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Extend proc_macro_back_compat lint to procedural-masquerade

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We now lint on *any* use of `procedural-masquerade` crate. While this
crate still exists, its main reverse dependency (`cssparser`) no longer
depends on it. Any crates still depending off should stop doing so, as
it only exists to support very old Rust versions.

If a crate actually needs to support old versions of rustc via
`procedural-masquerade`, then they'll just need to accept the warning
until we remove it entirely (at the same time as the back-compat hack).
The latest version of `procedural-masquerade` does not work with the
latest rustc, but trying to check for the version seems like more
trouble than it's worth.

While working on this, I realized that the `proc-macro-hack` check was
never actually doing anything. The corresponding enum variant in
`proc-macro-hack` is named `Value` or `Nested` - it has never been
called `Input`. Due to a strange Crater issue, the Crater run that
tested adding this did *not* end up testing it - some of the crates that
would have failed did not actually have their tests checked, making it
seem as though the `proc-macro-hack` check was working.

The Crater issue is being discussed at
https://rust-lang.zulipchat.com/#narrow/stream/242791-t-infra/topic/Nearly.20identical.20Crater.20runs.20processed.20a.20crate.20differently/near/230406661

Despite the `proc-macro-hack` check not actually doing anything, we
haven't gotten any reports from users about their build being broken.
I went ahead and removed it entirely, since it's clear that no one is
being affected by the `proc-macro-hack` regression in practice.
This commit is contained in:
Aaron Hill 2021-03-15 15:54:25 -04:00
parent 2ccf06302c
commit d6a7c1d47f
No known key found for this signature in database
GPG key ID: B4087E510E98B164
7 changed files with 103 additions and 29 deletions
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27
compiler/rustc_ast/src/token.rs
View file

@ -784,33 +784,6 @@ impl Nonterminal {
NtTT(tt) => tt.span(),
}
}
/// This nonterminal looks like some specific enums from
/// `proc-macro-hack` and `procedural-masquerade` crates.
/// We need to maintain some special pretty-printing behavior for them due to incorrect
/// asserts in old versions of those crates and their wide use in the ecosystem.
/// See issue #73345 for more details.
/// FIXME(#73933): Remove this eventually.
pub fn pretty_printing_compatibility_hack(&self) -> bool {
let item = match self {
NtItem(item) => item,
NtStmt(stmt) => match &stmt.kind {
ast::StmtKind::Item(item) => item,
_ => return false,
},
_ => return false,
};
let name = item.ident.name;
if name == sym::ProceduralMasqueradeDummyType || name == sym::ProcMacroHack {
if let ast::ItemKind::Enum(enum_def, _) = &item.kind {
if let [variant] = &*enum_def.variants {
return variant.ident.name == sym::Input;
}
}
}
false
}
}
impl PartialEq for Nonterminal {

40
compiler/rustc_expand/src/base.rs
View file

@ -10,6 +10,8 @@ use rustc_attr::{self as attr, Deprecation, Stability};
use rustc_data_structures::fx::FxHashMap;
use rustc_data_structures::sync::{self, Lrc};
use rustc_errors::{DiagnosticBuilder, ErrorReported};
use rustc_lint_defs::builtin::PROC_MACRO_BACK_COMPAT;
use rustc_lint_defs::BuiltinLintDiagnostics;
use rustc_parse::{self, nt_to_tokenstream, parser, MACRO_ARGUMENTS};
use rustc_session::{parse::ParseSess, Limit, Session};
use rustc_span::def_id::DefId;
@ -1241,3 +1243,41 @@ pub fn get_exprs_from_tts(
}
Some(es)
}
/// This nonterminal looks like some specific enums from
/// `proc-macro-hack` and `procedural-masquerade` crates.
/// We need to maintain some special pretty-printing behavior for them due to incorrect
/// asserts in old versions of those crates and their wide use in the ecosystem.
/// See issue #73345 for more details.
/// FIXME(#73933): Remove this eventually.
pub(crate) fn pretty_printing_compatibility_hack(nt: &Nonterminal, sess: &ParseSess) -> bool {
let item = match nt {
Nonterminal::NtItem(item) => item,
Nonterminal::NtStmt(stmt) => match &stmt.kind {
ast::StmtKind::Item(item) => item,
_ => return false,
},
_ => return false,
};
let name = item.ident.name;
if name == sym::ProceduralMasqueradeDummyType {
if let ast::ItemKind::Enum(enum_def, _) = &item.kind {
if let [variant] = &*enum_def.variants {
if variant.ident.name == sym::Input {
sess.buffer_lint_with_diagnostic(
&PROC_MACRO_BACK_COMPAT,
item.ident.span,
ast::CRATE_NODE_ID,
"using `procedural-masquerade` crate",
BuiltinLintDiagnostics::ProcMacroBackCompat(
"The `procedural-masquerade` crate has been unnecessary since Rust 1.30.0. \
Versions of this crate below 0.1.7 will eventually stop compiling.".to_string())
);
return true;
}
}
}
}
false
}

