[Lldb-commits] [clang] [lldb] [clang][AST] fix ast-print of extern <lang> with >=2 declarators, fixed (PR #93913)
Artem Yurchenko via lldb-commits
lldb-commits at lists.llvm.org
Tue Jun 18 09:04:17 PDT 2024
https://github.com/temyurchenko updated https://github.com/llvm/llvm-project/pull/93913
>From 410c7ba9fb7667dabdfbc48fdbda427401ca8df0 Mon Sep 17 00:00:00 2001
From: Artem Yurchenko <44875844+temyurchenko at users.noreply.github.com>
Date: Thu, 30 May 2024 16:18:47 -0400
Subject: [PATCH 1/2] [clang][AST] fix ast-print of `extern <lang>` with >=2
declarators (#93131)
Problem: the printer used to ignore all but the first declarator for
unbraced language linkage declarators. Furthemore, that one would
be printed without the final semicolon.
Solution: for unbraced case we traverse all declarators via
`VisitDeclContext`. Furthermore, in appropriate visitors we query
for whether they are a part of the unbraced extern language linkage
spec, and if so, print appropriately.
---
clang/lib/AST/DeclPrinter.cpp | 55 ++++++++++++++-----
clang/test/AST/ast-print-language-linkage.cpp | 31 +++++++++++
2 files changed, 72 insertions(+), 14 deletions(-)
create mode 100644 clang/test/AST/ast-print-language-linkage.cpp
diff --git a/clang/lib/AST/DeclPrinter.cpp b/clang/lib/AST/DeclPrinter.cpp
index 0cf4e64f83b8d..9250a7f6eceb2 100644
--- a/clang/lib/AST/DeclPrinter.cpp
+++ b/clang/lib/AST/DeclPrinter.cpp
@@ -633,7 +633,7 @@ static void printExplicitSpecifier(ExplicitSpecifier ES, llvm::raw_ostream &Out,
Out << Proto;
}
-static void MaybePrintTagKeywordIfSupressingScopes(PrintingPolicy &Policy,
+static void maybePrintTagKeywordIfSupressingScopes(PrintingPolicy &Policy,
QualType T,
llvm::raw_ostream &Out) {
StringRef prefix = T->isClassType() ? "class "
@@ -643,6 +643,22 @@ static void MaybePrintTagKeywordIfSupressingScopes(PrintingPolicy &Policy,
Out << prefix;
}
+/// Return the language of the linkage spec of `D`, if applicable.
+///
+/// \Return - "C" if `D` has been declared with unbraced `extern "C"`
+/// - "C++" if `D` has been declared with unbraced `extern "C++"`
+/// - nullptr in any other case
+static const char *tryGetUnbracedLinkageLanguage(const Decl *D) {
+ const auto *SD = dyn_cast<LinkageSpecDecl>(D->getDeclContext());
+ if (!SD || SD->hasBraces())
+ return nullptr;
+ if (SD->getLanguage() == LinkageSpecLanguageIDs::C)
+ return "C";
+ assert(SD->getLanguage() == LinkageSpecLanguageIDs::CXX &&
+ "unknown language in linkage specification");
+ return "C++";
+}
+
void DeclPrinter::VisitFunctionDecl(FunctionDecl *D) {
if (!D->getDescribedFunctionTemplate() &&
!D->isFunctionTemplateSpecialization()) {
@@ -662,6 +678,11 @@ void DeclPrinter::VisitFunctionDecl(FunctionDecl *D) {
CXXConversionDecl *ConversionDecl = dyn_cast<CXXConversionDecl>(D);
CXXDeductionGuideDecl *GuideDecl = dyn_cast<CXXDeductionGuideDecl>(D);
if (!Policy.SuppressSpecifiers) {
+ if (const char *Lang = tryGetUnbracedLinkageLanguage(D)) {
+ // the "extern" specifier is implicit
+ assert(D->getStorageClass() == SC_None);
+ Out << "extern \"" << Lang << "\" ";
+ }
switch (D->getStorageClass()) {
case SC_None: break;
case SC_Extern: Out << "extern "; break;
@@ -807,7 +828,7 @@ void DeclPrinter::VisitFunctionDecl(FunctionDecl *D) {
}
if (!Policy.SuppressTagKeyword && Policy.SuppressScope &&
!Policy.SuppressUnwrittenScope)
- MaybePrintTagKeywordIfSupressingScopes(Policy, AFT->getReturnType(),
+ maybePrintTagKeywordIfSupressingScopes(Policy, AFT->getReturnType(),
