stage2: actually coerce in coerce_result_ptr at comptime

src/Sema.zig

@@ -1598,11 +1598,37 @@ fn zirCoerceResultPtr(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileE
     // we cannot do it.
     if (try sema.resolveDefinedValue(block, src, ptr)) |ptr_val| {
         if (ptr_val.isComptimeMutablePtr()) {
+            const sentinel_val = try sema.addConstant(pointee_ty, Value.initTag(.unreachable_value));
+            const coerced = try sema.coerce(block, sema.typeOf(ptr).childType(), sentinel_val, src);
+
+            var res_ptr = ptr_val;
+            var cur_val = (try sema.resolveMaybeUndefVal(block, .unneeded, coerced)).?;
+            while (true) switch (cur_val.tag()) {
+                .unreachable_value => break,
+                .opt_payload => {
+                    res_ptr = try Value.Tag.opt_payload_ptr.create(sema.arena, res_ptr);
+                    cur_val = cur_val.castTag(.opt_payload).?.data;
+                },
+                .eu_payload => {
+                    res_ptr = try Value.Tag.eu_payload_ptr.create(sema.arena, res_ptr);
+                    cur_val = cur_val.castTag(.eu_payload).?.data;
+                },
+                else => {
+                    if (std.debug.runtime_safety) {
+                        std.debug.panic("unexpected Value tag for coerce_result_ptr: {s}", .{
+                            cur_val.tag(),
+                        });
+                    } else {
+                        unreachable;
+                    }
+                },
+            };
+
             const ptr_ty = try Type.ptr(sema.arena, .{
                 .pointee_type = pointee_ty,
                 .@"addrspace" = addr_space,
             });
-            return sema.addConstant(ptr_ty, ptr_val);
+            return sema.addConstant(ptr_ty, res_ptr);
         }
     }
 
@@ -1673,7 +1699,7 @@ fn zirCoerceResultPtr(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileE
                 }
             },
         }
-    } else unreachable; // TODO should not need else unreachable
+    }
 }
 
 pub fn analyzeStructDecl(
@@ -16937,7 +16963,6 @@ fn wrapErrorUnionPayload(
     const dest_payload_ty = dest_ty.errorUnionPayload();
     const coerced = try sema.coerce(block, dest_payload_ty, inst, inst_src);
     if (try sema.resolveMaybeUndefVal(block, inst_src, coerced)) |val| {
-        if (val.isUndef()) return sema.addConstUndef(dest_ty);
         return sema.addConstant(dest_ty, try Value.Tag.eu_payload.create(sema.arena, val));
     }
     try sema.requireRuntimeBlock(block, inst_src);

src/type.zig

@@ -3980,7 +3980,7 @@ pub const Type = extern union {
 
     pub fn structFields(ty: Type) Module.Struct.Fields {
         switch (ty.tag()) {
-            .empty_struct => return .{},
+            .empty_struct, .empty_struct_literal => return .{},
             .@"struct" => {
                 const struct_obj = ty.castTag(.@"struct").?.data;
                 assert(struct_obj.haveFieldTypes());
@@ -3996,7 +3996,7 @@ pub const Type = extern union {
                 const struct_obj = ty.castTag(.@"struct").?.data;
                 return struct_obj.fields.count();
             },
-            .empty_struct => return 0,
+            .empty_struct, .empty_struct_literal => return 0,
             .tuple => return ty.castTag(.tuple).?.data.types.len,
             else => unreachable,
         }

test/behavior/cast.zig

@@ -371,7 +371,9 @@ fn testPeerResolveArrayConstSlice(b: bool) !void {
 }
 
 test "implicitly cast from T to anyerror!?T" {
-    if (builtin.zig_backend != .stage1) return error.SkipZigTest; // TODO
+    if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest;
+    if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest;
+    if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest;
 
     try castToOptionalTypeError(1);
     comptime try castToOptionalTypeError(1);
@@ -387,7 +389,7 @@ fn castToOptionalTypeError(z: i32) !void {
 
     const f = z;
     const g: anyerror!?i32 = f;
-    _ = g catch {};
+    _ = try g;
 
     const a = A{ .a = z };
     const b: anyerror!?A = a;

test/behavior/error.zig

@@ -294,10 +294,11 @@ fn quux_1() !i32 {
 }
 
 test "error: Zero sized error set returned with value payload crash" {
-    if (builtin.zig_backend != .stage1) return error.SkipZigTest; // TODO
+    if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest;
+    if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest;
 
-    _ = foo3(0) catch {};
+    _ = try foo3(0);
-    _ = comptime foo3(0) catch {};
+    _ = comptime try foo3(0);
 }
 
 const Error = error{};

test/behavior/struct.zig

@@ -1237,3 +1237,28 @@ test "anon init through error union" {
     try S.doTheTest();
     comptime try S.doTheTest();
 }
+
+test "typed init through error unions and optionals" {
+    if (builtin.zig_backend == .stage1) return error.SkipZigTest;
+    if (builtin.zig_backend != .stage2_llvm) return error.SkipZigTest; // TODO
+
+    const S = struct {
+        a: u32,
+
+        fn foo() anyerror!?anyerror!@This() {
+            return @This(){ .a = 1 };
+        }
+        fn bar() ?anyerror![2]u8 {
+            return [2]u8{ 1, 2 };
+        }
+
+        fn doTheTest() !void {
+            var a = try (try foo()).?;
+            var b = try bar().?;
+            try expect(a.a + b[1] == 3);
+        }
+    };
+
+    try S.doTheTest();
+    comptime try S.doTheTest();
+}