Fix PR10053: Improve diagnostics and error recovery for code which some compilers incorrectly accept due to a lack of proper support for two-phase name lookup.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@132672 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Richard Smith 2011-06-05 22:42:48 +00:00
Родитель 25a857b803
Коммит f50e88a793
5 изменённых файлов: 295 добавлений и 21 удалений

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@ -2173,6 +2173,10 @@ def err_unexpected_namespace : Error<
def err_undeclared_var_use : Error<"use of undeclared identifier %0">;
def note_dependent_var_use : Note<"must qualify identifier to find this "
"declaration in dependent base class">;
def err_not_found_by_two_phase_lookup : Error<"call to function %0 that is neither "
"visible in the template definition nor found by argument dependent lookup">;
def note_not_found_by_two_phase_lookup : Note<"%0 should be declared prior to the "
"call site%select{| or in %2| or in an associated namespace of one of its arguments}1">;
def err_undeclared_use : Error<"use of undeclared %0">;
def warn_deprecated : Warning<"%0 is deprecated">,
InGroup<DeprecatedDeclarations>;

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@ -7826,6 +7826,111 @@ void Sema::AddOverloadedCallCandidates(UnresolvedLookupExpr *ULE,
ULE->isStdAssociatedNamespace());
}
/// Attempt to recover from an ill-formed use of a non-dependent name in a
/// template, where the non-dependent name was declared after the template
/// was defined. This is common in code written for a compilers which do not
/// correctly implement two-stage name lookup.
///
/// Returns true if a viable candidate was found and a diagnostic was issued.
static bool
DiagnoseTwoPhaseLookup(Sema &SemaRef, SourceLocation FnLoc,
const CXXScopeSpec &SS, LookupResult &R,
TemplateArgumentListInfo *ExplicitTemplateArgs,
Expr **Args, unsigned NumArgs) {
if (SemaRef.ActiveTemplateInstantiations.empty() || !SS.isEmpty())
return false;
for (DeclContext *DC = SemaRef.CurContext; DC; DC = DC->getParent()) {
SemaRef.LookupQualifiedName(R, DC);
if (!R.empty()) {
R.suppressDiagnostics();
if (isa<CXXRecordDecl>(DC)) {
// Don't diagnose names we find in classes; we get much better
// diagnostics for these from DiagnoseEmptyLookup.
R.clear();
return false;
}
OverloadCandidateSet Candidates(FnLoc);
for (LookupResult::iterator I = R.begin(), E = R.end(); I != E; ++I)
AddOverloadedCallCandidate(SemaRef, I.getPair(),
ExplicitTemplateArgs, Args, NumArgs,
Candidates, false);
OverloadCandidateSet::iterator Best;
if (Candidates.BestViableFunction(SemaRef, FnLoc, Best) != OR_Success)
// No viable functions. Don't bother the user with notes for functions
// which don't work and shouldn't be found anyway.
return false;
// Find the namespaces where ADL would have looked, and suggest
// declaring the function there instead.
Sema::AssociatedNamespaceSet AssociatedNamespaces;
Sema::AssociatedClassSet AssociatedClasses;
SemaRef.FindAssociatedClassesAndNamespaces(Args, NumArgs,
AssociatedNamespaces,
AssociatedClasses);
// Never suggest declaring a function within namespace 'std'.
if (DeclContext *Std = SemaRef.getStdNamespace()) {
// Use two passes: SmallPtrSet::erase invalidates too many iterators
// to be used in the loop.
llvm::SmallVector<DeclContext*, 4> StdNamespaces;
for (Sema::AssociatedNamespaceSet::iterator
it = AssociatedNamespaces.begin(),
end = AssociatedNamespaces.end(); it != end; ++it)
if (Std->Encloses(*it))
StdNamespaces.push_back(*it);
for (unsigned I = 0; I != StdNamespaces.size(); ++I)
AssociatedNamespaces.erase(StdNamespaces[I]);
}
SemaRef.Diag(R.getNameLoc(), diag::err_not_found_by_two_phase_lookup)
<< R.getLookupName();
if (AssociatedNamespaces.empty()) {
SemaRef.Diag(Best->Function->getLocation(),
diag::note_not_found_by_two_phase_lookup)
<< R.getLookupName() << 0;
} else if (AssociatedNamespaces.size() == 1) {
SemaRef.Diag(Best->Function->getLocation(),
diag::note_not_found_by_two_phase_lookup)
<< R.getLookupName() << 1 << *AssociatedNamespaces.begin();
} else {
// FIXME: It would be useful to list the associated namespaces here,
// but the diagnostics infrastructure doesn't provide a way to produce
// a localized representation of a list of items.
