };
+            _ = try sema.resolveConstValue(block, src, item, "switch prong values must be comptime-known");
+            unreachable;
         },
         else => |e| return e,
     }
@@ -11618,6 +11632,21 @@ fn zirShl(
                 });
             }
         }
+        if (rhs_ty.zigTypeTag() == .Vector) {
+            var i: usize = 0;
+            while (i < rhs_ty.vectorLen()) : (i += 1) {
+                if (rhs_val.indexVectorlike(i).compareHetero(.lt, Value.zero, target)) {
+                    return sema.fail(block, rhs_src, "shift by negative amount '{}' at index '{d}'", .{
+                        rhs_val.indexVectorlike(i).fmtValue(scalar_ty, sema.mod),
+                        i,
+                    });
+                }
+            }
+        } else if (rhs_val.compareHetero(.lt, Value.zero, target)) {
+            return sema.fail(block, rhs_src, "shift by negative amount '{}'", .{
+                rhs_val.fmtValue(scalar_ty, sema.mod),
+            });
+        }
     }
 
     const runtime_src = if (maybe_lhs_val) |lhs_val| rs: {
@@ -11787,6 +11816,21 @@ fn zirShr(
                 });
             }
         }
+        if (rhs_ty.zigTypeTag() == .Vector) {
+            var i: usize = 0;
+            while (i < rhs_ty.vectorLen()) : (i += 1) {
+                if (rhs_val.indexVectorlike(i).compareHetero(.lt, Value.zero, target)) {
+                    return sema.fail(block, rhs_src, "shift by negative amount '{}' at index '{d}'", .{
+                        rhs_val.indexVectorlike(i).fmtValue(scalar_ty, sema.mod),
+                        i,
+                    });
+                }
+            }
+        } else if (rhs_val.compareHetero(.lt, Value.zero, target)) {
+            return sema.fail(block, rhs_src, "shift by negative amount '{}'", .{
+                rhs_val.fmtValue(scalar_ty, sema.mod),
+            });
+        }
         if (maybe_lhs_val) |lhs_val| {
             if (lhs_val.isUndef()) {
                 return sema.addConstUndef(lhs_ty);
@@ -14721,7 +14765,9 @@ fn analyzeCmp(
 ) CompileError!Air.Inst.Ref {
     const lhs_ty = sema.typeOf(lhs);
     const rhs_ty = sema.typeOf(rhs);
-    try sema.checkVectorizableBinaryOperands(block, src, lhs_ty, rhs_ty, lhs_src, rhs_src);
+    if (lhs_ty.zigTypeTag() != .Optional and rhs_ty.zigTypeTag() != .Optional) {
+        try sema.checkVectorizableBinaryOperands(block, src, lhs_ty, rhs_ty, lhs_src, rhs_src);
+    }
 
     if (lhs_ty.zigTypeTag() == .Vector and rhs_ty.zigTypeTag() == .Vector) {
         return sema.cmpVector(block, src, lhs, rhs, op, lhs_src, rhs_src);
@@ -15217,12 +15263,17 @@ fn zirTypeInfo(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!Ai
                         try Value.Tag.ty.create(params_anon_decl.arena(), try param_ty.copy(params_anon_decl.arena())),
                     );
 
+                const is_noalias = blk: {
+                    const index = std.math.cast(u5, i) orelse break :blk false;
+                    break :blk @truncate(u1, info.noalias_bits >> index) != 0;
+                };
+
                 const param_fields = try params_anon_decl.arena().create([3]Value);
                 param_fields.* = .{
                     // is_generic: bool,
                     Value.makeBool(is_generic),
                     // is_noalias: bool,
-                    Value.false, // TODO
+                    Value.makeBool(is_noalias),
                     // arg_type: ?type,
                     param_ty_val,
                 };
@@ -17409,7 +17460,7 @@ fn zirStructInitAnon(
             const decl = sema.mod.declPtr(block.src_decl);
             const field_src = Module.initSrc(src.node_offset.x, sema.gpa, decl, runtime_index);
             try sema.requireRuntimeBlock(block, src, field_src);
-            return error.AnalysisFail;
+            unreachable;
         },
         else => |e| return e,
     };
@@ -17474,25 +17525,31 @@ fn zirArrayInit(
     defer gpa.free(resolved_args);
     for (args[1..]) |arg, i| {
         const resolved_arg = try sema.resolveInst(arg);
-        const arg_src = src; // TODO better source location
         const elem_ty = if (array_ty.zigTypeTag() == .Struct)
             array_ty.structFieldType(i)
         else
             array_ty.elemType2();
-        resolved_args[i] = try sema.coerce(block, elem_ty, resolved_arg, arg_src);
+        resolved_args[i] = sema.coerce(block, elem_ty, resolved_arg, .unneeded) catch |err| switch (err) {
+            error.NeededSourceLocation => {
+                const decl = sema.mod.declPtr(block.src_decl);
+                const elem_src = Module.initSrc(src.node_offset.x, sema.gpa, decl, i);
+                _ = try sema.coerce(block, elem_ty, resolved_arg, elem_src);
+                unreachable;
+            },
+            else => return err,
+        };
     }
 
     if (sentinel_val) |some| {
         resolved_args[resolved_args.len - 1] = try sema.addConstant(array_ty.elemType2(), some);
     }
 
-    const opt_runtime_src: ?LazySrcLoc = for (resolved_args) |arg| {
-        const arg_src = src; // TODO better source location
+    const opt_runtime_index: ?u32 = for (resolved_args) |arg, i| {
         const comptime_known = try sema.isComptimeKnown(arg);
-        if (!comptime_known) break arg_src;
+        if (!comptime_known) break @intCast(u32, i);
     } else null;
 
-    const runtime_src = opt_runtime_src orelse {
+    const runtime_index = opt_runtime_index orelse {
         const elem_vals = try sema.arena.alloc(Value, resolved_args.len);
 
         for (resolved_args) |arg, i| {
@@ -17504,7 +17561,15 @@ fn zirArrayInit(
         return sema.addConstantMaybeRef(block, array_ty, array_val, is_ref);
     };
 
-    try sema.requireRuntimeBlock(block, src, runtime_src);
+    sema.requireRuntimeBlock(block, src, .unneeded) catch |err| switch (err) {
+        error.NeededSourceLocation => {
+            const decl = sema.mod.declPtr(block.src_decl);
+            const elem_src = Module.initSrc(src.node_offset.x, sema.gpa, decl, runtime_index);
+            try sema.requireRuntimeBlock(block, src, elem_src);
+            unreachable;
+        },
+        else => return err,
+    };
     try sema.queueFullTypeResolution(array_ty);
 
     if (is_ref) {
@@ -18502,10 +18567,47 @@ fn zirReify(sema: *Sema, block: *Block, extended: Zir.Inst.Extended.InstData, in
                 }
 
