sepavloff updated this revision to Diff 105853.
sepavloff added a comment.
Updated patch
- Remove changes that are not needed anymore,
- Function matching is implemented on recursive function instead of
TypeVisitor. It support subset of checks, which should be enough for practical
use.
- Added more comments.
https://reviews.llvm.org/D16579
Files:
include/clang/Basic/DiagnosticGroups.td
include/clang/Basic/DiagnosticSemaKinds.td
include/clang/Sema/Sema.h
lib/Sema/Sema.cpp
lib/Sema/SemaChecking.cpp
lib/Sema/SemaDecl.cpp
test/CXX/drs/dr3xx.cpp
test/CXX/drs/dr5xx.cpp
test/CXX/temp/temp.res/p3.cpp
test/SemaCXX/friend.cpp
test/SemaCXX/overload-call.cpp
Index: test/SemaCXX/overload-call.cpp
===================================================================
--- test/SemaCXX/overload-call.cpp
+++ test/SemaCXX/overload-call.cpp
@@ -574,13 +574,17 @@
// Ensure that overload resolution attempts to complete argument types when
// performing ADL.
template<typename T> struct S {
- friend int f(const S&);
+ friend int f(const S&); // expected-warning{{friend declaration 'IncompleteArg::f' depends on template parameter but is not a function template}}
+ // expected-note@-1{{declare function outside class template to suppress this warning}}
+ // expected-note@-2{{to befriend a template specialization, make sure the function template has already been declared and use '<>'}}
};
extern S<int> s;
int k = f(s);
template<typename T> struct Op {
- friend bool operator==(const Op &, const Op &);
+ friend bool operator==(const Op &, const Op &); // expected-warning{{friend declaration 'IncompleteArg::operator==' depends on template parameter but is not a function template}}
+ // expected-note@-1{{declare function outside class template to suppress this warning}}
+ // expected-note@-2{{to befriend a template specialization, make sure the function template has already been declared and use '<>'}}
};
extern Op<char> op;
bool b = op == op;
Index: test/SemaCXX/friend.cpp
===================================================================
--- test/SemaCXX/friend.cpp
+++ test/SemaCXX/friend.cpp
@@ -388,3 +388,116 @@
friend void f(void *p = 0) {} // expected-error {{must be the only}}
};
}
+
+template<typename T> void pr23342_func(T x);
+template<typename T>
+struct pr23342_C1 {
+ friend void pr23342_func<>(T x);
+ friend bool func(T x); // expected-warning{{friend declaration 'func' depends on template parameter but is not a function template}}
+ // expected-note@-1{{declare function outside class template to suppress this warning}}
+ // expected-note@-2{{to befriend a template specialization, make sure the function template has already been declared and use '<>'}}
+ friend bool func2(int x);
+ template<typename T2> friend bool func3(T2 x);
+ friend T func4(); // expected-warning{{friend declaration 'func4' depends on template parameter but is not a function template}}
+ // expected-note@-1{{declare function outside class template to suppress this warning}}
+ // expected-note@-2{{to befriend a template specialization, make sure the function template has already been declared and use '<>'}}
+};
+
+namespace pr23342 {
+
+template<typename T>
+struct C1 {
+ friend void pr23342_func<>(T x);
+ friend bool func(T x); // expected-warning{{friend declaration 'pr23342::func' depends on template parameter but is not a function template}}
+ // expected-note@-1{{declare function outside class template to suppress this warning}}
+ // expected-note@-2{{to befriend a template specialization, make sure the function template has already been declared and use '<>'}}
+ friend bool func2(int x);
+ template<typename T2> friend bool func3(T2 x);
+ friend T func4(); // expected-warning{{friend declaration 'pr23342::func4' depends on template parameter but is not a function template}}
+ // expected-note@-1{{declare function outside class template to suppress this warning}}
+ // expected-note@-2{{to befriend a template specialization, make sure the function template has already been declared and use '<>'}}
+};
+
+template <typename T>
+struct Arg {
+ friend bool operator==(const Arg& lhs, T rhs) {
+ return false;
+ }
+ friend bool operator!=(const Arg& lhs, T rhs); // expected-warning{{friend declaration 'pr23342::operator!=' depends on template parameter but is not a function template}}
+ // expected-note@-1{{to befriend a template specialization, make sure the function template has already been declared and use '<>'}}
+};
+template <typename T>
+bool operator!=(const Arg<T>& lhs, T rhs) {
+ return true;
+}
+bool foo() {
+ Arg<int> arg;
+ return (arg == 42) || (arg != 42);
+}
+
+
+template<typename T> class C0 {
+ friend void func0(C0<T> &); // expected-warning{{friend declaration 'pr23342::func0' depends on template parameter but is not a function template}}
+ // expected-note@-1{{declare function outside class template to suppress this warning}}
+ // expected-note@-2{{to befriend a template specialization, make sure the function template has already been declared and use '<>'}}