Out);
AFT->getReturnType().print(Out, Policy, Proto);
Proto.clear();
@@ -932,6 +953,11 @@ void DeclPrinter::VisitVarDecl(VarDecl *D) {
: D->getASTContext().getUnqualifiedObjCPointerType(D->getType());
if (!Policy.SuppressSpecifiers) {
+ if (const char *Lang = tryGetUnbracedLinkageLanguage(D)) {
+ // the "extern" specifier is implicit
+ assert(D->getStorageClass() == SC_None);
+ Out << "extern \"" << Lang << "\" ";
+ }
StorageClass SC = D->getStorageClass();
if (SC != SC_None)
Out << VarDecl::getStorageClassSpecifierString(SC) << " ";
@@ -961,7 +987,7 @@ void DeclPrinter::VisitVarDecl(VarDecl *D) {
if (!Policy.SuppressTagKeyword && Policy.SuppressScope &&
!Policy.SuppressUnwrittenScope)
- MaybePrintTagKeywordIfSupressingScopes(Policy, T, Out);
+ maybePrintTagKeywordIfSupressingScopes(Policy, T, Out);
printDeclType(T, (isa<ParmVarDecl>(D) && Policy.CleanUglifiedParameters &&
D->getIdentifier())
@@ -1064,6 +1090,8 @@ void DeclPrinter::VisitNamespaceAliasDecl(NamespaceAliasDecl *D) {
void DeclPrinter::VisitEmptyDecl(EmptyDecl *D) {
prettyPrintAttributes(D);
+ if (const char *Lang = tryGetUnbracedLinkageLanguage(D))
+ Out << "extern \"" << Lang << "\";";
}
void DeclPrinter::VisitCXXRecordDecl(CXXRecordDecl *D) {
@@ -1136,22 +1164,21 @@ void DeclPrinter::VisitCXXRecordDecl(CXXRecordDecl *D) {
}
void DeclPrinter::VisitLinkageSpecDecl(LinkageSpecDecl *D) {
- const char *l;
+ if (!D->hasBraces()) {
+ VisitDeclContext(D);
+ return;
+ }
+ const char *L;
if (D->getLanguage() == LinkageSpecLanguageIDs::C)
- l = "C";
+ L = "C";
else {
assert(D->getLanguage() == LinkageSpecLanguageIDs::CXX &&
"unknown language in linkage specification");
- l = "C++";
+ L = "C++";
}
-
- Out << "extern \"" << l << "\" ";
- if (D->hasBraces()) {
- Out << "{\n";
- VisitDeclContext(D);
- Indent() << "}";
- } else
- Visit(*D->decls_begin());
+ Out << "extern \"" << L << "\" {\n";
+ VisitDeclContext(D);
+ Indent() << "}";
}
void DeclPrinter::printTemplateParameters(const TemplateParameterList *Params,
diff --git a/clang/test/AST/ast-print-language-linkage.cpp b/clang/test/AST/ast-print-language-linkage.cpp
new file mode 100644
index 0000000000000..7e4dc3f25f062
--- /dev/null
+++ b/clang/test/AST/ast-print-language-linkage.cpp
@@ -0,0 +1,31 @@
+// RUN: %clang_cc1 -ast-print %s -o - | FileCheck %s
+
+// CHECK: extern "C" int printf(const char *, ...);
+extern "C" int printf(const char *...);
+
+// CHECK: extern "C++" int f(int);
+// CHECK-NEXT: extern "C++" int g(int);
+extern "C++" int f(int), g(int);
+
+// CHECK: extern "C" char a;
+// CHECK-NEXT: extern "C" char b;
+extern "C" char a, b;
+
+// CHECK: extern "C" {
+// CHECK-NEXT: void foo();
+// CHECK-NEXT: int x;
+// CHECK-NEXT: int y;
+// CHECK-NEXT: extern short z;
+// CHECK-NEXT: }
+extern "C" {
+ void foo(void);
+ int x, y;
+ extern short z;
+}
+
+// CHECK: extern "C" {
+// CHECK-NEXT: }
+extern "C" {}
+
+// CHECK: extern "C++";
+extern "C++";
>From b9fa7fec59bc27ef32d738f78046525f4118e53d Mon Sep 17 00:00:00 2001
From: Artem Yurchenko <artemyurchenko at zoho.com>
Date: Thu, 6 Jun 2024 20:20:19 -0400
Subject: [PATCH 2/2] [clang][AST] enforce the unbraced `extern <lang>`
invariant
Quoting 9.11.8:
> A declaration directly contained in a linkage-specification is
> treated as if it contains the extern specifier (9.2.2) for the
> purpose of determining the linkage of the declared name and whether
> it is a definition. Such a declaration shall not specify a storage
> class.
