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disallow '_' prong when switching on non-exhaustive tagged union

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A tagged union cannot legally be initiated to an invalid enumeration
This commit is contained in:
Vexu
2020-07-27 18:04:08 +03:00
parent 65185016f1
commit 1e835e0fcc
3 changed files with 64 additions and 7 deletions
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32
test/compile_errors.zig
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@@ -51,6 +51,23 @@ pub fn addCases(cases: *tests.CompileErrorContext) void {
"tmp.zig:17:23: error: cannot adjust alignment of zero sized type 'fn(u32) anytype'",
});
cases.addTest("switching with exhaustive enum has '_' prong ",
\\const E = enum{
\\ a,
\\ b,
\\};
\\pub export fn entry() void {
\\ var e: E = .b;
\\ switch (e) {
\\ .a => {},
\\ .b => {},
\\ _ => {},
\\ }
\\}
, &[_][]const u8{
"tmp.zig:7:5: error: switch on exhaustive enum has `_` prong",
});
cases.addTest("invalid pointer with @Type",
\\export fn entry() void {
\\ _ = @Type(.{ .Pointer = .{
@@ -564,6 +581,10 @@ pub fn addCases(cases: *tests.CompileErrorContext) void {
\\ b,
\\ _,
\\};
\\const U = union(E) {
\\ a: i32,
\\ b: u32,
\\};
\\pub export fn entry() void {
\\ var e: E = .b;
\\ switch (e) { // error: switch not handling the tag `b`
@@ -574,10 +595,17 @@ pub fn addCases(cases: *tests.CompileErrorContext) void {
\\ .a => {},
\\ .b => {},
\\ }
\\ var u = U{.a = 2};
\\ switch (u) { // error: `_` prong not allowed when switching on tagged union
\\ .a => {},
\\ .b => {},
\\ _ => {},
\\ }
\\}
, &[_][]const u8{
"tmp.zig:8:5: error: enumeration value 'E.b' not handled in switch",
"tmp.zig:12:5: error: switch on non-exhaustive enum must include `else` or `_` prong",
"tmp.zig:12:5: error: enumeration value 'E.b' not handled in switch",
"tmp.zig:16:5: error: switch on non-exhaustive enum must include `else` or `_` prong",
"tmp.zig:21:5: error: `_` prong not allowed when switching on tagged union",
});
cases.add("switch expression - unreachable else prong (bool)",