+};
+
+template<typename T> class C0a {
+ friend void func0a(C0a<T> &); // expected-warning{{friend declaration 'pr23342::func0a' depends on template parameter but is not a function template}}
+ // expected-note@-1{{declare function outside class template to suppress this warning}}
+ // expected-note@-2{{to befriend a template specialization, make sure the function template has already been declared and use '<>'}}
+};
+void func0a(C0a<int> x);
+void func0a(C0a<int> *x);
+void func0a(const C0a<int> &x);
+int func0a(C0a<int> &x);
+
+template<typename T> class C0b {
+ friend void func0b(C0b<T> &x);
+};
+void func0b(C0b<int> &x);
+
+
+template<typename T> class C1a {
+ friend void func1a(T x, C1a<T> &y); // expected-warning{{friend declaration 'pr23342::func1a' depends on template parameter but is not a function template}}
+ // expected-note@-1{{declare function outside class template to suppress this warning}}
+ // expected-note@-2{{to befriend a template specialization, make sure the function template has already been declared and use '<>'}}
+};
+void func1a(char x, C1a<int> &y);
+
+template<typename T> class C1b {
+ friend void func1b(T x, C1b<T> &y);
+};
+void func1b(int x, C1b<int> &y);
+
+
+template<typename T> class C2a {
+ friend void func2a(C2a<T> &); // expected-warning{{friend declaration 'pr23342::func2a' depends on template parameter but is not a function template}}
+ // expected-note@-1{{declare function outside class template to suppress this warning}}
+ // expected-note@-2{{to befriend a template specialization, make sure the function template has already been declared and use '<>'}}
+};
+template<typename T>
+void func2a(const C2a<T> &x);
+
+
+template<typename T> class C2b {
+ friend void func2b(C2b<T> &); // expected-warning{{friend declaration 'pr23342::func2b' depends on template parameter but is not a function template}}
+ // expected-note@-1{{to befriend a template specialization, make sure the function template has already been declared and use '<>'}};
+};
+template<typename T>
+void func2b(C2b<T> &x);
+
+template<typename T> class C2c;
+template<typename T>
+void func2c(C2c<T> &x);
+template<typename T> class C2c {
+ friend void func2c<>(C2c<T> &);
+};
+
+template<typename T> class C3 {
+ friend void func3(T &);
+};
+void func3(int &);
+template<typename T> void func3(T &);
+
+}
Index: test/CXX/temp/temp.res/p3.cpp
===================================================================
--- test/CXX/temp/temp.res/p3.cpp
+++ test/CXX/temp/temp.res/p3.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -verify %s -std=c++11
+// RUN: %clang_cc1 -verify %s -std=c++11 -Wno-non-template-friend
template<typename T> struct A {
template<typename U> struct B;
Index: test/CXX/drs/dr5xx.cpp
===================================================================
--- test/CXX/drs/dr5xx.cpp
+++ test/CXX/drs/dr5xx.cpp
@@ -587,8 +587,12 @@
namespace dr557 { // dr557: yes
template<typename T> struct S {
- friend void f(S<T> *);
- friend void g(S<S<T> > *);
+ friend void f(S<T> *); // expected-warning{{friend declaration 'dr557::f' depends on template parameter but is not a function template}}
+ // expected-note@-1{{declare function outside class template to suppress this warning}}
+ // expected-note@-2{{to befriend a template specialization, make sure the function template has already been declared and use '<>'}}
+ friend void g(S<S<T> > *); // expected-warning{{friend declaration 'dr557::g' depends on template parameter but is not a function template}}
+ // expected-note@-1{{declare function outside class template to suppress this warning}}
+ // expected-note@-2{{to befriend a template specialization, make sure the function template has already been declared and use '<>'}}
};
void x(S<int> *p, S<S<int> > *q) {
f(p);
Index: test/CXX/drs/dr3xx.cpp
===================================================================
--- test/CXX/drs/dr3xx.cpp
+++ test/CXX/drs/dr3xx.cpp
@@ -291,7 +291,9 @@
template void g(N::A<0>::B<0>);
namespace N {
- template<typename> struct I { friend bool operator==(const I&, const I&); };
+ template<typename> struct I { friend bool operator==(const I&, const I&); }; // expected-warning{{friend declaration 'dr321::N::operator==' depends on template parameter but is not a function template}}
+ // expected-note@-1{{declare function outside class template to suppress this warning}}
+ // expected-note@-2{{to befriend a template specialization, make sure the function template has already been declared and use '<>'}}
}
N::I<int> i, j;
bool x = i == j;
Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp
+++ lib/Sema/SemaDecl.cpp
@@ -9155,6 +9155,25 @@
AddToScope = false;
}
+ // If this is a friend function declaration inside a template class and the
+ // function depends on the template parameter as in:
+ //
+ // template<typename T> class C {
+ // friend void func(T &x);
+ // };
+ //
+ // store it in the Sema. Later on such declaration will be checked if it is
+ // a misprint of a function template.
