Disallow compile time bindings where they aren't clearly supported. #4338
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Note, if you prefer, I think I could also only disallow in class and impl scopes. Those both should have suspended function issues. Package scope I think I can actually make work under the current approach. |
zygoloid
approved these changes
Sep 25, 2024
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| let a:! () = (); | ||
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| // --- implicit.impl.carbon | ||
| // --- fail_implicit.impl.carbon | ||
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| impl package Implicit; | ||
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| // CHECK:STDERR: fail_implicit.impl.carbon:[[@LINE+4]]:5: error: `let` compile time bindings require function or interface (may be supported later) | ||
| // CHECK:STDERR: let b:! () = a; | ||
| // CHECK:STDERR: ^~~~~~ | ||
| // CHECK:STDERR: | ||
| let b:! () = a; | ||
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| // --- other.carbon | ||
| // --- fail_other.carbon | ||
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| package Other; | ||
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| // CHECK:STDERR: fail_other.carbon:[[@LINE+4]]:5: error: `let` compile time bindings require function or interface (may be supported later) | ||
| // CHECK:STDERR: let a:! () = (); | ||
| // CHECK:STDERR: ^~~~~~ | ||
| // CHECK:STDERR: | ||
| let a:! () = (); | ||
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| // --- import_other.carbon | ||
| // --- fail_import_other.carbon | ||
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| import Other; | ||
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| // CHECK:STDERR: fail_import_other.carbon:[[@LINE+3]]:5: error: `let` compile time bindings require function or interface (may be supported later) | ||
| // CHECK:STDERR: let b:! () = Other.a; | ||
| // CHECK:STDERR: ^~~~~~ | ||
| let b:! () = Other.a; |
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Can we change these from :! to : bindings? It doesn't look like this test was trying to test compile time bindings in particular.
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
geoffromer
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to geoffromer/carbon-lang
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Oct 7, 2024
We now allow `let` bindings in all scopes except `class` and `impl`, which are known to be problematic. This also switches to GetCurrentScopeAs instead of PeekInstId, to better encapsulate handling of invalid scope inst IDs. This fixes a fuzzer-found crash when a compile-time binding occurs inside a block (which is represented by an invalid inst ID). This partially reverts carbon-language#4338, but is consistent with @jonmeow's comments on that PR.
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This is resolving a fuzz-discovered crash related to function suspends and compile time bind indices. Although the crash originally came from clearly invalid syntax (missing the
=inside aclassdecl), the syntax with a value should also be valid but has the same crash.This approach disallows compile-time bindings in contexts that can create ambiguous results, particularly class declarations. These are an issue because a suspended function can have let declarations after it. I'm allowing them in function bodies and interface scopes.