regression processing c-style doc comments in proc macros between 1.46 and 1.47 #80545
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Description
When a proc macro is applied to an item that has an associated c-style doc comment the contents of the TokenStream changed between 1.46 and 1.47. In particular the surrounding * and newlines were previously elided (mostly), but as of 1.47 they are not.
Code
Here's a little repo I put together to demonstrate and reproduce the issue: https://github.com/ahl/cdoc_regression. It contains a proc macro that looks like this:
#[proc_macro_attribute]
pub fn return_as_is(_attr: TokenStream, item: TokenStream) -> TokenStream {
for token in item.clone() {
match token {
TokenTree::Group(group) if group.delimiter() == Delimiter::Bracket => {
println!("{:}", group)
}
_ => {}
}
}
item
}Here's the output:
$ cargo +1.46.0 run --example test
Compiling fun v0.1.0 (/Users/ahl/src/cdoc_regression)
[doc = " This is a multi-"]
[doc = " line comment."]
[doc = " This is another multi-\n line comment."]
Finished dev [unoptimized + debuginfo] target(s) in 0.30s
Running `target/debug/examples/test`
$ cargo +1.47.0 run --example test
Compiling fun v0.1.0 (/Users/ahl/src/cdoc_regression)
[doc = " This is a multi-"]
[doc = " line comment."]
[doc = "\n * This is another multi-\n * line comment.\n "]
Finished dev [unoptimized + debuginfo] target(s) in 0.27s
Running `target/debug/examples/test`
In both cases, the first multiline comment is for a ///-style comment and the second is for a /**-style comment.
Version it worked on
rustc 1.46.0 (04488afe3 2020-08-24)
binary: rustc
commit-hash: 04488afe34512aa4c33566eb16d8c912a3ae04f9
commit-date: 2020-08-24
host: x86_64-apple-darwin
release: 1.46.0
LLVM version: 10.0
Version with regression
rustc 1.47.0 (18bf6b4f0 2020-10-07)
binary: rustc
commit-hash: 18bf6b4f01a6feaf7259ba7cdae58031af1b7b39
commit-date: 2020-10-07
host: x86_64-apple-darwin
release: 1.47.0
LLVM version: 11.0
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Area: The parsing of Rust source code to an ASTArea: Procedural macrosCall for participation: This issue needs bisection: https://github.com/rust-lang/cargo-bisect-rustcMedium priorityRelevant to the compiler team, which will review and decide on the PR/issue.Performance or correctness regression from one stable version to another.