                 var buffer: Value.ToTypeBuffer = undefined;
+                const field_ty = try field_type_val.toType(&buffer).copy(new_decl_arena_allocator);
                 gop.value_ptr.* = .{
-                    .ty = try field_type_val.toType(&buffer).copy(new_decl_arena_allocator),
+                    .ty = field_ty,
                     .abi_align = @intCast(u32, (try alignment_val.getUnsignedIntAdvanced(target, sema)).?),
                 };
+
+                if (field_ty.zigTypeTag() == .Opaque) {
+                    const msg = msg: {
+                        const msg = try sema.errMsg(block, src, "opaque types have unknown size and therefore cannot be directly embedded in unions", .{});
+                        errdefer msg.destroy(sema.gpa);
+
+                        try sema.addDeclaredHereNote(msg, field_ty);
+                        break :msg msg;
+                    };
+                    return sema.failWithOwnedErrorMsg(msg);
+                }
+                if (union_obj.layout == .Extern and !try sema.validateExternType(field_ty, .union_field)) {
+                    const msg = msg: {
+                        const msg = try sema.errMsg(block, src, "extern unions cannot contain fields of type '{}'", .{field_ty.fmt(sema.mod)});
+                        errdefer msg.destroy(sema.gpa);
+
+                        const src_decl = sema.mod.declPtr(block.src_decl);
+                        try sema.explainWhyTypeIsNotExtern(msg, src.toSrcLoc(src_decl), field_ty, .union_field);
+
+                        try sema.addDeclaredHereNote(msg, field_ty);
+                        break :msg msg;
+                    };
+                    return sema.failWithOwnedErrorMsg(msg);
+                } else if (union_obj.layout == .Packed and !(validatePackedType(field_ty))) {
+                    const msg = msg: {
+                        const msg = try sema.errMsg(block, src, "packed unions cannot contain fields of type '{}'", .{field_ty.fmt(sema.mod)});
+                        errdefer msg.destroy(sema.gpa);
+
+                        const src_decl = sema.mod.declPtr(block.src_decl);
+                        try sema.explainWhyTypeIsNotPacked(msg, src.toSrcLoc(src_decl), field_ty);
+
+                        try sema.addDeclaredHereNote(msg, field_ty);
+                        break :msg msg;
+                    };
+                    return sema.failWithOwnedErrorMsg(msg);
+                }
             }
 
             if (tag_ty_field_names) |names| {
@@ -18587,21 +18689,25 @@ fn zirReify(sema: *Sema, block: *Block, extended: Zir.Inst.Extended.InstData, in
                 // is_noalias: bool,
                 const arg_is_noalias = arg_val[1].toBool();
                 // arg_type: ?type,
-                const param_type_val = arg_val[2];
+                const param_type_opt_val = arg_val[2];
 
                 if (arg_is_generic) {
                     return sema.fail(block, src, "Type.Fn.Param.is_generic must be false for @Type", .{});
                 }
 
+                const param_type_val = param_type_opt_val.optionalValue() orelse
+                    return sema.fail(block, src, "Type.Fn.Param.arg_type must be non-null for @Type", .{});
+                const param_type = try param_type_val.toType(&buf).copy(sema.arena);
+
                 if (arg_is_noalias) {
-                    noalias_bits = @as(u32, 1) << (std.math.cast(u5, i) orelse
+                    if (!param_type.isPtrAtRuntime()) {
+                        return sema.fail(block, src, "non-pointer parameter declared noalias", .{});
+                    }
+                    noalias_bits |= @as(u32, 1) << (std.math.cast(u5, i) orelse
                         return sema.fail(block, src, "this compiler implementation only supports 'noalias' on the first 32 parameters", .{}));
                 }
 
-                const param_type = param_type_val.optionalValue() orelse
-                    return sema.fail(block, src, "Type.Fn.Param.arg_type must be non-null for @Type", .{});
-
-                param_types[i] = try param_type.toType(&buf).copy(sema.arena);
+                param_types[i] = param_type;
                 comptime_params[i] = false;
             }
 
@@ -18745,13 +18851,60 @@ fn reifyStruct(
         }
 
         var buffer: Value.ToTypeBuffer = undefined;
+        const field_ty = try field_type_val.toType(&buffer).copy(new_decl_arena_allocator);
         gop.value_ptr.* = .{
-            .ty = try field_type_val.toType(&buffer).copy(new_decl_arena_allocator),
+            .ty = field_ty,
             .abi_align = abi_align,
             .default_val = default_val,
             .is_comptime = is_comptime_val.toBool(),
             .offset = undefined,
         };
+
+        if (field_ty.zigTypeTag() == .Opaque) {
+            const msg = msg: {
+                const msg = try sema.errMsg(block, src, "opaque types have unknown size and therefore cannot be directly embedded in structs", .{});
+                errdefer msg.destroy(sema.gpa);
+
+                try sema.addDeclaredHereNote(msg, field_ty);
+                break :msg msg;
+            };
+            return sema.failWithOwnedErrorMsg(msg);
+        }
+        if (field_ty.zigTypeTag() == .NoReturn) {
+            const msg = msg: {
+                const msg = try sema.errMsg(block, src, "struct fields cannot be 'noreturn'", .{});
+                errdefer msg.destroy(sema.gpa);
+
+                try sema.addDeclaredHereNote(msg, field_ty);
+                break :msg msg;
+            };
+            return sema.failWithOwnedErrorMsg(msg);
+        }
+        if (struct_obj.layout == .Extern and !try sema.validateExternType(field_ty, .struct_field)) {
+            const msg = msg: {
+                const msg = try sema.errMsg(block, src, "extern structs cannot contain fields of type '{}'", .{field_ty.fmt(sema.mod)});
+                errdefer msg.destroy(sema.gpa);
+
+                const src_decl = sema.mod.declPtr(block.src_decl);
+                try sema.explainWhyTypeIsNotExtern(msg, src.toSrcLoc(src_decl), field_ty, .struct_field);
+
+                try sema.addDeclaredHereNote(msg, field_ty);
+                break :msg msg;
+            };
+            return sema.failWithOwnedErrorMsg(msg);
+        } else if (struct_obj.layout == .Packed and !(validatePackedType(field_ty))) {
+            const msg = msg: {
+                const msg = try sema.errMsg(block, src, "packed structs cannot contain fields of type '{}'", .{field_ty.fmt(sema.mod)});
+                errdefer msg.destroy(sema.gpa);
+
+                const src_decl = sema.mod.declPtr(block.src_decl);
+                try sema.explainWhyTypeIsNotPacked(msg, src.toSrcLoc(src_decl), field_ty);
+
+                try sema.addDeclaredHereNote(msg, field_ty);
+                break :msg msg;
+            };
+            return sema.failWithOwnedErrorMsg(msg);
+        }
     }
 
