Commit e382e7be2b7a4c40a8db78dca0de38141dad8c67 | zig

Fixes #10797

2 files changed, 14 insertions(+), 3 deletions(-)

lib/std/mem.zig+4-3

 @@ -309,9 +309,7 @@ pub fn zeroes(comptime T: type) T {
             if (comptime meta.containerLayout(T) == .Extern) {
                 // The C language specification states that (global) unions
                 // should be zero initialized to the first named member.
-                var item: T = undefined;
+                return @unionInit(T, info.fields[0].name, zeroes(info.fields[0].field_type));
-                @field(item, info.fields[0].name) = zeroes(@TypeOf(@field(item, info.fields[0].name)));
-                return item;
             }
             @compileError("Can't set a " ++ @typeName(T) ++ " to zero.");
 @@ -417,6 +415,9 @@ test "mem.zeroes" {
     var c = zeroes(C_union);
     try testing.expectEqual(@as(u8, 0), c.a);
+    comptime var comptime_union = zeroes(C_union);
+    try testing.expectEqual(@as(u8, 0), comptime_union.a);
 }
 /// Initializes all fields of the struct with their default value, or zero values if no default value is present.

test/run_translated_c.zig+10

...	@@ -1819,4 +1819,14 @@ pub fn addCases(cases: *tests.RunTranslatedCContext) void {	...	@@ -1819,4 +1819,14 @@ pub fn addCases(cases: *tests.RunTranslatedCContext) void {
1819	\\ return 0;	1819	\\ return 0;
1820	\\}	1820	\\}
1821	, "");	1821	, "");
		1822
		1823	cases.add("Zero-initialization of global union. Issue #10797",
		1824	\\#include <stdlib.h>
		1825	\\union U { int x; double y; };
		1826	\\union U u;
		1827	\\int main(void) {
		1828	\\ if (u.x != 0) abort();
		1829	\\ return 0;
		1830	\\}
		1831	, "");
1822	}	1832	}