proc_macro: Stop flattening groups with dummy spans #73102
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@bors try |
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⌛ Trying commit d754b6fccd23147e425772d925152c7ef19850be with merge 71b81291baafb8a58836272757b28817fe1d8190... |
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☀️ Try build successful - checks-azure |
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Interesting and surprising. |
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Closing in favor of #73345 which is simpler and more principled. |
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Rebased and added some comments. |
Aaron1011
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Jun 25, 2020
Aaron1011
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Jun 25, 2020
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r=me with the nits fixed |
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@bors r=Aaron1011 |
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📌 Commit 77b0ed7 has been approved by |
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Manishearth
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Jun 26, 2020
proc_macro: Stop flattening groups with dummy spans Reduce the scope of the hack described in rust-lang#72545 (comment). We still pass AST fragments to attribute and derive macros as single nonterminal tokens rather than as tokens streams, but now use a precise flag instead of the span-based heuristic that could do lead to incorrect behavior in unrelated cases. rust-lang#73345 attempts to fully resolve this issue, but there are some compatibility issues to be addressed.
This was referenced Jun 26, 2020
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Jun 26, 2020
…arth Rollup of 13 pull requests Successful merges: - rust-lang#72620 (Omit DW_AT_linkage_name when it is the same as DW_AT_name) - rust-lang#72967 (Don't move cursor in search box when using arrows to navigate results) - rust-lang#73102 (proc_macro: Stop flattening groups with dummy spans) - rust-lang#73297 (Support configurable deny-warnings for all in-tree crates.) - rust-lang#73507 (Cleanup MinGW LLVM linkage workaround) - rust-lang#73588 (Fix handling of reserved registers for ARM inline asm) - rust-lang#73597 (Record span of `const` kw in GenericParamKind) - rust-lang#73629 (Make AssocOp Copy) - rust-lang#73681 (Update Chalk to 0.14) - rust-lang#73707 (Fix links in `SliceIndex` documentation) - rust-lang#73719 (emitter: column width defaults to 140) - rust-lang#73729 (disable collectionbenches for android) - rust-lang#73748 (Add code block to code in documentation of `List::rebase_onto`) Failed merges: r? @ghost
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I suspect this may have caused a perf regression. I'm going to try to do a perf CI run after the landing. Not sure if it will work... @bors try @rust-timer queue |
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Awaiting bors try build completion |
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Bors doesn't listen on closed issues/PRs. |
Manishearth
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expand: Stop using nonterminals for passing tokens to attribute and derive macros Make one more step towards fully token-based expansion and fix issues described in rust-lang#72545 (comment). Now `struct S;` is passed to `foo!(struct S;)` and `#[foo] struct S;` in the same way - as a token stream `struct S ;`, rather than a single non-terminal token `NtItem` which is then broken into parts later. The cost is making pretty-printing of token streams less pretty. Some of the pretty-printing regressions will be recovered by keeping jointness with each token, which we will need to do anyway. Unfortunately, this is not exactly the same thing as rust-lang#73102. One more observable effect is how `$crate` is printed in the attribute input. Inside `NtItem` was printed as `crate` or `that_crate`, now as a part of a token stream it's printed as `$crate` (there are good reasons for these differences, see rust-lang#62393 and related PRs). This may break old proc macros (custom derives) written before the main portion of the proc macro API (macros 1.2) was stabilized, those macros did `input.to_string()` and reparsed the result, now that result can contain `$crate` which cannot be reparsed. So, I think we should do this regardless, but we need to run crater first. r? @Aaron1011
Manishearth
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Jul 2, 2020
expand: Stop using nonterminals for passing tokens to attribute and derive macros Make one more step towards fully token-based expansion and fix issues described in rust-lang#72545 (comment). Now `struct S;` is passed to `foo!(struct S;)` and `#[foo] struct S;` in the same way - as a token stream `struct S ;`, rather than a single non-terminal token `NtItem` which is then broken into parts later. The cost is making pretty-printing of token streams less pretty. Some of the pretty-printing regressions will be recovered by keeping jointness with each token, which we will need to do anyway. Unfortunately, this is not exactly the same thing as rust-lang#73102. One more observable effect is how `$crate` is printed in the attribute input. Inside `NtItem` was printed as `crate` or `that_crate`, now as a part of a token stream it's printed as `$crate` (there are good reasons for these differences, see rust-lang#62393 and related PRs). This may break old proc macros (custom derives) written before the main portion of the proc macro API (macros 1.2) was stabilized, those macros did `input.to_string()` and reparsed the result, now that result can contain `$crate` which cannot be reparsed. So, I think we should do this regardless, but we need to run crater first. r? @Aaron1011