     if (layout == .Packed) {
@@ -21544,7 +21697,7 @@ fn zirPrefetch(
     const options = sema.resolvePrefetchOptions(block, .unneeded, extra.rhs) catch |err| switch (err) {
         error.NeededSourceLocation => {
             _ = try sema.resolvePrefetchOptions(block, opts_src, extra.rhs);
-            return error.AnalysisFail;
+            unreachable;
         },
         else => |e| return e,
     };
@@ -21637,7 +21790,7 @@ fn zirBuiltinExtern(
     const options = sema.resolveExternOptions(block, .unneeded, extra.rhs) catch |err| switch (err) {
         error.NeededSourceLocation => {
             _ = try sema.resolveExternOptions(block, options_src, extra.rhs);
-            return error.AnalysisFail;
+            unreachable;
         },
         else => |e| return e,
     };
@@ -24493,7 +24646,7 @@ fn coerceExtra(
                 }
                 if (try sema.resolveMaybeUndefVal(inst)) |val| {
                     const result_val = try val.floatCast(sema.arena, dest_ty, target);
-                    if (!val.eql(result_val, dest_ty, sema.mod)) {
+                    if (!val.eql(result_val, inst_ty, sema.mod)) {
                         return sema.fail(
                             block,
                             inst_src,
@@ -24987,7 +25140,7 @@ const InMemoryCoercionResult = union(enum) {
                 cur = param.child;
             },
             .fn_cc => |cc| {
-                try sema.errNote(block, src, msg, "calling convention {s} cannot cast into calling convention {s}", .{ @tagName(cc.actual), @tagName(cc.wanted) });
+                try sema.errNote(block, src, msg, "calling convention '{s}' cannot cast into calling convention '{s}'", .{ @tagName(cc.actual), @tagName(cc.wanted) });
                 break;
             },
             .fn_return_type => |pair| {
@@ -26842,6 +26995,9 @@ fn coerceCompatiblePtrs(
 ) !Air.Inst.Ref {
     const inst_ty = sema.typeOf(inst);
     if (try sema.resolveMaybeUndefVal(inst)) |val| {
+        if (!val.isUndef() and val.isNull() and !dest_ty.isAllowzeroPtr()) {
+            return sema.fail(block, inst_src, "null pointer casted to type '{}'", .{dest_ty.fmt(sema.mod)});
+        }
         // The comptime Value representation is compatible with both types.
         return sema.addConstant(dest_ty, val);
     }
@@ -30177,7 +30333,7 @@ fn semaStructFields(mod: *Module, struct_obj: *Module.Struct) CompileError!void
                         const tree = try sema.getAstTree(&block_scope);
                         const init_src = containerFieldInitSrcLoc(decl, tree.*, 0, i);
                         _ = try sema.coerce(&block_scope, field.ty, init, init_src);
-                        return error.AnalysisFail;
+                        unreachable;
                     },
                     else => |e| return e,
                 };
@@ -30304,6 +30460,25 @@ fn semaUnionFields(mod: *Module, union_obj: *Module.Union) CompileError!void {
             if (int_tag_ty.zigTypeTag() != .Int and int_tag_ty.zigTypeTag() != .ComptimeInt) {
                 return sema.fail(&block_scope, tag_ty_src, "expected integer tag type, found '{}'", .{int_tag_ty.fmt(sema.mod)});
             }
+
+            if (fields_len > 0) {
+                var field_count_val: Value.Payload.U64 = .{
+                    .base = .{ .tag = .int_u64 },
+                    .data = fields_len - 1,
+                };
+                if (!(try sema.intFitsInType(Value.initPayload(&field_count_val.base), int_tag_ty, null))) {
+                    const msg = msg: {
+                        const msg = try sema.errMsg(&block_scope, tag_ty_src, "specified integer tag type cannot represent every field", .{});
+                        errdefer msg.destroy(sema.gpa);
+                        try sema.errNote(&block_scope, tag_ty_src, msg, "type '{}' cannot fit values in range 0...{d}", .{
+                            int_tag_ty.fmt(sema.mod),
+                            fields_len - 1,
+                        });
+                        break :msg msg;
+                    };
+                    return sema.failWithOwnedErrorMsg(msg);
+                }
+            }
             union_obj.tag_ty = try sema.generateUnionTagTypeNumbered(&block_scope, fields_len, provided_ty, union_obj);
             const enum_obj = union_obj.tag_ty.castTag(.enum_numbered).?.data;
             enum_field_names = &enum_obj.fields;
@@ -30379,7 +30554,7 @@ fn semaUnionFields(mod: *Module, union_obj: *Module.Union) CompileError!void {
         } else .none;
 
         if (enum_value_map) |map| {
-            if (tag_ref != .none) {
+            const copied_val = if (tag_ref != .none) blk: {
                 const tag_src = src; // TODO better source location
                 const coerced = try sema.coerce(&block_scope, int_tag_ty, tag_ref, tag_src);
                 const val = try sema.resolveConstValue(&block_scope, tag_src, coerced, "enum tag value must be comptime-known");
@@ -30387,23 +30562,31 @@ fn semaUnionFields(mod: *Module, union_obj: *Module.Union) CompileError!void {
 
                 // This puts the memory into the union arena, not the enum arena, but
                 // it is OK since they share the same lifetime.
-                const copied_val = try val.copy(decl_arena_allocator);
-                map.putAssumeCapacityContext(copied_val, {}, .{
-                    .ty = int_tag_ty,
-                    .mod = mod,
-                });
-            } else {
+                break :blk try val.copy(decl_arena_allocator);
+            } else blk: {
                 const val = if (last_tag_val) |val|
                     try sema.intAdd(val, Value.one, int_tag_ty)
                 else
                     Value.zero;
                 last_tag_val = val;
 
-                const copied_val = try val.copy(decl_arena_allocator);
-                map.putAssumeCapacityContext(copied_val, {}, .{
-                    .ty = int_tag_ty,
-                    .mod = mod,
-                });
+                break :blk try val.copy(decl_arena_allocator);
+            };
+            const gop = map.getOrPutAssumeCapacityContext(copied_val, .{
+                .ty = int_tag_ty,
+                .mod = mod,
+            });
+            if (gop.found_existing) {
+                const tree = try sema.getAstTree(&block_scope);
+                const field_src = enumFieldSrcLoc(sema.mod.declPtr(block_scope.src_decl), tree.*, src.node_offset.x, field_i);
+                const other_field_src = enumFieldSrcLoc(sema.mod.declPtr(block_scope.src_decl), tree.*, src.node_offset.x, gop.index);
+                const msg = msg: {
+                    const msg = try sema.errMsg(&block_scope, field_src, "enum tag value {} already taken", .{copied_val.fmtValue(int_tag_ty, sema.mod)});
+                    errdefer msg.destroy(gpa);
+                    try sema.errNote(&block_scope, other_field_src, msg, "other occurrence here", .{});
+                    break :msg msg;
+                };
+                return sema.failWithOwnedErrorMsg(msg);
             }
         }
 
diff --git a/src/type.zig b/src/type.zig
index 93e8c4b502..5e6f032798 100644
--- a/src/type.zig
+++ b/src/type.zig
@@ -177,9 +177,10 @@ pub const Type = extern union {
             .Float,
             .ComptimeFloat,
             .ComptimeInt,
-            .Vector, // TODO some vectors require is_equality_cmp==true
             => true,
 
+            .Vector => ty.elemType2().isSelfComparable(is_equality_cmp),
+
             .Bool,
             .Type,
             .Void,
diff --git a/test/cases/compile_errors/bad_alignment_in_implicit_cast_from_array_pointer_to_slice.zig b/test/cases/compile_errors/bad_alignment_in_implicit_cast_from_array_pointer_to_slice.zig
new file mode 100644
index 0000000000..0641d8e3f9
--- /dev/null
+++ b/test/cases/compile_errors/bad_alignment_in_implicit_cast_from_array_pointer_to_slice.zig
@@ -0,0 +1,12 @@
+export fn a() void {
+    var x: [10]u8 = undefined;
+    var y: []align(16) u8 = &x;
+    _ = y;
+}
+
+// error
+// backend=stage2
+// target=native
+//
+// :3:29: error: expected type '[]align(16) u8', found '*[10]u8'
+// :3:29: note: pointer alignment '1' cannot cast into pointer alignment '16'
diff --git a/test/cases/compile_errors/stage1/obj/bad_alignment_type.zig b/test/cases/compile_errors/bad_alignment_type.zig
similarity index 52%
rename from test/cases/compile_errors/stage1/obj/bad_alignment_type.zig
rename to test/cases/compile_errors/bad_alignment_type.zig
index a4d8b7d68f..523ee2491a 100644
--- a/test/cases/compile_errors/stage1/obj/bad_alignment_type.zig
+++ b/test/cases/compile_errors/bad_alignment_type.zig
@@ -8,8 +8,8 @@ export fn entry2() void {
 }
 