3
compiler/rustc_expand/src/proc_macro.rs
View file

@ -90,7 +90,8 @@ impl MultiItemModifier for ProcMacroDerive {
}
_ => unreachable!(),
};
let input = if item.pretty_printing_compatibility_hack() {
let input = if crate::base::pretty_printing_compatibility_hack(&item, &ecx.sess.parse_sess)
{
TokenTree::token(token::Interpolated(Lrc::new(item)), DUMMY_SP).into()
} else {
nt_to_tokenstream(&item, &ecx.sess.parse_sess, CanSynthesizeMissingTokens::Yes)

2
compiler/rustc_expand/src/proc_macro_server.rs
View file

@ -187,7 +187,7 @@ impl FromInternal<(TreeAndSpacing, &'_ ParseSess, &'_ mut Vec<Self>)>
delimiter: Delimiter::None,
stream,
span: DelimSpan::from_single(span),
flatten: nt.pretty_printing_compatibility_hack(),
flatten: crate::base::pretty_printing_compatibility_hack(&nt, sess),
})
}
}

13
src/test/ui/proc-macro/issue-73933-procedural-masquerade.rs Normal file
View file

@ -0,0 +1,13 @@
// check-pass
// aux-build:test-macros.rs
#[macro_use]
extern crate test_macros;
#[derive(Print)]
enum ProceduralMasqueradeDummyType { //~ WARN using
//~| WARN this was previously
Input
}
fn main() {}

25
src/test/ui/proc-macro/issue-73933-procedural-masquerade.stderr Normal file
View file

@ -0,0 +1,25 @@
warning: using `procedural-masquerade` crate
--> $DIR/issue-73933-procedural-masquerade.rs:8:6
|
LL | enum ProceduralMasqueradeDummyType {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: `#[warn(proc_macro_back_compat)]` on by default
= warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
= note: for more information, see issue #83125 <https://github.com/rust-lang/rust/issues/83125>
= note: The `procedural-masquerade` crate has been unnecessary since Rust 1.30.0. Versions of this crate below 0.1.7 will eventually stop compiling.
warning: 1 warning emitted
Future incompatibility report: Future breakage date: None, diagnostic:
warning: using `procedural-masquerade` crate
--> $DIR/issue-73933-procedural-masquerade.rs:8:6
|
LL | enum ProceduralMasqueradeDummyType {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: `#[warn(proc_macro_back_compat)]` on by default
= warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
= note: for more information, see issue #83125 <https://github.com/rust-lang/rust/issues/83125>
= note: The `procedural-masquerade` crate has been unnecessary since Rust 1.30.0. Versions of this crate below 0.1.7 will eventually stop compiling.

22
src/test/ui/proc-macro/issue-73933-procedural-masquerade.stdout Normal file
View file

@ -0,0 +1,22 @@
PRINT-DERIVE INPUT (DISPLAY): enum ProceduralMasqueradeDummyType { Input, }
PRINT-DERIVE RE-COLLECTED (DISPLAY): enum ProceduralMasqueradeDummyType { Input }
PRINT-DERIVE INPUT (DEBUG): TokenStream [
Ident {
ident: "enum",
span: #0 bytes(100..104),
},
Ident {
ident: "ProceduralMasqueradeDummyType",
span: #0 bytes(105..134),
},
Group {
delimiter: Brace,
stream: TokenStream [
Ident {
ident: "Input",
span: #0 bytes(186..191),
},
],
span: #0 bytes(135..193),
},
]