Sema: do not construct nested partial function types

Closes #12616

2 files changed, 19 insertions, 3 deletions

diff --git a/test/behavior/generics.zig b/test/behavior/generics.zig
index d930fb7d27..ba4bca0c1a 100644
--- a/test/behavior/generics.zig
+++ b/test/behavior/generics.zig
@@ -342,3 +342,18 @@ test "generic instantiation of tagged union with only one field" {
     try expect(S.foo(.{ .s = "a" }) == 1);
     try expect(S.foo(.{ .s = "ab" }) == 2);
 }
+
+test "nested generic function" {
+    const S = struct {
+        fn foo(comptime T: type, callback: *const fn (user_data: T) anyerror!void, data: T) anyerror!void {
+            try callback(data);
+        }
+        fn bar(a: u32) anyerror!void {
+            try expect(a == 123);
+        }
+
+        fn g(_: *const fn (anytype) void) void {}
+    };
+    try expect(@typeInfo(@TypeOf(S.g)).Fn.is_generic);
+    try S.foo(u32, S.bar, 123);
+}
diff --git a/test/cases/compile_errors/comptime_parameter_not_declared_as_such.zig b/test/cases/compile_errors/comptime_parameter_not_declared_as_such.zig
index e4d9eed079..008d14f2fc 100644
--- a/test/cases/compile_errors/comptime_parameter_not_declared_as_such.zig
+++ b/test/cases/compile_errors/comptime_parameter_not_declared_as_such.zig
@@ -1,5 +1,6 @@
 fn f(_: anytype) void {}
-fn g(h: *const fn (anytype) void) void {
+const T = *const fn (anytype) void;
+fn g(h: T) void {
     h({});
 }
 pub export fn entry() void {
@@ -19,5 +20,5 @@ pub export fn entry1() void {
 // backend=stage2
 // target=native
 //
-// :2:6: error: parameter of type '*const fn(anytype) void' must be declared comptime
-// :9:34: error: parameter of type 'comptime_int' must be declared comptime
+// :3:6: error: parameter of type '*const fn(anytype) void' must be declared comptime
+// :10:34: error: parameter of type 'comptime_int' must be declared comptime