Parser: do not define typedefs with invalid types

[ehaas]

Putting invalid typedefs into the symbol table is problematic because if they get redefined, we try to render the original type (not possible for invalid types) for the error message.

Closes #645

[ehaas]

Looks like the zig compiler is crashing; happens on master for me as well:

* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x7feaf030a217)
  * frame #0: 0x0000000107873d4a zig`InternPool.indexToKey + 58
    frame #1: 0x00000001079abcc9 zig`type.Type.comptimeOnlyAdvanced + 89
    frame #2: 0x00000001079ac1ea zig`type.Type.comptimeOnlyAdvanced + 1402
    frame #3: 0x00000001079abd2f zig`type.Type.comptimeOnlyAdvanced + 191
    frame #4: 0x00000001079b20e4 zig`Sema.resolveStructAlignment + 292
    frame #5: 0x00000001078ca0ba zig`type.Type.abiAlignmentAdvanced + 3402
    frame #6: 0x00000001078c8fd1 zig`Value.getUnsignedIntAdvanced + 913
    frame #7: 0x0000000107cb26c6 zig`Sema.zirPtrType + 1846
    frame #8: 0x0000000107ab98b4 zig`Sema.analyzeBodyInner + 27220
    frame #9: 0x00000001079a975e zig`Sema.analyzeInlineBody + 30
    frame #10: 0x0000000107b3792b zig`Sema.resolveTypeFieldsStruct + 3643
    frame #11: 0x00000001079ac103 zig`type.Type.comptimeOnlyAdvanced + 1171
    frame #12: 0x00000001079abd2f zig`type.Type.comptimeOnlyAdvanced + 191
    frame #13: 0x0000000107ce0c27 zig`Sema.zirParam + 871
    frame #14: 0x0000000107acf610 zig`Sema.analyzeBodyInner + 116656
    frame #15: 0x00000001078ce608 zig`Module.semaDecl + 2904
    frame #16: 0x00000001077c8563 zig`Module.ensureDeclAnalyzed + 14195
    frame #17: 0x0000000107d223d2 zig`Sema.ensureDeclAnalyzed + 258
    frame #18: 0x0000000107d25d8d zig`Sema.analyzeDeclRefInner + 45
    frame #19: 0x0000000107ab602d zig`Sema.analyzeBodyInner + 12749
    frame #20: 0x0000000107ad0c4a zig`Sema.analyzeBodyInner + 122346
    frame #21: 0x0000000107ab32c5 zig`Sema.analyzeBodyInner + 1125
    frame #22: 0x00000001078ce608 zig`Module.semaDecl + 2904
    frame #23: 0x00000001077c8563 zig`Module.ensureDeclAnalyzed + 14195
    frame #24: 0x00000001078a6724 zig`Compilation.processOneJob + 2996
    frame #25: 0x00000001077e43f4 zig`Compilation.update + 15908
    frame #26: 0x00000001077f91c1 zig`main.updateModule + 417
    frame #27: 0x000000010783b41e zig`main.buildOutputType + 70830
    frame #28: 0x0000000107745fa5 zig`main.main + 6885
    frame #29: 0x0000000107744466 zig`main + 102

[Vexu]

Putting invalid typedefs into the symbol table is problematic because if they get redefined, we try to render the original type (not possible for invalid types) for the error message.

Wouldn't it be better to allow redefinitions if the previous type is invalid? Since there was already a hit it should be in the slow path as well.

Also I'm going to look into the crash now.

[Vexu]

Master branch is green so this should be unblocked.

[ehaas]

@Vexu I forced pushed - is this what you had in mind by allowing redefinitions of invalid types? I believe they were always allowed; it's just that we issue an error diagnostic. So now I skip the diagnostic if the previous typedef was an invalid type.

[Vexu]

is this what you had in mind by allowing redefinitions of invalid types? I believe they were always allowed; it's just that we issue an error diagnostic. So now I skip the diagnostic if the previous typedef was an invalid type.

It is.