fix: try to infer array type from slice pattern #19066
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rust-analyzer equivalent of rust-lang/rust#2827aa97
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| /// Determines whether we can infer the expected type in the slice pattern to be of type array. | ||
| /// This is only possible if we're in an irrefutable pattern. If we were to allow this in refutable | ||
| /// patterns we wouldn't e.g. report ambiguity in the following situation: |
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The compiler doesn't report ambiguity (https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=574bb654d0bd9905773ec8a82246c446), are you sure this logic is correct?
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That's copied from the corresponding rustc PR, though not sure why the text wasnt just copied verbatim https://github.com/rust-lang/rust/pull/113199/files#diff-9f26e4ec8d6ac64edbb3532a590592556b268b0e33f9fd4264d5d449aebbecf7R2061-R2090
crates/hir-ty/src/infer/pat.rs
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| if let Some(decl_ctxt) = decl_ctxt { | ||
| !decl_ctxt.has_else && matches!(decl_ctxt.origin, DeclOrigin::LocalDecl) | ||
| } else { | ||
| false | ||
| } |
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| if let Some(decl_ctxt) = decl_ctxt { | |
| !decl_ctxt.has_else && matches!(decl_ctxt.origin, DeclOrigin::LocalDecl) | |
| } else { | |
| false | |
| } | |
| matches!(decl_ctxt, Some(DeclContext { origin: DeclOrigin::LocalDecl, has_else: true}) |
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| /// Determines whether we can infer the expected type in the slice pattern to be of type array. | ||
| /// This is only possible if we're in an irrefutable pattern. If we were to allow this in refutable | ||
| /// patterns we wouldn't e.g. report ambiguity in the following situation: |
There was a problem hiding this comment.
That's copied from the corresponding rustc PR, though not sure why the text wasnt just copied verbatim https://github.com/rust-lang/rust/pull/113199/files#diff-9f26e4ec8d6ac64edbb3532a590592556b268b0e33f9fd4264d5d449aebbecf7R2061-R2090
crates/hir-ty/src/infer/expr.rs
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| @@ -334,7 +334,7 @@ impl InferenceContext<'_> { | |||
| ExprIsRead::No | |||
| }; | |||
| let input_ty = self.infer_expr(expr, &Expectation::none(), child_is_read); | |||
| self.infer_top_pat(pat, &input_ty); | |||
| self.infer_top_pat(pat, &input_ty, None); | |||
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While we have no use for it now, we should put a Some(DeclContext { origin: DeclOrigin::LetExpr } here
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Looks good to me now 👍 |
And apply requested changes
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fixes #16609