Commit b59428e9f78b1f9f265c0ffdba79b128d77644d2 | zig

author	Andrew Kelley <andrew@ziglang.org> 2022-03-29 16:56:12-07:00
committer	Andrew Kelley <andrew@ziglang.org> 2022-03-29 16:56:12-07:00
log	b59428e9f78b1f9f265c0ffdba79b128d77644d2
tree	c6a9a066eee45fc5ca3009e3b8bcf1f219adbd83
parent	12e1304805cbe132d17b31bac2e8123869007e4d

Sema: adjust coercion of undefined error union payload

To no longer set the error code to undefined. This fixes the problem
where an undefined single-item pointer coerced to an error union of a
slice set the whole thing to undefined even though the sub-coercion to
the slice would have produced a defined value.

2 files changed, 10 insertions(+), 5 deletions(-)

src
- Sema.zig
test
- behavior
  - cast.zig

src/Sema.zig-5

 @@ -18140,11 +18140,6 @@ fn coerce(
                 return sema.addConstUndef(dest_ty);
             },
             else => {
-                // undefined sets the error code also to undefined.
-                if (is_undef) {
-                    return sema.addConstUndef(dest_ty);
-                }
                 // T to E!T
                 return sema.wrapErrorUnionPayload(block, dest_ty, inst, inst_src);
             },

test/behavior/cast.zig+10

...	@@ -1372,3 +1372,13 @@ test "cast compatible optional types" {	...	@@ -1372,3 +1372,13 @@ test "cast compatible optional types" {
1372	var b: ?[]const u8 = a;	1372	var b: ?[]const u8 = a;
1373	try expect(b == null);	1373	try expect(b == null);
1374	}	1374	}
		1375
		1376	test "coerce undefined single-item pointer of array to error union of slice" {
		1377	if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
		1378	if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
		1379
		1380	const a = @as([*]u8, undefined)[0..0];
		1381	var b: error{a}![]const u8 = a;
		1382	const s = try b;
		1383	try expect(s.len == 0);
		1384	}