 // error
-// backend=stage1
+// backend=stage2
 // target=native
 //
-// tmp.zig:2:20: error: expected type 'u29', found 'bool'
-// tmp.zig:6:19: error: fractional component prevents float value 12.340000 from being casted to type 'u29'
+// :2:20: error: expected type 'u32', found 'bool'
+// :6:19: error: fractional component prevents float value '12.34' from coercion to type 'u32'
diff --git a/test/cases/compile_errors/compare_optional_to_non-optional_with_invalid_types.zig b/test/cases/compile_errors/compare_optional_to_non-optional_with_invalid_types.zig
new file mode 100644
index 0000000000..0339ac034e
--- /dev/null
+++ b/test/cases/compile_errors/compare_optional_to_non-optional_with_invalid_types.zig
@@ -0,0 +1,37 @@
+export fn inconsistentChildType() void {
+    var x: ?i32 = undefined;
+    const y: comptime_int = 10;
+    _ = (x == y);
+}
+export fn optionalToOptional() void {
+    var x: ?i32 = undefined;
+    var y: ?i32 = undefined;
+    _ = (x == y);
+}
+export fn optionalVector() void {
+    var x: ?@Vector(10, i32) = undefined;
+    var y: @Vector(10, i32) = undefined;
+    _ = (x == y);
+}
+export fn optionalVector2() void {
+    var x: ?@Vector(10, i32) = undefined;
+    var y: @Vector(11, i32) = undefined;
+    _ = (x == y);
+}
+export fn invalidChildType() void {
+    var x: ?[3]i32 = undefined;
+    var y: [3]i32 = undefined;
+    _ = (x == y);
+}
+
+// error
+// backend=llvm
+// target=native
+//
+// :4:12: error: incompatible types: '?i32' and 'comptime_int'
+// :4:10: note: type '?i32' here
+// :4:15: note: type 'comptime_int' here
+// :19:12: error: incompatible types: '?@Vector(10, i32)' and '@Vector(11, i32)'
+// :19:10: note: type '?@Vector(10, i32)' here
+// :19:15: note: type '@Vector(11, i32)' here
+// :24:12: error: operator == not allowed for type '?[3]i32'
diff --git a/test/cases/compile_errors/stage1/obj/comptime_implicit_cast_f64_to_f32.zig b/test/cases/compile_errors/comptime_implicit_cast_f64_to_f32.zig
similarity index 53%
rename from test/cases/compile_errors/stage1/obj/comptime_implicit_cast_f64_to_f32.zig
rename to test/cases/compile_errors/comptime_implicit_cast_f64_to_f32.zig
index af5d49c7cb..3e880e5c14 100644
--- a/test/cases/compile_errors/stage1/obj/comptime_implicit_cast_f64_to_f32.zig
+++ b/test/cases/compile_errors/comptime_implicit_cast_f64_to_f32.zig
@@ -5,7 +5,7 @@ export fn entry() void {
 }
 
 // error
-// backend=stage1
+// backend=stage2
 // target=native
 //
-// tmp.zig:3:20: error: cast of value 16777217.000000 to type 'f32' loses information
+// :3:20: error: type 'f32' cannot represent float value '16777217'
diff --git a/test/cases/compile_errors/stage1/obj/error_when_evaluating_return_type.zig b/test/cases/compile_errors/error_when_evaluating_return_type.zig
similarity index 73%
rename from test/cases/compile_errors/stage1/obj/error_when_evaluating_return_type.zig
rename to test/cases/compile_errors/error_when_evaluating_return_type.zig
index 60731740b7..647b51b475 100644
--- a/test/cases/compile_errors/stage1/obj/error_when_evaluating_return_type.zig
+++ b/test/cases/compile_errors/error_when_evaluating_return_type.zig
@@ -11,7 +11,7 @@ export fn entry() void {
 }
 
 // error
-// backend=stage1
+// backend=stage2
 // target=native
 //
-// tmp.zig:2:19: error: expected type 'i32', found 'type'
+// :2:19: error: expected type 'i32', found 'type'
diff --git a/test/cases/compile_errors/stage1/obj/extern_function_pointer_mismatch.zig b/test/cases/compile_errors/extern_function_pointer_mismatch.zig
similarity index 56%
rename from test/cases/compile_errors/stage1/obj/extern_function_pointer_mismatch.zig
rename to test/cases/compile_errors/extern_function_pointer_mismatch.zig
index 888b59a626..f10a3dbdb3 100644
--- a/test/cases/compile_errors/stage1/obj/extern_function_pointer_mismatch.zig
+++ b/test/cases/compile_errors/extern_function_pointer_mismatch.zig
@@ -6,7 +6,8 @@ export fn c(x: i32) i32 {return x + 2;}
 export fn entry() usize { return @sizeOf(@TypeOf(fns)); }
 
 // error
-// backend=stage1
+// backend=stage2
 // target=native
 //
-// tmp.zig:1:37: error: expected type 'fn(i32) i32', found 'fn(i32) callconv(.C) i32'
+// :1:37: error: expected type 'fn(i32) i32', found 'fn(i32) callconv(.C) i32'
+// :1:37: note: calling convention 'C' cannot cast into calling convention 'Unspecified'
diff --git a/test/cases/compile_errors/floatToInt_comptime_safety.zig b/test/cases/compile_errors/floatToInt_comptime_safety.zig
new file mode 100644
index 0000000000..068d8e2d89
--- /dev/null
+++ b/test/cases/compile_errors/floatToInt_comptime_safety.zig
@@ -0,0 +1,17 @@
+comptime {
+    _ = @floatToInt(i8, @as(f32, -129.1));
+}
+comptime {
+    _ = @floatToInt(u8, @as(f32, -1.1));
+}
+comptime {
+    _ = @floatToInt(u8, @as(f32, 256.1));
+}
+
+// error
+// backend=stage2
+// target=native
+//
+// :2:25: error: float value '-129.10000610351562' cannot be stored in integer type 'i8'
+// :5:25: error: float value '-1.100000023841858' cannot be stored in integer type 'u8'
+// :8:25: error: float value '256.1000061035156' cannot be stored in integer type 'u8'
diff --git a/test/cases/compile_errors/stage1/obj/implicit_casting_null_c_pointer_to_zig_pointer.zig b/test/cases/compile_errors/implicit_casting_null_c_pointer_to_zig_pointer.zig
similarity index 60%
rename from test/cases/compile_errors/stage1/obj/implicit_casting_null_c_pointer_to_zig_pointer.zig
rename to test/cases/compile_errors/implicit_casting_null_c_pointer_to_zig_pointer.zig
index 0bd38d868b..b51635ad30 100644
--- a/test/cases/compile_errors/stage1/obj/implicit_casting_null_c_pointer_to_zig_pointer.zig
+++ b/test/cases/compile_errors/implicit_casting_null_c_pointer_to_zig_pointer.zig
@@ -5,7 +5,7 @@ comptime {
 }
 
 // error
-// backend=stage1
+// backend=stage2
 // target=native
 //
-// tmp.zig:3:24: error: null pointer casted to type '*u8'
+// :3:24: error: null pointer casted to type '*u8'
diff --git a/test/cases/compile_errors/implicit_dependency_on_libc.zig b/test/cases/compile_errors/implicit_dependency_on_libc.zig
new file mode 100644
index 0000000000..3ccb57ccb5
--- /dev/null
+++ b/test/cases/compile_errors/implicit_dependency_on_libc.zig
@@ -0,0 +1,10 @@
+extern "c" fn exit(u8) void;
+export fn entry() void {
+    exit(0);
+}
+
+// error
+// backend=stage2
+// target=native-linux
+//
+// :1:8: error: dependency on libc must be explicitly specified in the build command
diff --git a/test/cases/compile_errors/stage1/obj/indexing_a_undefined_slice_at_comptime.zig b/test/cases/compile_errors/indexing_a_undefined_slice_at_comptime.zig
similarity index 51%
rename from test/cases/compile_errors/stage1/obj/indexing_a_undefined_slice_at_comptime.zig
rename to test/cases/compile_errors/indexing_a_undefined_slice_at_comptime.zig
index 70b0c68658..ff6f77c3e4 100644
--- a/test/cases/compile_errors/stage1/obj/indexing_a_undefined_slice_at_comptime.zig
+++ b/test/cases/compile_errors/indexing_a_undefined_slice_at_comptime.zig
@@ -4,7 +4,7 @@ comptime {
 }
 