Manishearth
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Jul 2, 2020
expand: Stop using nonterminals for passing tokens to attribute and derive macros Make one more step towards fully token-based expansion and fix issues described in rust-lang#72545 (comment). Now `struct S;` is passed to `foo!(struct S;)` and `#[foo] struct S;` in the same way - as a token stream `struct S ;`, rather than a single non-terminal token `NtItem` which is then broken into parts later. The cost is making pretty-printing of token streams less pretty. Some of the pretty-printing regressions will be recovered by keeping jointness with each token, which we will need to do anyway. Unfortunately, this is not exactly the same thing as rust-lang#73102. One more observable effect is how `$crate` is printed in the attribute input. Inside `NtItem` was printed as `crate` or `that_crate`, now as a part of a token stream it's printed as `$crate` (there are good reasons for these differences, see rust-lang#62393 and related PRs). This may break old proc macros (custom derives) written before the main portion of the proc macro API (macros 1.2) was stabilized, those macros did `input.to_string()` and reparsed the result, now that result can contain `$crate` which cannot be reparsed. So, I think we should do this regardless, but we need to run crater first. r? @Aaron1011
Manishearth
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Jul 2, 2020
expand: Stop using nonterminals for passing tokens to attribute and derive macros Make one more step towards fully token-based expansion and fix issues described in rust-lang#72545 (comment). Now `struct S;` is passed to `foo!(struct S;)` and `#[foo] struct S;` in the same way - as a token stream `struct S ;`, rather than a single non-terminal token `NtItem` which is then broken into parts later. The cost is making pretty-printing of token streams less pretty. Some of the pretty-printing regressions will be recovered by keeping jointness with each token, which we will need to do anyway. Unfortunately, this is not exactly the same thing as rust-lang#73102. One more observable effect is how `$crate` is printed in the attribute input. Inside `NtItem` was printed as `crate` or `that_crate`, now as a part of a token stream it's printed as `$crate` (there are good reasons for these differences, see rust-lang#62393 and related PRs). This may break old proc macros (custom derives) written before the main portion of the proc macro API (macros 1.2) was stabilized, those macros did `input.to_string()` and reparsed the result, now that result can contain `$crate` which cannot be reparsed. So, I think we should do this regardless, but we need to run crater first. r? @Aaron1011
Manishearth
added a commit
to Manishearth/rust
that referenced
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Jul 2, 2020
expand: Stop using nonterminals for passing tokens to attribute and derive macros Make one more step towards fully token-based expansion and fix issues described in rust-lang#72545 (comment). Now `struct S;` is passed to `foo!(struct S;)` and `#[foo] struct S;` in the same way - as a token stream `struct S ;`, rather than a single non-terminal token `NtItem` which is then broken into parts later. The cost is making pretty-printing of token streams less pretty. Some of the pretty-printing regressions will be recovered by keeping jointness with each token, which we will need to do anyway. Unfortunately, this is not exactly the same thing as rust-lang#73102. One more observable effect is how `$crate` is printed in the attribute input. Inside `NtItem` was printed as `crate` or `that_crate`, now as a part of a token stream it's printed as `$crate` (there are good reasons for these differences, see rust-lang#62393 and related PRs). This may break old proc macros (custom derives) written before the main portion of the proc macro API (macros 1.2) was stabilized, those macros did `input.to_string()` and reparsed the result, now that result can contain `$crate` which cannot be reparsed. So, I think we should do this regardless, but we need to run crater first. r? @Aaron1011
flip1995
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Jul 14, 2020
…arth Rollup of 13 pull requests Successful merges: - rust-lang#72620 (Omit DW_AT_linkage_name when it is the same as DW_AT_name) - rust-lang#72967 (Don't move cursor in search box when using arrows to navigate results) - rust-lang#73102 (proc_macro: Stop flattening groups with dummy spans) - rust-lang#73297 (Support configurable deny-warnings for all in-tree crates.) - rust-lang#73507 (Cleanup MinGW LLVM linkage workaround) - rust-lang#73588 (Fix handling of reserved registers for ARM inline asm) - rust-lang#73597 (Record span of `const` kw in GenericParamKind) - rust-lang#73629 (Make AssocOp Copy) - rust-lang#73681 (Update Chalk to 0.14) - rust-lang#73707 (Fix links in `SliceIndex` documentation) - rust-lang#73719 (emitter: column width defaults to 140) - rust-lang#73729 (disable collectionbenches for android) - rust-lang#73748 (Add code block to code in documentation of `List::rebase_onto`) Failed merges: r? @ghost
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Reduce the scope of the hack described in #72545 (comment).
We still pass AST fragments to attribute and derive macros as single nonterminal tokens rather than as tokens streams, but now use a precise flag instead of the span-based heuristic that could do lead to incorrect behavior in unrelated cases.
#73345 attempts to fully resolve this issue, but there are some compatibility issues to be addressed.