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Introduce proc_macro_back_compat lint, and emit for time-macros-impl

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Now that future-incompat-report support has landed in nightly Cargo, we
can start to make progress towards removing the various proc-macro
back-compat hacks that have accumulated in the compiler.

This PR introduces a new lint `proc_macro_back_compat`, which results in
a future-incompat-report entry being generated. All proc-macro
back-compat warnings will be grouped under this lint. Note that this
lint will never actually become a hard error - instead, we will remove
the special cases for various macros, which will cause older versions of
those crates to emit some other error.

I've added code to fire this lint for the `time-macros-impl` case. This
is the easiest case out of all of our current back-compat hacks - the
crate was renamed to `time-macros`, so seeing a filename with
`time-macros-impl` guarantees that an older version of the parent `time`
crate is in use.

When Cargo's future-incompat-report feature gets stabilized, affected
users will start to see future-incompat warnings when they build their
crates.
This commit is contained in:
Aaron Hill 2021-03-14 16:55:59 -04:00
parent d6eaea1c88
commit f190bc4f47
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GPG key ID: B4087E510E98B164
8 changed files with 206 additions and 65 deletions
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50
compiler/rustc_ast/src/token.rs
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@ -11,11 +11,9 @@ use crate::tokenstream::TokenTree;
use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
use rustc_data_structures::sync::Lrc;
use rustc_macros::HashStable_Generic;
use rustc_span::hygiene::ExpnKind;
use rustc_span::source_map::SourceMap;
use rustc_span::symbol::{kw, sym};
use rustc_span::symbol::{Ident, Symbol};
use rustc_span::{self, edition::Edition, FileName, RealFileName, Span, DUMMY_SP};
use rustc_span::{self, edition::Edition, Span, DUMMY_SP};
use std::borrow::Cow;
use std::{fmt, mem};
@ -813,52 +811,6 @@ impl Nonterminal {
}
false
}
// See issue #74616 for details
pub fn ident_name_compatibility_hack(
&self,
orig_span: Span,
source_map: &SourceMap,
) -> Option<(Ident, bool)> {
if let NtIdent(ident, is_raw) = self {
if let ExpnKind::Macro(_, macro_name) = orig_span.ctxt().outer_expn_data().kind {
let filename = source_map.span_to_filename(orig_span);
if let FileName::Real(RealFileName::Named(path)) = filename {
let matches_prefix = |prefix, filename| {
// Check for a path that ends with 'prefix*/src/<filename>'
let mut iter = path.components().rev();
iter.next().and_then(|p| p.as_os_str().to_str()) == Some(filename)
&& iter.next().and_then(|p| p.as_os_str().to_str()) == Some("src")
&& iter
.next()
.and_then(|p| p.as_os_str().to_str())
.map_or(false, |p| p.starts_with(prefix))
};
if (macro_name == sym::impl_macros
&& matches_prefix("time-macros-impl", "lib.rs"))
|| (macro_name == sym::arrays && matches_prefix("js-sys", "lib.rs"))
{
let snippet = source_map.span_to_snippet(orig_span);
if snippet.as_deref() == Ok("$name") {
return Some((*ident, *is_raw));
}
}
if macro_name == sym::tuple_from_req
&& (matches_prefix("actix-web", "extract.rs")
|| matches_prefix("actori-web", "extract.rs"))
{
let snippet = source_map.span_to_snippet(orig_span);
if snippet.as_deref() == Ok("$T") {
return Some((*ident, *is_raw));
}
}
}
}
}
None
}
}
impl PartialEq for Nonterminal {