 // error
-// backend=stage1
+// backend=stage2
 // target=native
 //
-// tmp.zig:3:10: error: index 0 outside slice of size 0
+// :3:10: error: use of undefined value here causes undefined behavior
diff --git a/test/cases/compile_errors/stage1/obj/integer_cast_truncates_bits.zig b/test/cases/compile_errors/integer_cast_truncates_bits.zig
similarity index 51%
rename from test/cases/compile_errors/stage1/obj/integer_cast_truncates_bits.zig
rename to test/cases/compile_errors/integer_cast_truncates_bits.zig
index e8ef418624..82eb6b61cf 100644
--- a/test/cases/compile_errors/stage1/obj/integer_cast_truncates_bits.zig
+++ b/test/cases/compile_errors/integer_cast_truncates_bits.zig
@@ -20,12 +20,12 @@ export fn entry4() void {
 }
 
 // error
-// backend=stage1
+// backend=stage2
 // target=native
 //
-// tmp.zig:3:18: error: cast from 'u16' to 'u8' truncates bits
-// tmp.zig:8:22: error: integer value 300 cannot be coerced to type 'u8'
-// tmp.zig:13:20: error: expected type 'u8', found 'u16'
-// tmp.zig:13:20: note: unsigned 8-bit int cannot represent all possible unsigned 16-bit values
-// tmp.zig:18:25: error: expected type 'u64', found 'i8'
-// tmp.zig:18:25: note: unsigned 64-bit int cannot represent all possible signed 8-bit values
+// :3:31: error: type 'u8' cannot represent integer value '300'
+// :8:22: error: type 'u8' cannot represent integer value '300'
+// :13:20: error: expected type 'u8', found 'u16'
+// :13:20: note: unsigned 8-bit int cannot represent all possible unsigned 16-bit values
+// :18:25: error: expected type 'u64', found 'i8'
+// :18:25: note: unsigned 64-bit int cannot represent all possible signed 8-bit values
diff --git a/test/cases/compile_errors/stage1/obj/issue_4207_coerce_from_non-terminated-slice_to_terminated-pointer.zig b/test/cases/compile_errors/issue_4207_coerce_from_non-terminated-slice_to_terminated-pointer.zig
similarity index 59%
rename from test/cases/compile_errors/stage1/obj/issue_4207_coerce_from_non-terminated-slice_to_terminated-pointer.zig
rename to test/cases/compile_errors/issue_4207_coerce_from_non-terminated-slice_to_terminated-pointer.zig
index d53f7731a0..dc5a709553 100644
--- a/test/cases/compile_errors/stage1/obj/issue_4207_coerce_from_non-terminated-slice_to_terminated-pointer.zig
+++ b/test/cases/compile_errors/issue_4207_coerce_from_non-terminated-slice_to_terminated-pointer.zig
@@ -4,8 +4,9 @@ export fn foo() [*:0]const u8 {
 }
 
 // error
-// backend=stage1
+// backend=stage2
 // target=native
 //
 // :3:18: error: expected type '[*:0]const u8', found '*[64]u8'
-// :3:18: note: destination pointer requires a terminating '0' sentinel
+// :3:18: note: destination pointer requires '0' sentinel
+// :1:18: note: function return type declared here
diff --git a/test/cases/compile_errors/stage1/obj/issue_7810-comptime_slice-len_increment_beyond_bounds.zig b/test/cases/compile_errors/issue_7810-comptime_slice-len_increment_beyond_bounds.zig
similarity index 59%
rename from test/cases/compile_errors/stage1/obj/issue_7810-comptime_slice-len_increment_beyond_bounds.zig
rename to test/cases/compile_errors/issue_7810-comptime_slice-len_increment_beyond_bounds.zig
index c8b2f0b09e..8c014ec191 100644
--- a/test/cases/compile_errors/stage1/obj/issue_7810-comptime_slice-len_increment_beyond_bounds.zig
+++ b/test/cases/compile_errors/issue_7810-comptime_slice-len_increment_beyond_bounds.zig
@@ -1,14 +1,14 @@
 export fn foo_slice_len_increment_beyond_bounds() void {
     comptime {
         var buf_storage: [8]u8 = undefined;
-        var buf: []const u8 = buf_storage[0..];
+        var buf: []u8 = buf_storage[0..];
         buf.len += 1;
         buf[8] = 42;
     }
 }
 
 // error
-// backend=stage1
+// backend=stage2
 // target=native
 //
-// :6:12: error: out of bounds slice
+// :6:16: error: comptime store of index 8 out of bounds of array length 8
diff --git a/test/cases/compile_errors/stage1/obj/lazy_pointer_with_undefined_element_type.zig b/test/cases/compile_errors/lazy_pointer_with_undefined_element_type.zig
similarity index 92%
rename from test/cases/compile_errors/stage1/obj/lazy_pointer_with_undefined_element_type.zig
rename to test/cases/compile_errors/lazy_pointer_with_undefined_element_type.zig
index 733a3ca2dd..bffaa770ec 100644
--- a/test/cases/compile_errors/stage1/obj/lazy_pointer_with_undefined_element_type.zig
+++ b/test/cases/compile_errors/lazy_pointer_with_undefined_element_type.zig
@@ -6,7 +6,7 @@ export fn foo() void {
 }
 
 // error
-// backend=stage1
+// backend=stage2
 // target=native
 //
 // :3:28: error: use of undefined value here causes undefined behavior
diff --git a/test/cases/compile_errors/stage1/obj/missing_result_type_for_phi_node.zig b/test/cases/compile_errors/missing_result_type_for_phi_node.zig
similarity index 56%
rename from test/cases/compile_errors/stage1/obj/missing_result_type_for_phi_node.zig
rename to test/cases/compile_errors/missing_result_type_for_phi_node.zig
index 33bc1d0d9c..c4bd686b01 100644
--- a/test/cases/compile_errors/stage1/obj/missing_result_type_for_phi_node.zig
+++ b/test/cases/compile_errors/missing_result_type_for_phi_node.zig
@@ -6,7 +6,7 @@ export fn entry() void {
 }
 
 // error
-// backend=stage1
+// backend=stage2
 // target=native
 //
-// tmp.zig:5:17: error: integer value 0 cannot be coerced to type 'void'
+// :5:11: error: incompatible types: 'void' and 'comptime_int'
diff --git a/test/cases/compile_errors/stage1/obj/noalias_on_non_pointer_param.zig b/test/cases/compile_errors/noalias_on_non_pointer_param.zig
similarity index 58%
rename from test/cases/compile_errors/stage1/obj/noalias_on_non_pointer_param.zig
rename to test/cases/compile_errors/noalias_on_non_pointer_param.zig
index ca84aca73f..f637013c93 100644
--- a/test/cases/compile_errors/stage1/obj/noalias_on_non_pointer_param.zig
+++ b/test/cases/compile_errors/noalias_on_non_pointer_param.zig
@@ -2,7 +2,7 @@ fn f(noalias x: i32) void { _ = x; }
 export fn entry() void { f(1234); }
 
