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[clang] Make 'fileScopeAsmDecl' matcher public #165319

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[clang] Make 'fileScopeAsmDecl' matcher public #165319

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48045c8
[clang] Make 'fileScopeAsmDecl' matcher public
capitan-davide Oct 29, 2025
72cd0ba
[clang-tidy] Update test for fileScopeAmsDecl
capitan-davide Oct 30, 2025
e6ac98a
[clang-tidy] Revert ASTMatcherNodeTest.cpp
capitan-davide Oct 30, 2025
9cfa021
[clang-tidy] Update documentation for 'fileScopeAsmDecl'
capitan-davide Oct 31, 2025
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9 changes: 1 addition & 8 deletions clang-tools-extra/clang-tidy/hicpp/NoAssemblerCheck.cpp
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Expand Up @@ -13,17 +13,10 @@ using namespace clang::ast_matchers;

namespace clang::tidy::hicpp {

namespace {
AST_MATCHER(VarDecl, isAsm) { return Node.hasAttr<clang::AsmLabelAttr>(); }
const ast_matchers::internal::VariadicDynCastAllOfMatcher<Decl,
FileScopeAsmDecl>
fileScopeAsmDecl; // NOLINT(readability-identifier-*) preserve clang style
} // namespace

void NoAssemblerCheck::registerMatchers(MatchFinder *Finder) {
Finder->addMatcher(asmStmt().bind("asm-stmt"), this);
Finder->addMatcher(fileScopeAsmDecl().bind("asm-file-scope"), this);
Finder->addMatcher(varDecl(isAsm()).bind("asm-var"), this);
Finder->addMatcher(varDecl(hasAttr(attr::AsmLabel)).bind("asm-var"), this);
}

void NoAssemblerCheck::check(const MatchFinder::MatchResult &Result) {
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14 changes: 14 additions & 0 deletions clang/docs/LibASTMatchersReference.html
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Expand Up @@ -825,6 +825,20 @@ <h2 id="decl-matchers">Node Matchers</h2>
</pre></td></tr>


<tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Decl.html">Decl</a>&gt;</td><td class="name" onclick="toggle('fileScopeAsmDecl0')"><a name="fileScopeAsmDecl0Anchor">fileScopeAsmDecl</a></td><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1FileScopeAsmDecl.html">FileScopeAsmDecl</a>&gt;...</td></tr>
<tr><td colspan="4" class="doc" id="fileScopeAsmDecl0"><pre>Matches top level asm declarations.

Given
__asm("nop");
void f() {
__asm("mov al, 2");
}
fileScopeAsmDecl()
matches '__asm("nop")',
but not '__asm("mov al, 2")'.
</pre></td></tr>


<tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Decl.html">Decl</a>&gt;</td><td class="name" onclick="toggle('friendDecl0')"><a name="friendDecl0Anchor">friendDecl</a></td><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1FriendDecl.html">FriendDecl</a>&gt;...</td></tr>
<tr><td colspan="4" class="doc" id="friendDecl0"><pre>Matches friend declarations.

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15 changes: 15 additions & 0 deletions clang/include/clang/ASTMatchers/ASTMatchers.h
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Expand Up @@ -2478,6 +2478,21 @@ extern const internal::VariadicDynCastAllOfMatcher<Stmt, NullStmt> nullStmt;
/// matches '__asm("mov al, 2")'
extern const internal::VariadicDynCastAllOfMatcher<Stmt, AsmStmt> asmStmt;

/// Matches top level asm declarations.
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What is the difference between top-level and not top-level asm declarations?
The __asm isn't top level?

Could we provide here example of non-top level declaration which wouldn't match

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@capitan-davide capitan-davide Oct 30, 2025 •
edited
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What is the difference between top-level and not top-level asm declarations?

You can find an example here of top-level vs non top-level (i.e., inline) assembly. This is what the ast looks like, with AsmStmt vs FileScopeAsmDecl.

The __asm isn't top level?

