592d113ff2
This makes the expression re-parsing more like how it's originally done in `parse_nonterminal`.
133 lines
2.7 KiB
Rust
133 lines
2.7 KiB
Rust
//@ check-pass
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//
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// During development of #124141 at one point expression on attributes were
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// being duplicated and `m1` caused an exponential blowup that caused OOM.
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// The number of recursive calls depends on the number of doc comments on the
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// expr block. On each recursive call, the `#[allow(deprecated)]` attribute(s) on
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// the `0` somehow get duplicated, resulting in 1, 2, 4, 8, ... identical
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// attributes.
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//
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// After the fix, the code compiles quickly and normally.
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macro_rules! m1 {
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($(#[$meta:meta])* { $e:expr }) => {
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m1! { expr: { $e }, unprocessed: [$(#[$meta])*] }
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};
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(expr: { $e:expr }, unprocessed: [ #[$meta:meta] $($metas:tt)* ]) => {
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m1! { expr: { $e }, unprocessed: [ $($metas)* ] }
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};
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(expr: { $e:expr }, unprocessed: []) => {
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{ $e }
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}
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}
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macro_rules! m2 {
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($(#[$meta:meta])* { $e:stmt }) => {
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m2! { stmt: { $e }, unprocessed: [$(#[$meta])*] }
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};
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(stmt: { $e:stmt }, unprocessed: [ #[$meta:meta] $($metas:tt)* ]) => {
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m2! { stmt: { $e }, unprocessed: [ $($metas)* ] }
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};
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(stmt: { $e:stmt }, unprocessed: []) => {
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{ $e }
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}
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}
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macro_rules! m3 {
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($(#[$meta:meta])* { $e:item }) => {
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m3! { item: { $e }, unprocessed: [$(#[$meta])*] }
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};
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(item: { $e:item }, unprocessed: [ #[$meta:meta] $($metas:tt)* ]) => {
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m3! { item: { $e }, unprocessed: [ $($metas)* ] }
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};
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(item: { $e:item }, unprocessed: []) => {
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{ $e }
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}
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}
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fn main() {
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// Each additional doc comment line doubles the compile time.
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m1!(
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/// a1
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/// a2
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/// a3
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/// a4
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/// a5
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/// a6
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/// a7
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/// a8
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/// a9
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/// a10
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/// a11
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/// a12
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/// a13
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/// a14
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/// a15
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/// a16
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/// a17
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/// a18
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/// a19
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/// a20
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{
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#[allow(deprecated)] 0
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}
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);
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m2!(
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/// a1
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/// a2
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/// a3
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/// a4
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/// a5
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/// a6
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/// a7
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/// a8
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/// a9
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/// a10
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/// a11
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/// a12
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/// a13
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/// a14
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/// a15
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/// a16
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/// a17
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/// a18
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/// a19
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/// a20
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{
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#[allow(deprecated)] let x = 5
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}
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);
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m3!(
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/// a1
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/// a2
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/// a3
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/// a4
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/// a5
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/// a6
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/// a7
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/// a8
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/// a9
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/// a10
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/// a11
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/// a12
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/// a13
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/// a14
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/// a15
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/// a16
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/// a17
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/// a18
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/// a19
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/// a20
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{
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#[allow(deprecated)] struct S;
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}
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);
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}
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