 // error
-// backend=stage1
+// backend=stage2
 // target=native
 //
-// tmp.zig:1:6: error: noalias on non-pointer parameter
+// :1:6: error: non-pointer parameter declared noalias
diff --git a/test/cases/compile_errors/passing_an_under-aligned_function_pointer.zig b/test/cases/compile_errors/passing_an_under-aligned_function_pointer.zig
new file mode 100644
index 0000000000..3e3500e71f
--- /dev/null
+++ b/test/cases/compile_errors/passing_an_under-aligned_function_pointer.zig
@@ -0,0 +1,14 @@
+export fn entry() void {
+    testImplicitlyDecreaseFnAlign(alignedSmall, 1234);
+}
+fn testImplicitlyDecreaseFnAlign(ptr: *const fn () align(8) i32, answer: i32) void {
+    if (ptr() != answer) unreachable;
+}
+fn alignedSmall() align(4) i32 { return 1234; }
+
+// error
+// backend=stage2
+// target=x86_64-linux
+//
+// :2:35: error: expected type '*const fn() align(8) i32', found '*const fn() align(4) i32'
+// :2:35: note: pointer alignment '4' cannot cast into pointer alignment '8'
diff --git a/test/cases/compile_errors/stage1/obj/reify_type_for_union_with_opaque_field.zig b/test/cases/compile_errors/reify_type_for_union_with_opaque_field.zig
similarity index 67%
rename from test/cases/compile_errors/stage1/obj/reify_type_for_union_with_opaque_field.zig
rename to test/cases/compile_errors/reify_type_for_union_with_opaque_field.zig
index 58cba3cd42..aba11031a4 100644
--- a/test/cases/compile_errors/stage1/obj/reify_type_for_union_with_opaque_field.zig
+++ b/test/cases/compile_errors/reify_type_for_union_with_opaque_field.zig
@@ -13,7 +13,8 @@ export fn entry() usize {
 }
 
 // error
-// backend=stage1
+// backend=stage2
 // target=native
 //
-// tmp.zig:1:25: error: opaque types have unknown size and therefore cannot be directly embedded in unions
+// :1:18: error: opaque types have unknown size and therefore cannot be directly embedded in unions
+// :6:45: note: opaque declared here
diff --git a/test/cases/compile_errors/stage1/obj/runtime_assignment_to_comptime_struct_type.zig b/test/cases/compile_errors/runtime_assignment_to_comptime_struct_type.zig
similarity index 56%
rename from test/cases/compile_errors/stage1/obj/runtime_assignment_to_comptime_struct_type.zig
rename to test/cases/compile_errors/runtime_assignment_to_comptime_struct_type.zig
index 62b09673eb..5949031fb9 100644
--- a/test/cases/compile_errors/stage1/obj/runtime_assignment_to_comptime_struct_type.zig
+++ b/test/cases/compile_errors/runtime_assignment_to_comptime_struct_type.zig
@@ -9,7 +9,8 @@ export fn f() void {
 }
 
 // error
-// backend=stage1
+// backend=stage2
 // target=native
 //
-// tmp.zig:7:23: error: unable to evaluate constant expression
+// :7:30: error: unable to resolve comptime value
+// :7:30: note: initializer of comptime only struct must be comptime-known
diff --git a/test/cases/compile_errors/stage1/obj/runtime_assignment_to_comptime_union_type.zig b/test/cases/compile_errors/runtime_assignment_to_comptime_union_type.zig
similarity index 54%
rename from test/cases/compile_errors/stage1/obj/runtime_assignment_to_comptime_union_type.zig
rename to test/cases/compile_errors/runtime_assignment_to_comptime_union_type.zig
index af13f8b8ce..04e2a97e7a 100644
--- a/test/cases/compile_errors/stage1/obj/runtime_assignment_to_comptime_union_type.zig
+++ b/test/cases/compile_errors/runtime_assignment_to_comptime_union_type.zig
@@ -9,7 +9,8 @@ export fn f() void {
 }
 
 // error
-// backend=stage1
+// backend=stage2
 // target=native
 //
-// tmp.zig:7:23: error: unable to evaluate constant expression
+// :7:30: error: unable to resolve comptime value
+// :7:30: note: initializer of comptime only union must be comptime-known
diff --git a/test/cases/compile_errors/stage1/obj/saturating_shl_assign_does_not_allow_negative_rhs_at_comptime.zig b/test/cases/compile_errors/saturating_shl_assign_does_not_allow_negative_rhs_at_comptime.zig
similarity index 65%
rename from test/cases/compile_errors/stage1/obj/saturating_shl_assign_does_not_allow_negative_rhs_at_comptime.zig
rename to test/cases/compile_errors/saturating_shl_assign_does_not_allow_negative_rhs_at_comptime.zig
index 7b94f8e832..c8e95e3969 100644
--- a/test/cases/compile_errors/stage1/obj/saturating_shl_assign_does_not_allow_negative_rhs_at_comptime.zig
+++ b/test/cases/compile_errors/saturating_shl_assign_does_not_allow_negative_rhs_at_comptime.zig
@@ -6,7 +6,7 @@ export fn a() void {
 }
 
 // error
-// backend=stage1
+// backend=stage2
 // target=native
 //
-// error: shift by negative value -2
+// :4:14: error: shift by negative amount '-2'
diff --git a/test/cases/compile_errors/stage1/obj/saturating_shl_does_not_allow_negative_rhs_at_comptime.zig b/test/cases/compile_errors/saturating_shl_does_not_allow_negative_rhs_at_comptime.zig
similarity index 58%
rename from test/cases/compile_errors/stage1/obj/saturating_shl_does_not_allow_negative_rhs_at_comptime.zig
rename to test/cases/compile_errors/saturating_shl_does_not_allow_negative_rhs_at_comptime.zig
index ac1ce7d3a0..75fdff3a19 100644
--- a/test/cases/compile_errors/stage1/obj/saturating_shl_does_not_allow_negative_rhs_at_comptime.zig
+++ b/test/cases/compile_errors/saturating_shl_does_not_allow_negative_rhs_at_comptime.zig
@@ -3,7 +3,7 @@ export fn a() void {
 }
 
 // error
-// backend=stage1
+// backend=stage2
 // target=native
 //
-// error: shift by negative value -2
+// :2:25: error: shift by negative amount '-2'
diff --git a/test/cases/compile_errors/shift_amount_has_to_be_an_integer_type.zig b/test/cases/compile_errors/shift_amount_has_to_be_an_integer_type.zig
new file mode 100644
index 0000000000..ed6935315b
--- /dev/null
+++ b/test/cases/compile_errors/shift_amount_has_to_be_an_integer_type.zig
@@ -0,0 +1,10 @@
+export fn entry() void {
+    const x = 1 << &@as(u8, 10);
+    _ = x;
+}
+
+// error
+// backend=stage2
+// target=native
+//
+// :2:20: error: expected type 'comptime_int', found '*const u8'
diff --git a/test/cases/compile_errors/stage1/obj/shift_by_negative_comptime_integer.zig b/test/cases/compile_errors/shift_by_negative_comptime_integer.zig
similarity index 52%
rename from test/cases/compile_errors/stage1/obj/shift_by_negative_comptime_integer.zig
rename to test/cases/compile_errors/shift_by_negative_comptime_integer.zig
index 3425cf565e..7d3a740e16 100644
--- a/test/cases/compile_errors/stage1/obj/shift_by_negative_comptime_integer.zig
+++ b/test/cases/compile_errors/shift_by_negative_comptime_integer.zig
@@ -4,7 +4,7 @@ comptime {
 }
 