Yes, but I had the following issues:

  • asm C++ keyword is not supported by MSVC, also is not standard in C
  • __asm {} MSVC extension, does not work on Clang/GCC
  • __asm () Failed on AArch64 build (not supported?)
  • __asm__ GCC/Clang extension, but the most widely supported

Could we provide here example of non-top level declaration which wouldn't match

Yes, sure

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Could we provide here example of non-top level declaration which wouldn't match

Added a negative test

///
/// Given
/// \code
/// __asm("nop");
/// void f() {
/// __asm("mov al, 2");
/// }
/// \endcode
/// fileScopeAsmDecl()
/// matches '__asm("nop")',
/// but not '__asm("mov al, 2")'.
extern const internal::VariadicDynCastAllOfMatcher<Decl, FileScopeAsmDecl>
fileScopeAsmDecl;

/// Matches bool literals.
///
/// Example matches true
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2 changes: 2 additions & 0 deletions clang/lib/ASTMatchers/ASTMatchersInternal.cpp
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Expand Up @@ -954,6 +954,8 @@ const internal::VariadicDynCastAllOfMatcher<Stmt, CXXTryStmt> cxxTryStmt;
const internal::VariadicDynCastAllOfMatcher<Stmt, CXXThrowExpr> cxxThrowExpr;
const internal::VariadicDynCastAllOfMatcher<Stmt, NullStmt> nullStmt;
const internal::VariadicDynCastAllOfMatcher<Stmt, AsmStmt> asmStmt;
const internal::VariadicDynCastAllOfMatcher<Decl, FileScopeAsmDecl>
fileScopeAsmDecl;
const internal::VariadicDynCastAllOfMatcher<Stmt, CXXBoolLiteralExpr>
cxxBoolLiteral;
const internal::VariadicDynCastAllOfMatcher<Stmt, StringLiteral> stringLiteral;
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1 change: 1 addition & 0 deletions clang/lib/ASTMatchers/Dynamic/Registry.cpp
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Expand Up @@ -246,6 +246,7 @@ RegistryMaps::RegistryMaps() {
REGISTER_MATCHER(expr);
REGISTER_MATCHER(exprWithCleanups);
REGISTER_MATCHER(fieldDecl);
REGISTER_MATCHER(fileScopeAsmDecl);
REGISTER_MATCHER(fixedPointLiteral);
REGISTER_MATCHER(floatLiteral);
REGISTER_MATCHER(forCallable);
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14 changes: 11 additions & 3 deletions clang/unittests/ASTMatchers/ASTMatchersNodeTest.cpp
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Expand Up @@ -1179,6 +1179,12 @@ TEST_P(ASTMatchersTest, PredefinedExpr) {
has(stringLiteral()))));
}

TEST_P(ASTMatchersTest, FileScopeAsmDecl) {
EXPECT_TRUE(matches("__asm(\"nop\");", fileScopeAsmDecl()));
EXPECT_TRUE(
notMatches("void f() { __asm(\"mov al, 2\"); }", fileScopeAsmDecl()));
}

TEST_P(ASTMatchersTest, AsmStatement) {
EXPECT_TRUE(matches("void foo() { __asm(\"mov al, 2\"); }", asmStmt()));
}
Expand Down Expand Up @@ -2442,15 +2448,17 @@ TEST_P(ASTMatchersTest, LambdaCaptureTest_BindsToCaptureOfReferenceType) {
"int main() {"
" int a;"
" f(a);"
"}", matcher));
"}",
matcher));
EXPECT_FALSE(matches("template <class ...T> void f(T &...args) {"
" [...args = args] () mutable {"
" }();"
"}"
"int main() {"
" int a;"
" f(a);"
"}", matcher));
"}",
matcher));
}

TEST_P(ASTMatchersTest, IsDerivedFromRecursion) {
Expand Down Expand Up @@ -2628,7 +2636,7 @@ TEST(ASTMatchersTestObjC, ObjCStringLiteral) {
" [Test someFunction:@\"Ola!\"]; "
"}\n"
"@end ";
EXPECT_TRUE(matchesObjC(Objc1String, objcStringLiteral()));
EXPECT_TRUE(matchesObjC(Objc1String, objcStringLiteral()));
}

TEST(ASTMatchersTestObjC, ObjCDecls) {
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