So, the invariant is that function and variable declarations within an
unbraced language linkage specification have `StorageClass` set to
`SC_None`.
Problem: in several places the invariant was broken.
Solution: remove the explicit `SC_Extern` specification. Note, that my
changes result in the `extern` being implicit in some functions
that are not contained in a language linkage specification.
---
clang/lib/AST/Decl.cpp | 27 ++++++++++++++-----
clang/lib/Sema/SemaDecl.cpp | 2 +-
clang/lib/Sema/SemaExpr.cpp | 2 +-
.../Clang/ClangExpressionParser.cpp | 2 +-
.../Clang/NameSearchContext.cpp | 3 ++-
5 files changed, 26 insertions(+), 10 deletions(-)
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 1f19dadafa44e..35973d99f906d 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -576,13 +576,16 @@ template <typename T> static bool isFirstInExternCContext(T *D) {
return First->isInExternCContext();
}
-static bool isSingleLineLanguageLinkage(const Decl &D) {
- if (const auto *SD = dyn_cast<LinkageSpecDecl>(D.getDeclContext()))
- if (!SD->hasBraces())
- return true;
+static bool isUnbracedLanguageLinkage(const DeclContext *DC) {
+ if (const auto *SD = dyn_cast_if_present<LinkageSpecDecl>(DC))
+ return !SD->hasBraces();
return false;
}
+static bool hasUnbracedLanguageLinkage(const Decl &D) {
+ return isUnbracedLanguageLinkage(D.getDeclContext());
+}
+
static bool isDeclaredInModuleInterfaceOrPartition(const NamedDecl *D) {
if (auto *M = D->getOwningModule())
return M->isInterfaceOrPartition();
@@ -644,7 +647,7 @@ LinkageComputer::getLVForNamespaceScopeDecl(const NamedDecl *D,
if (Var->getStorageClass() != SC_Extern &&
Var->getStorageClass() != SC_PrivateExtern &&
- !isSingleLineLanguageLinkage(*Var))
+ !hasUnbracedLanguageLinkage(*Var))
return LinkageInfo::internal();
}
@@ -2133,6 +2136,12 @@ VarDecl::VarDecl(Kind DK, ASTContext &C, DeclContext *DC,
"ParmVarDeclBitfields too large!");
static_assert(sizeof(NonParmVarDeclBitfields) <= sizeof(unsigned),
"NonParmVarDeclBitfields too large!");
+
+ // The unbraced `extern "C"` invariant is that the storage class
+ // specifier is omitted in the source code, i.e. SC_None (but is,
+ // implicitly, `extern`).
+ assert(!isUnbracedLanguageLinkage(DC) || SC == SC_None);
+
AllBits = 0;
VarDeclBits.SClass = SC;
// Everything else is implicitly initialized to false.