 // error
-// backend=stage1
+// backend=stage2
 // target=native
 //
-// tmp.zig:2:18: error: shift by negative value -1
+// :2:18: error: shift by negative amount '-1'
diff --git a/test/cases/compile_errors/slice_sentinel_mismatch-1.zig b/test/cases/compile_errors/slice_sentinel_mismatch-1.zig
new file mode 100644
index 0000000000..60d8d9707a
--- /dev/null
+++ b/test/cases/compile_errors/slice_sentinel_mismatch-1.zig
@@ -0,0 +1,11 @@
+export fn entry() void {
+    const y: [:1]const u8 = &[_:2]u8{ 1, 2 };
+    _ = y;
+}
+
+// error
+// backend=stage2
+// target=native
+//
+// :2:29: error: expected type '[:1]const u8', found '*const [2:2]u8'
+// :2:29: note: pointer sentinel '2' cannot cast into pointer sentinel '1'
diff --git a/test/cases/compile_errors/stage1/obj/bad_alignment_in_implicit_cast_from_array_pointer_to_slice.zig b/test/cases/compile_errors/stage1/obj/bad_alignment_in_implicit_cast_from_array_pointer_to_slice.zig
deleted file mode 100644
index 12064bd9ab..0000000000
--- a/test/cases/compile_errors/stage1/obj/bad_alignment_in_implicit_cast_from_array_pointer_to_slice.zig
+++ /dev/null
@@ -1,11 +0,0 @@
-export fn a() void {
-    var x: [10]u8 = undefined;
-    var y: []align(16) u8 = &x;
-    _ = y;
-}
-
-// error
-// backend=stage1
-// target=native
-//
-// tmp.zig:3:30: error: expected type '[]align(16) u8', found '*[10]u8'
diff --git a/test/cases/compile_errors/stage1/obj/compare_optional_to_non-optional_with_invalid_types.zig b/test/cases/compile_errors/stage1/obj/compare_optional_to_non-optional_with_invalid_types.zig
deleted file mode 100644
index 32e1fe9b24..0000000000
--- a/test/cases/compile_errors/stage1/obj/compare_optional_to_non-optional_with_invalid_types.zig
+++ /dev/null
@@ -1,35 +0,0 @@
-export fn inconsistentChildType() void {
-    var x: ?i32 = undefined;
-    const y: comptime_int = 10;
-    _ = (x == y);
-}
-
-export fn optionalToOptional() void {
-    var x: ?i32 = undefined;
-    var y: ?i32 = undefined;
-    _ = (x == y);
-}
-
-export fn optionalVector() void {
-    var x: ?@Vector(10, i32) = undefined;
-    var y: @Vector(10, i32) = undefined;
-    _ = (x == y);
-}
-
-export fn invalidChildType() void {
-    var x: ?[3]i32 = undefined;
-    var y: [3]i32 = undefined;
-    _ = (x == y);
-}
-
-// error
-// backend=stage1
-// target=native
-//
-// :4:12: error: cannot compare types '?i32' and 'comptime_int'
-// :4:12: note: optional child type 'i32' must be the same as non-optional type 'comptime_int'
-// :10:12: error: cannot compare types '?i32' and '?i32'
-// :10:12: note: optional to optional comparison is only supported for optional pointer types
-// :16:12: error: TODO add comparison of optional vector
-// :22:12: error: cannot compare types '?[3]i32' and '[3]i32'
-// :22:12: note: operator not supported for type '[3]i32'
diff --git a/test/cases/compile_errors/stage1/obj/floatToInt_comptime_safety.zig b/test/cases/compile_errors/stage1/obj/floatToInt_comptime_safety.zig
deleted file mode 100644
index 1e5fa746a1..0000000000
--- a/test/cases/compile_errors/stage1/obj/floatToInt_comptime_safety.zig
+++ /dev/null
@@ -1,17 +0,0 @@
-comptime {
-    _ = @floatToInt(i8, @as(f32, -129.1));
-}
-comptime {
-    _ = @floatToInt(u8, @as(f32, -1.1));
-}
-comptime {
-    _ = @floatToInt(u8, @as(f32, 256.1));
-}
-
-// error
-// backend=stage1
-// target=native
-//
-// tmp.zig:2:9: error: integer value '-129' cannot be stored in type 'i8'
-// tmp.zig:5:9: error: integer value '-1' cannot be stored in type 'u8'
-// tmp.zig:8:9: error: integer value '256' cannot be stored in type 'u8'
diff --git a/test/cases/compile_errors/stage1/obj/implicit_casting_too_big_integers_to_C_pointers.zig b/test/cases/compile_errors/stage1/obj/implicit_casting_too_big_integers_to_C_pointers.zig
deleted file mode 100644
index f142540ff6..0000000000
--- a/test/cases/compile_errors/stage1/obj/implicit_casting_too_big_integers_to_C_pointers.zig
+++ /dev/null
@@ -1,16 +0,0 @@
-export fn a() void {
-    var ptr: [*c]u8 = (1 << 64) + 1;
-    _ = ptr;
-}
-export fn b() void {
-    var x: u65 = 0x1234;
-    var ptr: [*c]u8 = x;
-    _ = ptr;
-}
-
-// error
-// backend=stage1
-// target=native
-//
-// tmp.zig:2:33: error: integer value 18446744073709551617 cannot be coerced to type 'usize'
-// tmp.zig:7:23: error: integer type 'u65' too big for implicit @intToPtr to type '[*c]u8'
diff --git a/test/cases/compile_errors/stage1/obj/implicit_dependency_on_libc.zig b/test/cases/compile_errors/stage1/obj/implicit_dependency_on_libc.zig
deleted file mode 100644
index f069f78551..0000000000
--- a/test/cases/compile_errors/stage1/obj/implicit_dependency_on_libc.zig
+++ /dev/null
@@ -1,11 +0,0 @@
-extern "c" fn exit(u8) void;
-export fn entry() void {
-    exit(0);
-}
-
-// error
-// backend=stage1
-// target=native-linux
-// is_test=1
-//
-// tmp.zig:3:5: error: dependency on libc must be explicitly specified in the build command
diff --git a/test/cases/compile_errors/stage1/obj/libc_headers_note.zig b/test/cases/compile_errors/stage1/obj/libc_headers_note.zig
deleted file mode 100644
index c8d9a9cbf3..0000000000
--- a/test/cases/compile_errors/stage1/obj/libc_headers_note.zig
+++ /dev/null
@@ -1,12 +0,0 @@
-const c = @cImport(@cInclude("stdio.h"));
-export fn entry() void {
-    _ = c.printf("hello, world!\n");
-}
-
-// error
-// backend=stage1
-// is_test=1
-// target=native-linux
-//
-// tmp.zig:1:11: error: C import failed
-// tmp.zig:1:11: note: libc headers not available; compilation does not link against libc
diff --git a/test/cases/compile_errors/stage1/obj/passing_an_under-aligned_function_pointer.zig b/test/cases/compile_errors/stage1/obj/passing_an_under-aligned_function_pointer.zig
deleted file mode 100644
index d67bd42a72..0000000000
--- a/test/cases/compile_errors/stage1/obj/passing_an_under-aligned_function_pointer.zig
+++ /dev/null
@@ -1,13 +0,0 @@
-export fn entry() void {
-    testImplicitlyDecreaseFnAlign(alignedSmall, 1234);
-}
-fn testImplicitlyDecreaseFnAlign(ptr: fn () align(8) i32, answer: i32) void {
-    if (ptr() != answer) unreachable;
-}
-fn alignedSmall() align(4) i32 { return 1234; }
-
-// error
-// backend=stage1
-// target=native
-//
-// tmp.zig:2:35: error: expected type 'fn() align(8) i32', found 'fn() align(4) i32'
diff --git a/test/cases/compile_errors/stage1/obj/shift_amount_has_to_be_an_integer_type.zig b/test/cases/compile_errors/stage1/obj/shift_amount_has_to_be_an_integer_type.zig
deleted file mode 100644
index 53794dba1b..0000000000
--- a/test/cases/compile_errors/stage1/obj/shift_amount_has_to_be_an_integer_type.zig
+++ /dev/null
@@ -1,10 +0,0 @@
-export fn entry() void {
-    const x = 1 << &@as(u8, 10);
-    _ = x;
-}
-
-// error
-// backend=stage1
-// target=native
-//
-// tmp.zig:2:21: error: shift amount has to be an integer type, but found '*const u8'
diff --git a/test/cases/compile_errors/stage1/obj/slice_sentinel_mismatch-1.zig b/test/cases/compile_errors/stage1/obj/slice_sentinel_mismatch-1.zig
deleted file mode 100644
index d0c47097da..0000000000
--- a/test/cases/compile_errors/stage1/obj/slice_sentinel_mismatch-1.zig
+++ /dev/null
@@ -1,10 +0,0 @@
-export fn entry() void {
-    const y: [:1]const u8 = &[_:2]u8{ 1, 2 };
-    _ = y;
-}
-
-// error
-// backend=stage1
-// target=native
-//
-// tmp.zig:2:37: error: expected type '[:1]const u8', found '*const [2:2]u8'
diff --git a/test/cases/compile_errors/stage1/obj/union_with_too_small_explicit_signed_tag_type.zig b/test/cases/compile_errors/stage1/obj/union_with_too_small_explicit_signed_tag_type.zig
deleted file mode 100644
index 97f4d48f6b..0000000000
--- a/test/cases/compile_errors/stage1/obj/union_with_too_small_explicit_signed_tag_type.zig
+++ /dev/null
@@ -1,16 +0,0 @@
-const U = union(enum(i2)) {
-    A: u8,
-    B: u8,
-    C: u8,
-    D: u8,
-};
-export fn entry() void {
-    _ = U{ .D = 1 };
-}
-
-// error
-// backend=stage1
-// target=native
-//
-// tmp.zig:1:22: error: specified integer tag type cannot represent every field
-// tmp.zig:1:22: note: type i2 cannot fit values in range 0...3
diff --git a/test/cases/compile_errors/stage1/obj/union_auto-enum_value_already_taken.zig b/test/cases/compile_errors/union_auto-enum_value_already_taken.zig
similarity index 64%
rename from test/cases/compile_errors/stage1/obj/union_auto-enum_value_already_taken.zig
rename to test/cases/compile_errors/union_auto-enum_value_already_taken.zig
index 3b00f95ff9..36b52c96b9 100644
--- a/test/cases/compile_errors/stage1/obj/union_auto-enum_value_already_taken.zig
+++ b/test/cases/compile_errors/union_auto-enum_value_already_taken.zig
@@ -11,8 +11,8 @@ export fn entry() void {
 }
 