+ if (isFriend && !NewFD->isInvalidDecl()) {
+ if (TemplateParamLists.empty() &&
+ !DC->isRecord() &&
+ !isFunctionTemplateSpecialization &&
+ NewFD->getType()->isDependentType() &&
+ !NewFD->isThisDeclarationADefinition()) {
+ FriendsOfTemplates.push_back(NewFD);
+ }
+ }
+
return NewFD;
}
Index: lib/Sema/SemaChecking.cpp
===================================================================
--- lib/Sema/SemaChecking.cpp
+++ lib/Sema/SemaChecking.cpp
@@ -12191,3 +12191,203 @@
_2, _3, _4));
}
+
+namespace {
+/// Helper class used to check if a friend declaration may refer to another
+/// function declaration.
+///
+/// The class is used to compare two function declarations, one is a friend
+/// function declared in template class, the other is a function with the same
+/// name declared at file level.
+///
+/// The class is used to produce appropriate warning if friend function declared
+/// in a template class depends on that class template parameters.
+///
+class FunctionMatcher {
+ ASTContext &Ctx;
+ std::map<const TemplateTypeParmType *, QualType> TemplParamMapping;
+
+ bool match(QualType TFriend, QualType TFunc) {
+ if (TFriend == TFunc)
+ return true;
+ if (TFriend.getQualifiers() != TFunc.getQualifiers())
+ return false;
+ if (auto FrT = TFriend->getAs<TemplateTypeParmType>()) {
+ if (auto FT = TFunc->getAs<TemplateTypeParmType>())
+ return FrT->getDepth() == FT->getDepth() &&
+ FrT->getIndex() == FT->getIndex();
+
+ const TemplateTypeParmType *CanonFrTParm = cast<TemplateTypeParmType>(
+ FrT->getCanonicalTypeUnqualified().getTypePtr());
+ CanQualType CanonFT = TFunc->getCanonicalTypeUnqualified();
+ auto Ptr = TemplParamMapping.find(CanonFrTParm);
+ if (Ptr != TemplParamMapping.end())
+ return Ptr->second == CanonFT;
+ TemplParamMapping[CanonFrTParm] = CanonFT;
+ return true;
+ }
+ if (auto FrPT = TFriend->getAs<PointerType>()) {
+ if (auto PT = TFunc->getAs<PointerType>())
+ return match(FrPT->getPointeeType(), PT->getPointeeType());
+ return false;
+ }
+ if (auto FrLR = TFriend->getAs<LValueReferenceType>()) {
+ if (auto LR = TFunc->getAs<LValueReferenceType>())
+ return match(FrLR->getPointeeType(), LR->getPointeeType());
+ return false;
+ }
+ if (auto FrRR = TFriend->getAs<RValueReferenceType>()) {
+ if (auto RR = TFunc->getAs<RValueReferenceType>())
+ return match(FrRR->getPointeeType(), RR->getPointeeType());
+ return false;
+ }
+ if (auto FrT = TFriend->getAs<InjectedClassNameType>()) {
+ QualType FrT2 = Ctx.getQualifiedType(FrT->getInjectedSpecializationType(),
+ TFriend.getQualifiers());
+ return match(FrT2, TFunc);
+ }
+ if (auto FrT = TFriend->getAs<FunctionProtoType>()) {
+ if (auto FT = TFunc->getAs<FunctionProtoType>()) {
+ if (FrT->getNumParams() != FT->getNumParams())
+ return false;
+ for (unsigned I = 0, E = FT->getNumParams(); I < E; ++I) {
+ if (!match(FrT->getParamType(I), FT->getParamType(I)))
+ return false;
+ }
+ return match(FrT->getReturnType(), FT->getReturnType());
+ }
+ return false;
+ }
+ if (auto *FrT = TFriend->getAs<TemplateSpecializationType>()) {
