From d6a7c1d47fdf68626b5535ff24bd115e4aba7d71 Mon Sep 17 00:00:00 2001
From: Aaron Hill <aa1ronham@gmail.com>
Date: Mon, 15 Mar 2021 15:54:25 -0400
Subject: [PATCH] Extend `proc_macro_back_compat` lint to
`procedural-masquerade`
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.
---
compiler/rustc_ast/src/token.rs | 27 -------------
compiler/rustc_expand/src/base.rs | 40 +++++++++++++++++++
compiler/rustc_expand/src/proc_macro.rs | 3 +-
.../rustc_expand/src/proc_macro_server.rs | 2 +-
.../issue-73933-procedural-masquerade.rs | 13 ++++++
.../issue-73933-procedural-masquerade.stderr | 25 ++++++++++++
.../issue-73933-procedural-masquerade.stdout | 22 ++++++++++
7 files changed, 103 insertions(+), 29 deletions(-)
create mode 100644 src/test/ui/proc-macro/issue-73933-procedural-masquerade.rs
create mode 100644 src/test/ui/proc-macro/issue-73933-procedural-masquerade.stderr
create mode 100644 src/test/ui/proc-macro/issue-73933-procedural-masquerade.stdout
diff --git a/compiler/rustc_ast/src/token.rs b/compiler/rustc_ast/src/token.rs
index 093f7f2668c46..7e58426d27de4 100644
--- a/compiler/rustc_ast/src/token.rs
+++ b/compiler/rustc_ast/src/token.rs
@@ -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 {
diff --git a/compiler/rustc_expand/src/base.rs b/compiler/rustc_expand/src/base.rs
index dd93fe8350e42..ce65793051837 100644
--- a/compiler/rustc_expand/src/base.rs
+++ b/compiler/rustc_expand/src/base.rs
@@ -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
+}
diff --git a/compiler/rustc_expand/src/proc_macro.rs b/compiler/rustc_expand/src/proc_macro.rs
index 8cbaa7c945a81..61b776ff2d280 100644
--- a/compiler/rustc_expand/src/proc_macro.rs
+++ b/compiler/rustc_expand/src/proc_macro.rs
@@ -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)
diff --git a/compiler/rustc_expand/src/proc_macro_server.rs b/compiler/rustc_expand/src/proc_macro_server.rs
index 837fad905800a..67edfe19da383 100644
--- a/compiler/rustc_expand/src/proc_macro_server.rs
+++ b/compiler/rustc_expand/src/proc_macro_server.rs
@@ -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),
})
}
}
diff --git a/src/test/ui/proc-macro/issue-73933-procedural-masquerade.rs b/src/test/ui/proc-macro/issue-73933-procedural-masquerade.rs
new file mode 100644
index 0000000000000..abc3d2691a307
--- /dev/null
+++ b/src/test/ui/proc-macro/issue-73933-procedural-masquerade.rs
@@ -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() {}
diff --git a/src/test/ui/proc-macro/issue-73933-procedural-masquerade.stderr b/src/test/ui/proc-macro/issue-73933-procedural-masquerade.stderr
new file mode 100644
index 0000000000000..0b930705e3510
--- /dev/null
+++ b/src/test/ui/proc-macro/issue-73933-procedural-masquerade.stderr
@@ -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.
+
diff --git a/src/test/ui/proc-macro/issue-73933-procedural-masquerade.stdout b/src/test/ui/proc-macro/issue-73933-procedural-masquerade.stdout
new file mode 100644
index 0000000000000..8edd68f8a3b84
--- /dev/null
+++ b/src/test/ui/proc-macro/issue-73933-procedural-masquerade.stdout
@@ -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),
+ },
+]