[clang] 5e28af0 - [C] Fix parsing of [[clang::assume]] (#141747)
via cfe-commits
cfe-commits at lists.llvm.org
Wed May 28 07:07:18 PDT 2025
Author: Aaron Ballman
Date: 2025-05-28T10:07:14-04:00
New Revision: 5e28af04f32455f93975e227d08f502faa45247c
URL: https://github.com/llvm/llvm-project/commit/5e28af04f32455f93975e227d08f502faa45247c
DIFF: https://github.com/llvm/llvm-project/commit/5e28af04f32455f93975e227d08f502faa45247c.diff
LOG: [C] Fix parsing of [[clang::assume]] (#141747)
The assumption attribute is exposed with a Clang spelling, which means
we support __attribute__((assume)) as well as [[clang::assume]] as
spellings for the attribute.
In C++, the [[clang::assume]] spelling worked as expected. In C, that
spelling would emit an "unknown attribute ignored" diagnostic. This was
happening because we were failing to pass in the scope name and source
location when creating the attribute. In C++, this worked by chance
because [[assume]] is a known attribute in C++. But in C, where there is
thankfully no [[assume]] standard attribute, the lack of a scope meant
we would set the attribute kind to "unknown".
Added:
clang/test/Sema/assume.c
Modified:
clang/docs/ReleaseNotes.rst
clang/include/clang/Parse/Parser.h
clang/lib/Parse/ParseDecl.cpp
clang/lib/Parse/ParseDeclCXX.cpp
Removed:
################################################################################
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index df8e035a65109..b21b683fb1360 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -226,6 +226,9 @@ C Language Changes
- Added the existing ``-Wduplicate-decl-specifier`` diagnostic, which is on by
default, to ``-Wc++-compat`` because duplicated declaration specifiers are
not valid in C++.
+- The ``[[clang::assume()]]`` attribute is now correctly recognized in C. The
+ ``__attribute__((assume()))`` form has always been supported, so the fix is
+ specific to the attribute syntax used.
C2y Feature Support
^^^^^^^^^^^^^^^^^^^
diff --git a/clang/include/clang/Parse/Parser.h b/clang/include/clang/Parse/Parser.h
index e6492b81dfff8..c4bef4729fd36 100644
--- a/clang/include/clang/Parse/Parser.h
+++ b/clang/include/clang/Parse/Parser.h
@@ -3037,11 +3037,11 @@ class Parser : public CodeCompletionHandler {
/// Parse the argument to C++23's [[assume()]] attribute. Returns true on
/// error.
- bool ParseCXXAssumeAttributeArg(ParsedAttributes &Attrs,
- IdentifierInfo *AttrName,
- SourceLocation AttrNameLoc,
- SourceLocation *EndLoc,
- ParsedAttr::Form Form);
+ bool
+ ParseCXXAssumeAttributeArg(ParsedAttributes &Attrs, IdentifierInfo *AttrName,
+ SourceLocation AttrNameLoc,
+ IdentifierInfo *ScopeName, SourceLocation ScopeLoc,
+ SourceLocation *EndLoc, ParsedAttr::Form Form);
/// Try to parse an 'identifier' which appears within an attribute-token.