+ if (auto FT = TFunc->getAs<TemplateSpecializationType>()) {
+ TemplateName FrTN = FrT->getTemplateName();
+ TemplateName FTN = FT->getTemplateName();
+ if (FrTN.getKind() != TemplateName::Template ||
+ FrTN.getKind() != FTN.getKind())
+ return false;
+ if (FrTN.isInstantiationDependent() || FTN.isInstantiationDependent())
+ return false;
+ const Decl *FrD = FrTN.getAsTemplateDecl()->getCanonicalDecl();
+ const Decl *FD = FTN.getAsTemplateDecl()->getCanonicalDecl();
+ if (FrD != FD)
+ return false;
+
+ auto IFrT = FrT->begin(), EFrT = FrT->end();
+ auto IFT = FT->begin();
+ for (; IFrT != EFrT; ++IFrT, ++IFT) {
+ assert(IFT != FT->end());
+ const TemplateArgument &FrTA = *IFrT;
+ const TemplateArgument &FTA = *IFT;
+ if (FrTA.getKind() != FTA.getKind())
+ return false;
+ if (FrTA.getKind() == TemplateArgument::Type) {
+ QualType FrTy = FrTA.getAsType();
+ QualType FTy = FTA.getAsType();
+ if (!match(FrTy, FTy))
+ return false;
+ } else if (FrTA.getKind() == TemplateArgument::Integral) {
+ if (FrTA.getIntegralType() != FTA.getIntegralType())
+ return false;
+ llvm::APSInt FrV = FrTA.getAsIntegral();
+ llvm::APSInt FV = FTA.getAsIntegral();
+ if (FrV != FV)
+ return false;
+ } else
+ return false;
+ }
+ return true;
+ }
+ return false;
+ }
+
+ return false;
+ }
+
+public:
+ FunctionMatcher (ASTContext &Ctx) : Ctx(Ctx) {}
+
+ bool isPossibleMatch(FunctionDecl *FrD, FunctionDecl *F) {
+ TemplParamMapping.clear();
+ return match(FrD->getType(), F->getType());
+ }
+
+ bool isPossibleMatch(FunctionDecl *FrD, FunctionTemplateDecl *F) {
+ TemplParamMapping.clear();
+ FunctionDecl *Pattern = F->getTemplatedDecl();
+ return match(FrD->getType(), Pattern->getType());
+ }
+};
+}
+
+/// Given a friend function declaration checks if it might be misused.
+static void checkDependentFriend(Sema &S, FunctionDecl *FriendD) {
+ if (FriendD->isInvalidDecl())
+ return;
+
+ // Scan all function and function template declarations with the same name as
+ // the specified friend function to see if some of them could be referenced in
+ // the friend declaration.
+ LookupResult FRes(S, FriendD->getNameInfo(), Sema::LookupOrdinaryName);
+ if (S.LookupQualifiedName(FRes, FriendD->getDeclContext())) {
+
+ // First check for suitable functions that uses particular specialization of
+ // parameter type, for example:
+ //
+ // template<typename T> class C {
+ // friend void func(T &x);
+ // };
+ // void func(int &x);
+ //
+ // Presence of such function can be considered as an evidence that the
+ // friend function is dependent intentionally. No warning in this case.
+ for (NamedDecl *D : FRes) {
+ if (D->isInvalidDecl())
+ continue;
+ if (auto *FD = dyn_cast<FunctionDecl>(D)) {
+ if (FunctionMatcher(S.getASTContext()).isPossibleMatch(FriendD, FD))
+ return;
+ }
+ }
+
+ // Next check if there is suitable function template, like:
+ //
+ // template<typename T> class C {
+ // friend void func(T &x);
+ // };
+ // template<typename T> void func(T &x);
+ //
+ // If such template exists, issue warning and propose the template as a
+ // friend.
