sepavloff created this revision.
While a function body is being parsed, the function declaration is not
considered
as a definition because it does not have a body yet. In some cases it leads to
incorrect interpretation, the case is presented in
https://bugs.llvm.org/show_bug.cgi?id=14785:
template<typename T> struct Somewhat {
void internal() const {}
friend void operator+(int const &, Somewhat<T> const &) {}
};
void operator+(int const &, Somewhat<char> const &x) { x.internal(); }
When statement `x.internal()` in the body of global `operator+` is parsed, the
type
of `x` must be completed, so the instantiation of `Somewhat<char>` is started.
It
instantiates the declaration of `operator+` defined inline, and makes a check
for
redefinition. The check does not detect another definition because the
declaration
of `operator+` is still not defining as does not have a body yet.
This change solves this problem by using flag `WillHaveBody`. It introduces new
semantic action `ActOnStartFunctionBody`, which set this flag so that
definitions
that do not have body (such as deleted functions) do not have this flag.
This change fixes PR14785.
The fix requires https://reviews.llvm.org/D26065 be applied otherwise
diagnostics is awful.
https://reviews.llvm.org/D30375
Files:
include/clang/AST/Decl.h
include/clang/Sema/Sema.h
lib/AST/Decl.cpp
lib/Parse/Parser.cpp
lib/Sema/SemaCUDA.cpp
lib/Sema/SemaDecl.cpp
lib/Sema/SemaTemplateInstantiateDecl.cpp
test/SemaCXX/friend2.cpp
Index: test/SemaCXX/friend2.cpp
===================================================================
--- test/SemaCXX/friend2.cpp
+++ test/SemaCXX/friend2.cpp
@@ -170,3 +170,15 @@
template class Test<int>;
}
+
+namespace pr14785 {
+template<typename T>
+struct Somewhat {
+ void internal() const { }
+ friend void operator+(int const &, Somewhat<T> const &) {} // expected-error{{redefinition of 'operator+'}}
+};
+
+void operator+(int const &, Somewhat<char> const &x) { // expected-note {{previous definition is here}}
+ x.internal(); // expected-note{{in instantiation of template class 'pr14785::Somewhat<char>' requested here}}
+}
+}
Index: lib/Sema/SemaTemplateInstantiateDecl.cpp
===================================================================
--- lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -3832,6 +3832,7 @@
SubstQualifier(*this, PatternDecl, Function, TemplateArgs);
ActOnStartOfFunctionDef(nullptr, Function);
+ ActOnStartFunctionBody(Function);
// Enter the scope of this instantiation. We don't use
// PushDeclContext because we don't have a scope.
Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp
+++ lib/Sema/SemaDecl.cpp
@@ -11804,11 +11804,6 @@
return D;
}
- // Mark this function as "will have a body eventually". This lets users to
- // call e.g. isInlineDefinitionExternallyVisible while we're still parsing
- // this function.
- FD->setWillHaveBody();
-
// If we are instantiating a generic lambda call operator, push
// a LambdaScopeInfo onto the function stack. But use the information
// that's already been calculated (ActOnLambdaExpr) to prime the current
@@ -11978,6 +11973,19 @@
return Decl;
}
+/// Semantic action called by parser when it expects that the current function
+/// definition will have a body statement.
+void Sema::ActOnStartFunctionBody(Decl *D) {
+ if (!D)
+ return;
+ if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
+ // Mark this function as "will have a body eventually". This lets users to
+ // call e.g. isInlineDefinitionExternallyVisible while we're still parsing
+ // this function.
+ FD->setWillHaveBody();
+ }
+}
+
Decl *Sema::ActOnFinishFunctionBody(Decl *D, Stmt *BodyArg) {
return ActOnFinishFunctionBody(D, BodyArg, false);
}
Index: lib/Sema/SemaCUDA.cpp
===================================================================
--- lib/Sema/SemaCUDA.cpp
+++ lib/Sema/SemaCUDA.cpp
@@ -629,12 +629,6 @@
// emitted, because (say) the definition could include "inline".
FunctionDecl *Def = FD->getDefinition();
- // We may currently be parsing the body of FD, in which case
- // FD->getDefinition() will be null, but we still want to treat FD as though
- // it's a definition.
- if (!Def && FD->willHaveBody())
- Def = FD;
-
if (Def &&
!isDiscardableGVALinkage(S.getASTContext().GetGVALinkageForFunction(Def)))
return true;
Index: lib/Parse/Parser.cpp
===================================================================
--- lib/Parse/Parser.cpp
+++ lib/Parse/Parser.cpp
@@ -1194,6 +1194,8 @@
return Actions.ActOnFinishFunctionBody(Res, nullptr, false);
}
+ Actions.ActOnStartFunctionBody(Res);
+
if (Tok.is(tok::kw_try))
return ParseFunctionTryBlock(Res, BodyScope);
Index: lib/AST/Decl.cpp
===================================================================
--- lib/AST/Decl.cpp
+++ lib/AST/Decl.cpp
@@ -2529,7 +2529,7 @@
bool FunctionDecl::isDefined(const FunctionDecl *&Definition) const {
for (auto I : redecls()) {
if (I->IsDeleted || I->IsDefaulted || I->Body || I->IsLateTemplateParsed ||
- I->hasDefiningAttr()) {
+ I->WillHaveBody || I->hasDefiningAttr()) {
Definition = I->IsDeleted ? I->getCanonicalDecl() : I;
return true;
}
Index: include/clang/Sema/Sema.h
===================================================================
--- include/clang/Sema/Sema.h
+++ include/clang/Sema/Sema.h
@@ -1873,6 +1873,7 @@
bool canSkipFunctionBody(Decl *D);
void computeNRVO(Stmt *Body, sema::FunctionScopeInfo *Scope);
+ void ActOnStartFunctionBody(Decl *Decl);
Decl *ActOnFinishFunctionBody(Decl *Decl, Stmt *Body);
Decl *ActOnFinishFunctionBody(Decl *Decl, Stmt *Body, bool IsInstantiation);
Decl *ActOnSkippedFunctionBody(Decl *Decl);
Index: include/clang/AST/Decl.h
===================================================================
--- include/clang/AST/Decl.h
+++ include/clang/AST/Decl.h
@@ -1839,7 +1839,7 @@
/// that this returns false for a defaulted function unless that function
/// has been implicitly defined (possibly as deleted).
bool isThisDeclarationADefinition() const {
- return IsDeleted || Body || IsLateTemplateParsed;
+ return IsDeleted || Body || IsLateTemplateParsed || WillHaveBody;
}
/// doesThisDeclarationHaveABody - Returns whether this specific
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