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Inconsistent rustdoc constant expansion from macro #115295
Description
I tried this code:
pub struct WithConst<const N: usize>;
pub trait Trait<T> {}
macro_rules! spans_from_macro {
() => {
impl Trait<WithConst<42>> for WithConst<42> {}
impl WithConst<42> {
pub fn new() -> Self {
Self
}
}
pub struct Other {
pub field: WithConst<42>,
}
};
}
// doc: impl Trait<WithConst<41>> for WithConst<41>
impl Trait<WithConst<41>> for WithConst<41> {}
// doc: impl Trait<WithConst<42>> for WithConst<{ _ }>
// impl WithConst<{ _ }>
// struct Other { pub field: WithConst<{ _ }> }
spans_from_macro!();I expected to see this happen: constants are formatted as either all { _ }, or all 42.
Instead, this happened: the one in the trait generic is formatted as the literal 42, while everywhere else it's formatted as { _ }.
I assume it's this:
rust/src/librustdoc/clean/utils.rs
Lines 436 to 438 in 8550f15
which can be expanded on to also format the literal if it's coming from a macro span by using the pretty printer.
Meta
rustc --version --verbose:
rustc 1.74.0-nightly (5c6a7e71c 2023-08-20)
binary: rustc
commit-hash: 5c6a7e71cd66705c31c9af94077901a220f0870c
commit-date: 2023-08-20
host: x86_64-unknown-linux-gnu
release: 1.74.0-nightly
LLVM version: 17.0.0
Backtrace
N/A
@rustbot label A-rustdoc-ui T-rustdoc
Activity
Rollup merge of rust-lang#115485 - DaniPopes:rustdoc-macro-consts, r=…
Unrolled build for rust-lang#115485