@deprecated: remove per-module flag in Build

This implementation looks at the builder of each
module in the build graph instead of storing a
boolean for each module.

lib/std/Build.zig

@@ -94,7 +94,7 @@ available_deps: AvailableDeps,
 
 release_mode: ReleaseMode,
 
-// True only for the top-level builder.
+/// `true` only for the root `Build`; `false` for any `Build` belonging to a dependency.
 is_root: bool = false,
 
 pub const ReleaseMode = enum {

lib/std/Build/Module.zig

@@ -25,7 +25,6 @@ stack_check: ?bool,
 sanitize_c: ?bool,
 sanitize_thread: ?bool,
 fuzz: ?bool,
-allow_deprecated: ?bool,
 code_model: std.builtin.CodeModel,
 valgrind: ?bool,
 pic: ?bool,
@@ -285,7 +284,6 @@ pub fn init(
                 .owner = owner,
                 .root_source_file = if (options.root_source_file) |lp| lp.dupe(owner) else null,
                 .import_table = .{},
-                .allow_deprecated = owner.graph.allow_deprecated orelse !owner.is_root,
                 .resolved_target = options.target,
                 .optimize = options.optimize,
                 .link_libc = options.link_libc,
@@ -560,7 +558,8 @@ pub fn appendZigProcessFlags(
     try addFlag(zig_args, m.red_zone, "-mred-zone", "-mno-red-zone");
 
     if (m.root_source_file != null) {
-        try addFlag(zig_args, m.allow_deprecated, "-fallow-deprecated", "-fno-allow-deprecated");
+        const allow_deprecated = m.owner.graph.allow_deprecated orelse !m.owner.is_root;
+        try addFlag(zig_args, allow_deprecated, "-fallow-deprecated", "-fno-allow-deprecated");
     }
 
     if (m.dwarf_format) |dwarf_format| {

lib/std/zig/Zir.zig

@@ -4313,7 +4313,6 @@ fn findTrackableInner(
                 .value_placeholder => unreachable,
 
                 // Once again, we start with the boring tags.
-                .deprecated,
                 .this,
                 .ret_addr,
                 .builtin_src,
@@ -4367,6 +4366,7 @@ fn findTrackableInner(
                 .tuple_decl,
                 .dbg_empty_stmt,
                 .astgen_error,
+                .deprecated,
                 => return,
 
                 // `@TypeOf` has a body.

test/cases/compile_errors/deprecated.zig

@@ -0,0 +1,9 @@
+const bad = @deprecated(42);
+
+pub export fn foo() usize {
+    return bad;
+}
+
+// error
+//
+// :1:13: error: found deprecated code

test/compile_errors.zig

@@ -250,18 +250,4 @@ pub fn addCases(ctx: *Cases, b: *std.Build) !void {
             ":1:5: error: expected expression, found 'invalid token'",
         });
     }
-
-    {
-        const case = ctx.obj("usage of deprecated code", b.graph.host);
-
-        case.addError(
-            \\const bad = @deprecated(42);
-            \\
-            \\pub export fn foo() usize {
-            \\   return bad; 
-            \\}
-        , &[_][]const u8{
-            ":1:13: error: found deprecated code",
-        });
-    }
 }

test/tests.zig

@@ -1199,13 +1199,13 @@ pub fn addCliTests(b: *std.Build) *Step {
                 \\}
             ;
 
-            var src_dir = std.fs.cwd().makeOpenPath(b.pathJoin(&.{ tmp_path, "src" }), .{}) catch unreachable;
+            var src_dir = std.fs.cwd().makeOpenPath(b.pathJoin(&.{ tmp_path, "src" }), .{}) catch @panic("unable to create tmp path");
             defer src_dir.close();
 
-            var main = src_dir.createFile("main.zig", .{}) catch unreachable;
+            var main = src_dir.createFile("main.zig", .{}) catch @panic("unable to create main.zig");
             defer main.close();
 
-            main.writeAll(new_main_src) catch unreachable;
+            main.writeAll(new_main_src) catch @panic("unable to write to main.zig");
         }
 
         const init_exe = b.addSystemCommand(&.{ b.graph.zig_exe, "init" });