+ for (NamedDecl *D : FRes) {
+ if (D->isInvalidDecl())
+ continue;
+ if (auto *FTD = dyn_cast<FunctionTemplateDecl>(D))
+ if (FunctionMatcher(S.getASTContext()).isPossibleMatch(FriendD, FTD)) {
+ // Appropriate function template is found.
+ S.Diag(FriendD->getLocation(), diag::warn_non_template_friend)
+ << FriendD;
+ SourceLocation NameLoc = FriendD->getNameInfo().getLocEnd();
+ SourceLocation PastName = S.getLocForEndOfToken(NameLoc);
+ S.Diag(PastName, diag::note_befriend_template)
+ << FixItHint::CreateInsertion(PastName, "<>");
+ return;
+ }
+ }
+ }
+
+ // No appropriate function or function template was found, so issue generic
+ // warning.
+ S.Diag(FriendD->getLocation(), diag::warn_non_template_friend) << FriendD;
+ S.Diag(FriendD->getLocation(), diag::note_add_template_friend_decl);
+ S.Diag(FriendD->getLocation(), diag::note_befriend_template);
+}
+
+
+void Sema::checkDependentFriends() {
+ for (FunctionDecl *FriendD : FriendsOfTemplates) {
+ if (FriendD->getType()->isDependentType() &&
+ !FriendD->isThisDeclarationADefinition())
+ checkDependentFriend(*this, FriendD);
+ }
+ FriendsOfTemplates.clear();
+}
Index: lib/Sema/Sema.cpp
===================================================================
--- lib/Sema/Sema.cpp
+++ lib/Sema/Sema.cpp
@@ -764,6 +764,7 @@
LateTemplateParserCleanup(OpaqueParser);
CheckDelayedMemberExceptionSpecs();
+ checkDependentFriends();
}
DiagnoseUnterminatedPragmaAttribute();
Index: include/clang/Sema/Sema.h
===================================================================
--- include/clang/Sema/Sema.h
+++ include/clang/Sema/Sema.h
@@ -10318,6 +10318,27 @@
/// attempts to add itself into the container
void CheckObjCCircularContainer(ObjCMessageExpr *Message);
+ /// Set of file level friend function declared in template classes and
+ /// dependent on the template parameter.
+ ///
+ /// It is kept to check, if friend function declaration in the code like:
+ /// \code
+ /// template<typename T> class C {
+ /// friend void func(T &x);
+ /// };
+ /// \endcode
+ ///
+ /// is actually intended to be:
+ ///
+ /// \code
+ /// template<typename T2> friend void func(T2 &x);
+ /// \endcode
+ SmallVector<FunctionDecl *, 16> FriendsOfTemplates;
+
+ /// Check dependent friend functions for misinterpretation as function
+ /// templates.
+ void checkDependentFriends();
+
void AnalyzeDeleteExprMismatch(const CXXDeleteExpr *DE);
void AnalyzeDeleteExprMismatch(FieldDecl *Field, SourceLocation DeleteLoc,
bool DeleteWasArrayForm);
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -1271,6 +1271,13 @@
"enclosing namespace is a Microsoft extension; add a nested name specifier">,
InGroup<MicrosoftUnqualifiedFriend>;
def err_pure_friend : Error<"friend declaration cannot have a pure-specifier">;
+def warn_non_template_friend : Warning<"friend declaration %q0 depends on "
+ "template parameter but is not a function template">,
+ InGroup<NonTemplateFriend>;
+def note_add_template_friend_decl : Note<"declare function outside class "
+ "template to suppress this warning">;
+def note_befriend_template : Note<"to befriend a template specialization, "
+ "make sure the function template has already been declared and use '<>'">;
def err_invalid_member_in_interface : Error<
"%select{data member |non-public member function |static member function |"
Index: include/clang/Basic/DiagnosticGroups.td
===================================================================
--- include/clang/Basic/DiagnosticGroups.td
+++ include/clang/Basic/DiagnosticGroups.td
@@ -306,6 +306,7 @@
def InitializerOverrides : DiagGroup<"initializer-overrides">;
def NonNull : DiagGroup<"nonnull">;
def NonPODVarargs : DiagGroup<"non-pod-varargs">;
+def NonTemplateFriend : DiagGroup<"non-template-friend">;
def ClassVarargs : DiagGroup<"class-varargs", [NonPODVarargs]>;
def : DiagGroup<"nonportable-cfstrings">;
def NonVirtualDtor : DiagGroup<"non-virtual-dtor">;
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