SemaRef.Diag(Best->Function->getLocation(),
diag::note_not_found_by_two_phase_lookup)
<< R.getLookupName() << 2;
}
// Try to recover by calling this function.
return true;
}
R.clear();
}
return false;
}
/// Attempt to recover from ill-formed use of a non-dependent operator in a
/// template, where the non-dependent operator was declared after the template
/// was defined.
///
/// Returns true if a viable candidate was found and a diagnostic was issued.
static bool
DiagnoseTwoPhaseOperatorLookup(Sema &SemaRef, OverloadedOperatorKind Op,
SourceLocation OpLoc,
Expr **Args, unsigned NumArgs) {
DeclarationName OpName =
SemaRef.Context.DeclarationNames.getCXXOperatorName(Op);
LookupResult R(SemaRef, OpName, OpLoc, Sema::LookupOperatorName);
return DiagnoseTwoPhaseLookup(SemaRef, OpLoc, CXXScopeSpec(), R,
/*ExplicitTemplateArgs=*/0, Args, NumArgs);
}
/// Attempts to recover from a call where no functions were found.
///
/// Returns true if new candidates were found.
@ -7834,13 +7939,14 @@ BuildRecoveryCallExpr(Sema &SemaRef, Scope *S, Expr *Fn,
UnresolvedLookupExpr *ULE,
SourceLocation LParenLoc,
Expr **Args, unsigned NumArgs,
SourceLocation RParenLoc) {
SourceLocation RParenLoc,
bool EmptyLookup) {
CXXScopeSpec SS;
SS.Adopt(ULE->getQualifierLoc());
TemplateArgumentListInfo TABuffer;
const TemplateArgumentListInfo *ExplicitTemplateArgs = 0;
TemplateArgumentListInfo *ExplicitTemplateArgs = 0;
if (ULE->hasExplicitTemplateArgs()) {
ULE->copyTemplateArgumentsInto(TABuffer);
ExplicitTemplateArgs = &TABuffer;
@ -7848,7 +7954,10 @@ BuildRecoveryCallExpr(Sema &SemaRef, Scope *S, Expr *Fn,
LookupResult R(SemaRef, ULE->getName(), ULE->getNameLoc(),
Sema::LookupOrdinaryName);
if (SemaRef.DiagnoseEmptyLookup(S, SS, R, Sema::CTC_Expression))
if (!DiagnoseTwoPhaseLookup(SemaRef, Fn->getExprLoc(), SS, R,
ExplicitTemplateArgs, Args, NumArgs) &&
(!EmptyLookup ||
SemaRef.DiagnoseEmptyLookup(S, SS, R, Sema::CTC_Expression)))
return ExprError();
assert(!R.empty() && "lookup results empty despite recovery");
@ -7868,7 +7977,7 @@ BuildRecoveryCallExpr(Sema &SemaRef, Scope *S, Expr *Fn,
return ExprError();
// This shouldn't cause an infinite loop because we're giving it
// an expression with non-empty lookup results, which should never
// an expression with viable lookup results, which should never
// end up here.
return SemaRef.ActOnCallExpr(/*Scope*/ 0, NewFn.take(), LParenLoc,
MultiExprArg(Args, NumArgs), RParenLoc);
@ -7914,11 +8023,11 @@ Sema::BuildOverloadedCallExpr(Scope *S, Expr *Fn, UnresolvedLookupExpr *ULE,
AddOverloadedCallCandidates(ULE, Args, NumArgs, CandidateSet);
// If we found nothing, try to recover.
// AddRecoveryCallCandidates diagnoses the error itself, so we just
// bailout out if it fails.
