Function with unparsed body is a definition
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. To solves this problem the function `isThisDeclarationADefinition` considers a function declaration as a definition if it has flag `WillHaveBody` set. This change fixes PR14785. Differential Revision: https://reviews.llvm.org/D30375 llvm-svn: 305379
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@ -1872,7 +1872,7 @@ public:
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///
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bool isThisDeclarationADefinition() const {
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return IsDeleted || IsDefaulted || Body || IsLateTemplateParsed ||
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hasDefiningAttr();
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WillHaveBody || hasDefiningAttr();
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}
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/// doesThisDeclarationHaveABody - Returns whether this specific
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@ -629,12 +629,6 @@ static bool IsKnownEmitted(Sema &S, FunctionDecl *FD) {
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// emitted, because (say) the definition could include "inline".
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FunctionDecl *Def = FD->getDefinition();
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// We may currently be parsing the body of FD, in which case
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// FD->getDefinition() will be null, but we still want to treat FD as though
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// it's a definition.
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if (!Def && FD->willHaveBody())
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Def = FD;
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if (Def &&
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!isDiscardableGVALinkage(S.getASTContext().GetGVALinkageForFunction(Def)))
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return true;
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@ -12218,6 +12218,7 @@ Decl *Sema::ActOnFinishFunctionBody(Decl *dcl, Stmt *Body,
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if (FD) {
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FD->setBody(Body);
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FD->setWillHaveBody(false);
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if (getLangOpts().CPlusPlus14) {
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if (!FD->isInvalidDecl() && Body && !FD->isDependentContext() &&
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@ -13878,6 +13878,9 @@ void Sema::SetDeclDeleted(Decl *Dcl, SourceLocation DelLoc) {
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return;
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}
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// Deleted function does not have a body.
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Fn->setWillHaveBody(false);
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if (const FunctionDecl *Prev = Fn->getPreviousDecl()) {
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// Don't consider the implicit declaration we generate for explicit
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// specializations. FIXME: Do not generate these implicit declarations.
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@ -1782,6 +1782,12 @@ Decl *TemplateDeclInstantiator::VisitFunctionDecl(FunctionDecl *D,
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Previous.clear();
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}
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if (isFriend) {
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Function->setObjectOfFriendDecl();
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if (FunctionTemplate)
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FunctionTemplate->setObjectOfFriendDecl();
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}
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SemaRef.CheckFunctionDeclaration(/*Scope*/ nullptr, Function, Previous,
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isExplicitSpecialization);
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@ -1792,7 +1798,6 @@ Decl *TemplateDeclInstantiator::VisitFunctionDecl(FunctionDecl *D,
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// If the original function was part of a friend declaration,
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// inherit its namespace state and add it to the owner.
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if (isFriend) {
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PrincipalDecl->setObjectOfFriendDecl();
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DC->makeDeclVisibleInContext(PrincipalDecl);
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bool QueuedInstantiation = false;
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@ -170,3 +170,15 @@ struct Test {
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template class Test<int>;
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}
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namespace pr14785 {
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template<typename T>
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struct Somewhat {
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void internal() const { }
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friend void operator+(int const &, Somewhat<T> const &) {} // expected-error{{redefinition of 'operator+'}}
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};
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void operator+(int const &, Somewhat<char> const &x) { // expected-note {{previous definition is here}}
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x.internal(); // expected-note{{in instantiation of template class 'pr14785::Somewhat<char>' requested here}}
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}
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}
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