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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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70
compiler/rustc_expand/src/proc_macro_server.rs
View file

@ -2,16 +2,21 @@ use crate::base::ExtCtxt;
use rustc_ast as ast;
use rustc_ast::token;
use rustc_ast::token::Nonterminal;
use rustc_ast::token::NtIdent;
use rustc_ast::tokenstream::{self, CanSynthesizeMissingTokens};
use rustc_ast::tokenstream::{DelimSpan, Spacing::*, TokenStream, TreeAndSpacing};
use rustc_ast_pretty::pprust;
use rustc_data_structures::sync::Lrc;
use rustc_errors::Diagnostic;
use rustc_lint_defs::builtin::PROC_MACRO_BACK_COMPAT;
use rustc_lint_defs::BuiltinLintDiagnostics;
use rustc_parse::lexer::nfc_normalize;
use rustc_parse::{nt_to_tokenstream, parse_stream_from_source_str};
use rustc_session::parse::ParseSess;
use rustc_span::hygiene::ExpnKind;
use rustc_span::symbol::{self, kw, sym, Symbol};
use rustc_span::{BytePos, FileName, MultiSpan, Pos, SourceFile, Span};
use rustc_span::{BytePos, FileName, MultiSpan, Pos, RealFileName, SourceFile, Span};
use pm::bridge::{server, TokenTree};
use pm::{Delimiter, Level, LineColumn, Spacing};
@ -174,9 +179,7 @@ impl FromInternal<(TreeAndSpacing, &'_ ParseSess, &'_ mut Vec<Self>)>
}
Interpolated(nt) => {
if let Some((name, is_raw)) =
nt.ident_name_compatibility_hack(span, sess.source_map())
{
if let Some((name, is_raw)) = ident_name_compatibility_hack(&nt, span, sess) {
TokenTree::Ident(Ident::new(sess, name.name, is_raw, name.span))
} else {
let stream = nt_to_tokenstream(&nt, sess, CanSynthesizeMissingTokens::No);
@ -711,3 +714,62 @@ impl server::Span for Rustc<'_> {
self.sess.source_map().span_to_snippet(span).ok()
}
}
// See issue #74616 for details
fn ident_name_compatibility_hack(
nt: &Nonterminal,
orig_span: Span,
sess: &ParseSess,
) -> Option<(rustc_span::symbol::Ident, bool)> {
if let NtIdent(ident, is_raw) = nt {
if let ExpnKind::Macro(_, macro_name) = orig_span.ctxt().outer_expn_data().kind {
let source_map = sess.source_map();
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))
};
let time_macros_impl =
macro_name == sym::impl_macros && matches_prefix("time-macros-impl", "lib.rs");
if time_macros_impl
|| (macro_name == sym::arrays && matches_prefix("js-sys", "lib.rs"))
{
let snippet = source_map.span_to_snippet(orig_span);
if snippet.as_deref() == Ok("$name") {
if time_macros_impl {
sess.buffer_lint_with_diagnostic(
&PROC_MACRO_BACK_COMPAT,
orig_span,
ast::CRATE_NODE_ID,
"using an old version of `time-macros-impl`",
BuiltinLintDiagnostics::ProcMacroBackCompat(
"the `time-macros-impl` crate will stop compiling in futures version of Rust. \
Please update to the latest version of the `time` crate to avoid breakage".to_string())
);
}
return Some((*ident, *is_raw));
}
}
if macro_name == sym::tuple_from_req
&& (matches_prefix("actix-web", "extract.rs")
|| matches_prefix("actori-web", "extract.rs"))
{
let snippet = source_map.span_to_snippet(orig_span);
if snippet.as_deref() == Ok("$T") {
return Some((*ident, *is_raw));
}
}
}
}
}
None
}