Sema: fix return type of generic function is function pointer

also that's one less standalone test and one more behavior test.

src/Sema.zig

@@ -8550,8 +8550,22 @@ fn resolveGenericBody(
     const err = err: {
         // Make sure any nested param instructions don't clobber our work.
         const prev_params = block.params;
+        const prev_no_partial_func_type = sema.no_partial_func_ty;
+        const prev_generic_owner = sema.generic_owner;
+        const prev_generic_call_src = sema.generic_call_src;
+        const prev_generic_call_decl = sema.generic_call_decl;
         block.params = .{};
-        defer block.params = prev_params;
+        sema.no_partial_func_ty = true;
+        sema.generic_owner = .none;
+        sema.generic_call_src = .unneeded;
+        sema.generic_call_decl = .none;
+        defer {
+            block.params = prev_params;
+            sema.no_partial_func_ty = prev_no_partial_func_type;
+            sema.generic_owner = prev_generic_owner;
+            sema.generic_call_src = prev_generic_call_src;
+            sema.generic_call_decl = prev_generic_call_decl;
+        }
 
         const uncasted = sema.resolveBody(block, body, func_inst) catch |err| break :err err;
         const result = sema.coerce(block, dest_ty, uncasted, src) catch |err| break :err err;

test/behavior/generics.zig

@@ -443,3 +443,16 @@ test "generic function passed as comptime argument" {
     };
     try S.doMath(std.math.add, 5, 6);
 }
+
+test "return type of generic function is function pointer" {
+    if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest;
+    if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;
+
+    const S = struct {
+        fn b(comptime T: type) ?*const fn () error{}!T {
+            return null;
+        }
+    };
+
+    try expect(null == S.b(void));
+}

test/standalone.zig

@@ -213,10 +213,6 @@ pub const build_cases = [_]BuildCase{
     //    .build_root = "test/standalone/sigpipe",
     //    .import = @import("standalone/sigpipe/build.zig"),
     //},
-    .{
-        .build_root = "test/standalone/issue_13030",
-        .import = @import("standalone/issue_13030/build.zig"),
-    },
     // TODO restore this test
     //.{
     //    .build_root = "test/standalone/options",

test/standalone/issue_13030/build.zig

@@ -1,24 +0,0 @@
-const std = @import("std");
-const builtin = @import("builtin");
-const CrossTarget = std.zig.CrossTarget;
-
-pub fn build(b: *std.Build) void {
-    const test_step = b.step("test", "Test it");
-    b.default_step = test_step;
-
-    add(b, test_step, .Debug);
-    add(b, test_step, .ReleaseFast);
-    add(b, test_step, .ReleaseSmall);
-    add(b, test_step, .ReleaseSafe);
-}
-
-fn add(b: *std.Build, test_step: *std.Build.Step, optimize: std.builtin.OptimizeMode) void {
-    const obj = b.addObject(.{
-        .name = "main",
-        .root_source_file = .{ .path = "main.zig" },
-        .optimize = optimize,
-        .target = .{},
-    });
-
-    test_step.dependOn(&obj.step);
-}

test/standalone/issue_13030/main.zig

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