resolve: Disambiguate a subset of conflicts "macro_rules" vs "macro name in module" #54605
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cc @rust-lang/lang |
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This all looks and sounds good to me, thanks @petrochenkov! r=me with some tests |
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📌 Commit d8887bf61a626f39e26302902128b6915517c99a has been approved by |
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Argh, asserts are firing. Will fix tomorrow. |
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📌 Commit 078fc52 has been approved by |
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resolve: Disambiguate a subset of conflicts "macro_rules" vs "macro name in module" Currently if macro name may refer to both a `macro_rules` macro definition and a macro defined/imported into module we conservatively report an ambiguity error. Unfortunately, these errors became a source of regressions when macro modularization was enabled - see issue #54472. This PR disambiguates such conflicts in favor of `macro_rules` if both the `macro_rules` item and in-module macro name are defined in the same normal (named) module and `macro_rules` is closer in scope to the point of use (see the tests for examples). This is a subset of more general approach described in #54472 (comment). The subset is enough to fix all the regressions from #54472, but it can be extended to apply to all "macro_rules" vs "macro name in module" conflicts in the future. To give an analogy, this is equivalent to scoping rules for `let` variables and items defined in blocks (`macro_rules` behaves like "`let` at module level" in general). ```rust { // beginning of the block use xxx::m; // (1) // Starting from the beginning of the block and until here m!() refers to (1) macro_rules! m { ... } // (2) // Starting from here and until the end of the block m!() refers to (2) } // end of the block ``` More complex examples with `use` and `macro_rules` from different modules still report ambiguity errors, even if equivalent examples with `let` are legal. Fixes #54472 (stable-to-beta regression)
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💔 Test failed - status-travis |
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The relevant link error message: |
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Spurious? I don't this emscripten-specific linking error has anything to do with my PR. |
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resolve: Disambiguate a subset of conflicts "macro_rules" vs "macro name in module" Currently if macro name may refer to both a `macro_rules` macro definition and a macro defined/imported into module we conservatively report an ambiguity error. Unfortunately, these errors became a source of regressions when macro modularization was enabled - see issue #54472. This PR disambiguates such conflicts in favor of `macro_rules` if both the `macro_rules` item and in-module macro name are defined in the same normal (named) module and `macro_rules` is closer in scope to the point of use (see the tests for examples). This is a subset of more general approach described in #54472 (comment). The subset is enough to fix all the regressions from #54472, but it can be extended to apply to all "macro_rules" vs "macro name in module" conflicts in the future. To give an analogy, this is equivalent to scoping rules for `let` variables and items defined in blocks (`macro_rules` behaves like "`let` at module level" in general). ```rust { // beginning of the block use xxx::m; // (1) // Starting from the beginning of the block and until here m!() refers to (1) macro_rules! m { ... } // (2) // Starting from here and until the end of the block m!() refers to (2) } // end of the block ``` More complex examples with `use` and `macro_rules` from different modules still report ambiguity errors, even if equivalent examples with `let` are legal. Fixes #54472 (stable-to-beta regression)
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☀️ Test successful - status-appveyor, status-travis |
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discussed at T-compiler meeting. accepting for beta backport. |
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[beta] Rollup backports Merged and approved: * #54605: resolve: Disambiguate a subset of conflicts "macro_rules" vs "macro name in module" * #54557: incr.comp.: Don't automatically enable -Zshare-generics for incr. comp. builds. * #54759: do not normalize non-scalar constants to a ConstValue::ScalarPair Closes #54759 r? @ghost
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Currently if macro name may refer to both a
macro_rulesmacro definition and a macro defined/imported into module we conservatively report an ambiguity error.Unfortunately, these errors became a source of regressions when macro modularization was enabled - see issue #54472.
This PR disambiguates such conflicts in favor of
macro_rulesif both themacro_rulesitem and in-module macro name are defined in the same normal (named) module andmacro_rulesis closer in scope to the point of use (see the tests for examples).This is a subset of more general approach described in #54472 (comment).
The subset is enough to fix all the regressions from #54472, but it can be extended to apply to all "macro_rules" vs "macro name in module" conflicts in the future.
To give an analogy, this is equivalent to scoping rules for
letvariables and items defined in blocks (macro_rulesbehaves like "letat module level" in general).More complex examples with
useandmacro_rulesfrom different modules still report ambiguity errors, even if equivalent examples withletare legal.Fixes #54472 (stable-to-beta regression)