Typecheck else expression of let-else to ensure it diverges#3469
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CohenArthur wants to merge 2 commits intoRust-GCC:masterfrom
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Typecheck else expression of let-else to ensure it diverges#3469CohenArthur wants to merge 2 commits intoRust-GCC:masterfrom
else expression of let-else to ensure it diverges#3469CohenArthur wants to merge 2 commits intoRust-GCC:masterfrom
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CohenArthur
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| // FIXME: Is that enough? Do we need to do something like | ||
| // `append_reference` here as well? |
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@philberty I'm not sure if there's anything else we need to do here. I was trying to use something like coercion_site(...) but obviously it doesn't work because any type is coercible to !, which is not the behavior we actually want here
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! should be coercible to any other type, but not the other way around
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Ah ok yeah this is enough because all you need to do is check for ! in the else case so yes this is correct! Dont need to do unify or coercion site because it doesnt need to do anything else.
Dont think we support this in codegen
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gcc/rust/ChangeLog: * resolve/rust-late-name-resolver-2.0.cc (Late::visit): Visit the `else` expression instead of the `init` one if the let is a let-else.
Make sure the `else` expression resolves to the never type. gcc/rust/ChangeLog: * typecheck/rust-hir-type-check-stmt.cc (TypeCheckStmt::visit): Check diverging else against `!`. gcc/testsuite/ChangeLog: * rust/compile/let-else-invalid-type.rs: New test.
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The
elseexpression of alet-elsemust always diverge, which we enforce during typecheck. Needs #3468