https://github.com/temyurchenko updated
https://github.com/llvm/llvm-project/pull/93913
>From 9b18a5c4132cf093fc9b32f6b4dcfe406d485e3d Mon Sep 17 00:00:00 2001
From: Artem Yurchenko <artemyurche...@zoho.com>
Date: Thu, 6 Jun 2024 20:20:19 -0400
Subject: [PATCH] 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 | 26 ++++++++++++++++---
clang/lib/Sema/SemaDecl.cpp | 2 +-
clang/lib/Sema/SemaExpr.cpp | 2 +-
.../Clang/ClangExpressionParser.cpp | 2 +-
.../Clang/NameSearchContext.cpp | 3 ++-
5 files changed, 27 insertions(+), 8 deletions(-)
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 1f19dadafa44e..ebaeed0e818e1 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -576,13 +576,19 @@ 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()))
+static bool isUnbracedLanguageLinkage(const DeclContext *DC) {
+ if (!DC)
+ return false;
+ if (const auto *SD = dyn_cast<LinkageSpecDecl>(DC))
if (!SD->hasBraces())
return true;
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 +650,7 @@ LinkageComputer::getLVForNamespaceScopeDecl(const NamedDecl
*D,
if (Var->getStorageClass() != SC_Extern &&
Var->getStorageClass() != SC_PrivateExtern &&
- !isSingleLineLanguageLinkage(*Var))
+ !hasUnbracedLanguageLinkage(*Var))
return LinkageInfo::internal();
}
@@ -2133,6 +2139,12 @@ 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 +2328,7 @@ 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 +3053,12 @@ 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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