@@ -2316,7 +2325,7 @@ VarDecl::isThisDeclarationADefinition(ASTContext &C) const {
// A declaration directly contained in a linkage-specification is treated
// as if it contains the extern specifier for the purpose of determining
// the linkage of the declared name and whether it is a definition.
- if (isSingleLineLanguageLinkage(*this))
+ if (hasUnbracedLanguageLinkage(*this))
return DeclarationOnly;
// C99 6.9.2p2:
@@ -3041,6 +3050,12 @@ FunctionDecl::FunctionDecl(Kind DK, ASTContext &C, DeclContext *DC,
DeclContext(DK), redeclarable_base(C), Body(), ODRHash(0),
EndRangeLoc(NameInfo.getEndLoc()), DNLoc(NameInfo.getInfo()) {
assert(T.isNull() || T->isFunctionType());
+
+ // The unbraced `extern "C"` invariant is that the storage class
+ // specifier is omitted in the source code, i.e. SC_None (but is,
+ // implicitly, `extern`).
+ assert(!isUnbracedLanguageLinkage(DC) || S == SC_None);
+
FunctionDeclBits.SClass = S;
FunctionDeclBits.IsInline = isInlineSpecified;
FunctionDeclBits.IsInlineSpecified = isInlineSpecified;
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 4b9b735f1cfb4..4e2f02ba7007a 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -2380,7 +2380,7 @@ FunctionDecl *Sema::CreateBuiltin(IdentifierInfo *II, QualType Type,
}
FunctionDecl *New = FunctionDecl::Create(Context, Parent, Loc, Loc, II, Type,
- /*TInfo=*/nullptr, SC_Extern,
+ /*TInfo=*/nullptr, SC_None,
getCurFPFeatures().isFPConstrained(),
false, Type->isFunctionProtoType());
New->setImplicit();
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 76145f291887c..60075120fe030 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -6286,7 +6286,7 @@ static FunctionDecl *rewriteBuiltinFunctionDecl(Sema *Sema, ASTContext &Context,
FunctionDecl *OverloadDecl = FunctionDecl::Create(
Context, Parent, FDecl->getLocation(), FDecl->getLocation(),
FDecl->getIdentifier(), OverloadTy,
- /*TInfo=*/nullptr, SC_Extern, Sema->getCurFPFeatures().isFPConstrained(),
+ /*TInfo=*/nullptr, SC_None, Sema->getCurFPFeatures().isFPConstrained(),
false,
/*hasPrototype=*/true);
SmallVector<ParmVarDecl*, 16> Params;
diff --git a/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp b/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
index 1dd98567f8d69..12aa1bd60bcb7 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
+++ b/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
@@ -881,7 +881,7 @@ class CodeComplete : public CodeCompleteConsumer {
else
ToInsert += "(";
raw_string_ostream OS(Description);
- F->print(OS, m_desc_policy, false);
+ F->print(OS, m_desc_policy);
OS.flush();
} else if (const VarDecl *V = dyn_cast<VarDecl>(D)) {
Description = V->getType().getAsString(m_desc_policy);
diff --git a/lldb/source/Plugins/ExpressionParser/Clang/NameSearchContext.cpp b/lldb/source/Plugins/ExpressionParser/Clang/NameSearchContext.cpp
index da59855a9f162..e02b418b1e793 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/NameSearchContext.cpp
+++ b/lldb/source/Plugins/ExpressionParser/Clang/NameSearchContext.cpp
@@ -77,7 +77,8 @@ clang::NamedDecl *NameSearchContext::AddFunDecl(const CompilerType &type,
clang::FunctionDecl *func_decl = FunctionDecl::Create(
ast, context, SourceLocation(), SourceLocation(), decl_name, qual_type,
- nullptr, SC_Extern, /*UsesFPIntrin=*/false, isInlineSpecified, hasWrittenPrototype,
+ nullptr, SC_None, /*UsesFPIntrin=*/false, isInlineSpecified,
+ hasWrittenPrototype,
isConstexprSpecified ? ConstexprSpecKind::Constexpr
: ConstexprSpecKind::Unspecified);
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