 // error
-// backend=stage1
+// backend=stage2
 // target=native
 //
-// tmp.zig:6:9: error: enum tag value 60 already taken
-// tmp.zig:4:9: note: other occurrence here
+// :6:5: error: enum tag value 60 already taken
+// :4:5: note: other occurrence here
diff --git a/test/cases/compile_errors/stage1/obj/union_enum_field_does_not_match_enum.zig b/test/cases/compile_errors/union_enum_field_does_not_match_enum.zig
similarity index 67%
rename from test/cases/compile_errors/stage1/obj/union_enum_field_does_not_match_enum.zig
rename to test/cases/compile_errors/union_enum_field_does_not_match_enum.zig
index 38260091dc..9370207c59 100644
--- a/test/cases/compile_errors/stage1/obj/union_enum_field_does_not_match_enum.zig
+++ b/test/cases/compile_errors/union_enum_field_does_not_match_enum.zig
@@ -15,8 +15,8 @@ export fn entry() void {
 }
 
 // error
-// backend=stage1
+// backend=stage2
 // target=native
 //
-// tmp.zig:10:5: error: enum field not found: 'D'
-// tmp.zig:1:16: note: enum declared here
+// :10:5: error: no field named 'D' in enum 'tmp.Letter'
+// :1:16: note: enum declared here
diff --git a/test/cases/compile_errors/union_with_too_small_explicit_signed_tag_type.zig b/test/cases/compile_errors/union_with_too_small_explicit_signed_tag_type.zig
new file mode 100644
index 0000000000..2de72e2725
--- /dev/null
+++ b/test/cases/compile_errors/union_with_too_small_explicit_signed_tag_type.zig
@@ -0,0 +1,16 @@
+const U = union(enum(i2)) {
+    A: u8,
+    B: u8,
+    C: u8,
+    D: u8,
+};
+export fn entry() void {
+    _ = U{ .D = 1 };
+}
+
+// error
+// backend=stage2
+// target=native
+//
+// :1:22: error: specified integer tag type cannot represent every field
+// :1:22: note: type 'i2' cannot fit values in range 0...3
diff --git a/test/cases/compile_errors/stage1/obj/union_with_too_small_explicit_unsigned_tag_type.zig b/test/cases/compile_errors/union_with_too_small_explicit_unsigned_tag_type.zig
similarity index 50%
rename from test/cases/compile_errors/stage1/obj/union_with_too_small_explicit_unsigned_tag_type.zig
rename to test/cases/compile_errors/union_with_too_small_explicit_unsigned_tag_type.zig
index c1496ade86..de2139b607 100644
--- a/test/cases/compile_errors/stage1/obj/union_with_too_small_explicit_unsigned_tag_type.zig
+++ b/test/cases/compile_errors/union_with_too_small_explicit_unsigned_tag_type.zig
@@ -10,8 +10,8 @@ export fn entry() void {
 }
 
 // error
-// backend=stage1
+// backend=stage2
 // target=native
 //
-// tmp.zig:1:22: error: specified integer tag type cannot represent every field
-// tmp.zig:1:22: note: type u2 cannot fit values in range 0...4
+// :1:22: error: specified integer tag type cannot represent every field
+// :1:22: note: type 'u2' cannot fit values in range 0...4
diff --git a/test/cases/compile_errors/stage1/obj/wrong_function_type.zig b/test/cases/compile_errors/wrong_function_type.zig
similarity index 56%
rename from test/cases/compile_errors/stage1/obj/wrong_function_type.zig
rename to test/cases/compile_errors/wrong_function_type.zig
index 58f4477601..867bdccc1a 100644
--- a/test/cases/compile_errors/stage1/obj/wrong_function_type.zig
+++ b/test/cases/compile_errors/wrong_function_type.zig
@@ -5,7 +5,8 @@ fn c() i32 {return 2;}
 export fn entry() usize { return @sizeOf(@TypeOf(fns)); }
 
 // error
-// backend=stage1
+// backend=stage2
 // target=native
 //
-// tmp.zig:1:28: error: expected type 'fn() void', found 'fn() i32'
+// :1:28: error: expected type 'fn() void', found 'fn() i32'
+// :1:28: note: return type 'i32' cannot cast into return type 'void'