Commit 7a8d9af4a94caeb74361c9462cd44a1e4356150b | zig

Pointers to zero-bit types are not zero-bit types so the function should
return something.
Closes #12716

2 files changed, 32 insertions(+), 7 deletions(-)

src/codegen/llvm.zig+4-7

...	...	@@ -9051,7 +9051,7 @@ pub const FuncGen = struct {
9051	9051	}
9052	9052	},
9053	9053	},
9054		.Union => return self.unionFieldPtr(inst, struct_ptr, struct_ty, field_index),
	9054	.Union => return self.unionFieldPtr(inst, struct_ptr, struct_ty),
9055	9055	else => unreachable,
9056	9056	}
9057	9057	}
...	...	@@ -9061,16 +9061,13 @@ pub const FuncGen = struct {
9061	9061	inst: Air.Inst.Index,
9062	9062	union_ptr: *const llvm.Value,
9063	9063	union_ty: Type,
9064		field_index: c_uint,
9065	9064	) !?*const llvm.Value {
9066		const union_obj = union_ty.cast(Type.Payload.Union).?.data;
9067		const field = &union_obj.fields.values()[field_index];
9068	9065	const result_llvm_ty = try self.dg.lowerType(self.air.typeOfIndex(inst));
9069		if (!field.ty.hasRuntimeBitsIgnoreComptime()) {
9070		return null;
9071		}
9072	9066	const target = self.dg.module.getTarget();
9073	9067	const layout = union_ty.unionGetLayout(target);
	9068	if (layout.payload_size == 0) {
	9069	return self.builder.buildBitCast(union_ptr, result_llvm_ty, "");
	9070	}
9074	9071	const payload_index = @boolToInt(layout.tag_align >= layout.payload_align);
9075	9072	const union_field_ptr = self.builder.buildStructGEP(union_ptr, payload_index, "");
9076	9073	return self.builder.buildBitCast(union_field_ptr, result_llvm_ty, "");

test/behavior/union.zig+28

...	...	@@ -1352,3 +1352,31 @@ test "@unionInit uses tag value instead of field index" {
1352	1352	}
1353	1353	try expect(@enumToInt(u) == 255);
1354	1354	}
	1355
	1356	test "union field ptr - zero sized payload" {
	1357	if (builtin.zig_backend == .stage2_c) return error.SkipZigTest; // TODO
	1358	if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
	1359	if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
	1360
	1361	const U = union {
	1362	foo: void,
	1363	bar: void,
	1364	fn bar(_: *void) void {}
	1365	};
	1366	var u: U = .{ .foo = {} };
	1367	U.bar(&u.foo);
	1368	}
	1369
	1370	test "union field ptr - zero sized field" {
	1371	if (builtin.zig_backend == .stage2_c) return error.SkipZigTest; // TODO
	1372	if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
	1373	if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
	1374
	1375	const U = union {
	1376	foo: void,
	1377	bar: u32,
	1378	fn bar(_: *void) void {}
	1379	};
	1380	var u: U = .{ .foo = {} };
	1381	U.bar(&u.foo);
	1382	}