///
diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index f7eb56426f6de..d6c36616bab47 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -676,7 +676,8 @@ void Parser::ParseGNUAttributeArgs(
Form);
return;
} else if (AttrKind == ParsedAttr::AT_CXXAssume) {
- ParseCXXAssumeAttributeArg(Attrs, AttrName, AttrNameLoc, EndLoc, Form);
+ ParseCXXAssumeAttributeArg(Attrs, AttrName, AttrNameLoc, ScopeName,
+ ScopeLoc, EndLoc, Form);
return;
}
@@ -734,7 +735,8 @@ unsigned Parser::ParseClangAttributeArgs(
break;
case ParsedAttr::AT_CXXAssume:
- ParseCXXAssumeAttributeArg(Attrs, AttrName, AttrNameLoc, EndLoc, Form);
+ ParseCXXAssumeAttributeArg(Attrs, AttrName, AttrNameLoc, ScopeName,
+ ScopeLoc, EndLoc, Form);
break;
}
return !Attrs.empty() ? Attrs.begin()->getNumArgs() : 0;
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index a665487a2f87d..2cf33a856c4f4 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -4452,11 +4452,10 @@ static bool IsBuiltInOrStandardCXX11Attribute(IdentifierInfo *AttrName,
}
}
-bool Parser::ParseCXXAssumeAttributeArg(ParsedAttributes &Attrs,
- IdentifierInfo *AttrName,
- SourceLocation AttrNameLoc,
- SourceLocation *EndLoc,
- ParsedAttr::Form Form) {
+bool Parser::ParseCXXAssumeAttributeArg(
+ ParsedAttributes &Attrs, IdentifierInfo *AttrName,
+ SourceLocation AttrNameLoc, IdentifierInfo *ScopeName,
+ SourceLocation ScopeLoc, SourceLocation *EndLoc, ParsedAttr::Form Form) {
assert(Tok.is(tok::l_paren) && "Not a C++11 attribute argument list");
BalancedDelimiterTracker T(*this, tok::l_paren);
T.consumeOpen();
@@ -4498,8 +4497,8 @@ bool Parser::ParseCXXAssumeAttributeArg(ParsedAttributes &Attrs,
ArgsUnion Assumption = Res.get();
auto RParen = Tok.getLocation();
T.consumeClose();
- Attrs.addNew(AttrName, SourceRange(AttrNameLoc, RParen), nullptr,
- SourceLocation(), &Assumption, 1, Form);
+ Attrs.addNew(AttrName, SourceRange(AttrNameLoc, RParen), ScopeName, ScopeLoc,
+ &Assumption, 1, Form);
if (EndLoc)
*EndLoc = RParen;
@@ -4565,7 +4564,8 @@ bool Parser::ParseCXX11AttributeArgs(
ScopeName, ScopeLoc, Form);
// So does C++23's assume() attribute.
else if (!ScopeName && AttrName->isStr("assume")) {
- if (ParseCXXAssumeAttributeArg(Attrs, AttrName, AttrNameLoc, EndLoc, Form))
+ if (ParseCXXAssumeAttributeArg(Attrs, AttrName, AttrNameLoc, nullptr,
+ SourceLocation{}, EndLoc, Form))
return true;
NumArgs = 1;
} else
diff --git a/clang/test/Sema/assume.c b/clang/test/Sema/assume.c
new file mode 100644
index 0000000000000..07a5490addfaf
--- /dev/null
+++ b/clang/test/Sema/assume.c
@@ -0,0 +1,25 @@
+// RUN: %clang_cc1 -std=c23 %s -verify
+
+// Validate that the attribute works in C.
+static_assert(!__has_c_attribute(assume));
+static_assert(__has_c_attribute(clang::assume));
+static_assert(__has_attribute(assume));
+
+void test(int n) {
+ // Smoke test.
+ __attribute__((assume(true)));
+ [[clang::assume(true)]];
+
+ // Test diagnostics
+ __attribute__((assume)); // expected-error {{'assume' attribute takes one argument}}
+ __attribute__((assume())); // expected-error {{expected expression}}
+ [[clang::assume]]; // expected-error {{'assume' attribute takes one argument}}
+ [[clang::assume()]]; // expected-error {{expected expression}}
+
+ __attribute__((assume(n++))); // expected-warning {{assumption is ignored because it contains (potential) side-effects}}
+ [[clang::assume(n++)]]; // expected-warning {{assumption is ignored because it contains (potential) side-effects}}
+
+ [[clang::assume(true)]] int x; // expected-error {{'assume' attribute cannot be applied to a declaration}}
+ __attribute__((assume(true))) int y; // expected-error {{'assume' attribute cannot be applied to a declaration}}
+}
+
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