Merge pull request #13032 from jacobly0/br-on-undef-val

stage2: fix branches on undefined values

src/Module.zig

@@ -4430,6 +4430,8 @@ pub fn semaFile(mod: *Module, file: *File) SemaError!void {
     new_decl.has_linksection_or_addrspace = false;
     new_decl.ty = ty_ty;
     new_decl.val = struct_val;
+    new_decl.@"align" = 0;
+    new_decl.@"linksection" = null;
     new_decl.has_tv = true;
     new_decl.owns_tv = true;
     new_decl.alive = true; // This Decl corresponds to a File and is therefore always alive.

src/Sema.zig

@@ -8107,6 +8107,13 @@ fn funcCommon(
         for (comptime_params) |ct| is_generic = is_generic or ct;
         is_generic = is_generic or ret_ty_requires_comptime;
 
+        if (!is_generic and sema.wantErrorReturnTracing(return_type)) {
+            // Make sure that StackTrace's fields are resolved so that the backend can
+            // lower this fn type.
+            const unresolved_stack_trace_ty = try sema.getBuiltinType(block, ret_ty_src, "StackTrace");
+            _ = try sema.resolveTypeFields(block, ret_ty_src, unresolved_stack_trace_ty);
+        }
+
         break :fn_ty try Type.Tag.function.create(sema.arena, .{
             .param_types = param_types,
             .comptime_params = comptime_params.ptr,
@@ -15631,7 +15638,7 @@ fn zirRetLoad(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!Zir
         return sema.analyzeRet(block, operand, src);
     }
 
-    if (sema.wantErrorReturnTracing()) {
+    if (sema.wantErrorReturnTracing(sema.fn_ret_ty)) {
         const is_non_err = try sema.analyzePtrIsNonErr(block, src, ret_ptr);
         return retWithErrTracing(sema, block, src, is_non_err, .ret_load, ret_ptr);
     }
@@ -15698,11 +15705,11 @@ fn retWithErrTracing(
     return always_noreturn;
 }
 
-fn wantErrorReturnTracing(sema: *Sema) bool {
+fn wantErrorReturnTracing(sema: *Sema, fn_ret_ty: Type) bool {
     // TODO implement this feature in all the backends and then delete this check.
     const backend_supports_error_return_tracing = sema.mod.comp.bin_file.options.use_llvm;
 
-    return sema.fn_ret_ty.isError() and
+    return fn_ret_ty.isError() and
         sema.mod.comp.bin_file.options.error_return_tracing and
         backend_supports_error_return_tracing;
 }
@@ -15754,7 +15761,7 @@ fn analyzeRet(
 
     try sema.resolveTypeLayout(block, src, sema.fn_ret_ty);
 
-    if (sema.wantErrorReturnTracing()) {
+    if (sema.wantErrorReturnTracing(sema.fn_ret_ty)) {
         // Avoid adding a frame to the error return trace in case the value is comptime-known
         // to be not an error.
         const is_non_err = try sema.analyzeIsNonErr(block, src, operand);

src/codegen/llvm.zig

@@ -2332,10 +2332,13 @@ pub const Object = struct {
         // buffer is only used for int_type, `builtin` is a struct.
         const builtin_ty = mod.declPtr(builtin_decl).val.toType(undefined);
         const builtin_namespace = builtin_ty.getNamespace().?;
-        const stack_trace_decl = builtin_namespace.decls
+        const stack_trace_decl_index = builtin_namespace.decls
             .getKeyAdapted(stack_trace_str, Module.DeclAdapter{ .mod = mod }).?;
+        const stack_trace_decl = mod.declPtr(stack_trace_decl_index);
 
-        return mod.declPtr(stack_trace_decl).val.toType(undefined);
+        // Sema should have ensured that StackTrace was analyzed.
+        assert(stack_trace_decl.has_tv);
+        return stack_trace_decl.val.toType(undefined);
     }
 };
 

test/standalone.zig

@@ -97,4 +97,6 @@ pub fn addCases(cases: *tests.StandaloneContext) void {
     // Disabled due to tripping LLVM 13 assertion:
     // https://github.com/ziglang/zig/issues/12015
     //cases.add("tools/update_spirv_features.zig");
+
+    cases.addBuildFile("test/standalone/issue_13030/build.zig", .{ .build_modes = true });
 }

test/standalone/issue_13030/build.zig

@@ -0,0 +1,18 @@
+const std = @import("std");
+const builtin = @import("builtin");
+const Builder = std.build.Builder;
+const CrossTarget = std.zig.CrossTarget;
+
+pub fn build(b: *Builder) void {
+    const mode = b.standardReleaseOptions();
+    const target = b.standardTargetOptions(.{});
+
+    const obj = b.addObject("main", "main.zig");
+    obj.setBuildMode(mode);
+
+    obj.setTarget(target);
+    b.default_step.dependOn(&obj.step);
+
+    const test_step = b.step("test", "Test the program");
+    test_step.dependOn(&obj.step);
+}

test/standalone/issue_13030/main.zig

@@ -0,0 +1,7 @@
+fn b(comptime T: type) ?*const fn () error{}!T {
+    return null;
+}
+
+export fn entry() void {
+    _ = b(void);
+}