// BuildRecoveryCallExpr diagnoses the error itself, so we just bail
// out if it fails.
if (CandidateSet.empty())
return BuildRecoveryCallExpr(*this, S, Fn, ULE, LParenLoc, Args, NumArgs,
RParenLoc);
RParenLoc, /*EmptyLookup=*/true);
OverloadCandidateSet::iterator Best;
switch (CandidateSet.BestViableFunction(*this, Fn->getLocStart(), Best)) {
@ -7933,12 +8042,21 @@ Sema::BuildOverloadedCallExpr(Scope *S, Expr *Fn, UnresolvedLookupExpr *ULE,
ExecConfig);
}
case OR_No_Viable_Function:
case OR_No_Viable_Function: {
// Try to recover by looking for viable functions which the user might
// have meant to call.
ExprResult Recovery = BuildRecoveryCallExpr(*this, S, Fn, ULE, LParenLoc,
Args, NumArgs, RParenLoc,
/*EmptyLookup=*/false);
if (!Recovery.isInvalid())
return Recovery;
Diag(Fn->getSourceRange().getBegin(),
diag::err_ovl_no_viable_function_in_call)
<< ULE->getName() << Fn->getSourceRange();
CandidateSet.NoteCandidates(*this, OCD_AllCandidates, Args, NumArgs);
break;
}
case OR_Ambiguous:
Diag(Fn->getSourceRange().getBegin(), diag::err_ovl_ambiguous_call)
@ -8127,6 +8245,13 @@ Sema::CreateOverloadedUnaryOp(SourceLocation OpLoc, unsigned OpcIn,
}
case OR_No_Viable_Function:
// This is an erroneous use of an operator which can be overloaded by
// a non-member function. Check for non-member operators which were
// defined too late to be candidates.
if (DiagnoseTwoPhaseOperatorLookup(*this, Op, OpLoc, Args, NumArgs))
// FIXME: Recover by calling the found function.
return ExprError();
// No viable function; fall through to handling this as a
// built-in operator, which will produce an error message for us.
break;
@ -8408,6 +8533,13 @@ Sema::CreateOverloadedBinOp(SourceLocation OpLoc,
<< BinaryOperator::getOpcodeStr(Opc)
<< Args[0]->getSourceRange() << Args[1]->getSourceRange();
} else {
// This is an erroneous use of an operator which can be overloaded by
// a non-member function. Check for non-member operators which were
// defined too late to be candidates.
if (DiagnoseTwoPhaseOperatorLookup(*this, Op, OpLoc, Args, 2))
// FIXME: Recover by calling the found function.
return ExprError();
// No viable function; try to create a built-in operation, which will
// produce an error. Then, show the non-viable candidates.
Result = CreateBuiltinBinOp(OpLoc, Opc, Args[0], Args[1]);

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@ -1,4 +1,4 @@
// RUN: %clang_cc1 -fsyntax-only -verify %s
// RUN: %clang_cc1 -fsyntax-only -verify -std=c++0x %s
typedef double A;
template<typename T> class B {
@ -129,3 +129,136 @@ namespace PR8966 {
template <class T>
const char* MyClass<T>::array [MyClass<T>::N] = { "A", "B", "C" };
}
namespace std {
inline namespace v1 {
template<typename T> struct basic_ostream;
}
namespace inner {
template<typename T> struct vector {};
}
using inner::vector;
template<typename T, typename U> struct pair {};
typedef basic_ostream<char> ostream;
extern ostream cout;
std::ostream &operator<<(std::ostream &out, const char *);
}
namespace PR10053 {
template<typename T> struct A {
T t;
A() {
f(t); // expected-error {{call to function 'f' that is neither visible in the template definition nor found by argument dependent lookup}}
}
};
void f(int&); // expected-note {{'f' should be declared prior to the call site}}
A<int> a; // expected-note {{in instantiation of member function}}
namespace N {
namespace M {
template<typename T> int g(T t) {
f(t); // expected-error {{call to function 'f' that is neither visible in the template definition nor found by argument dependent lookup}}
};
}
void f(char&); // expected-note {{'f' should be declared prior to the call site}}
}
void f(char&);
int k = N::M::g<char>(0);; // expected-note {{in instantiation of function}}
namespace O {
void f(char&); // expected-note {{candidate function not viable}}
template<typename T> struct C {
static const int n = f(T()); // expected-error {{no matching function}}
};
}
int f(double); // no note, shadowed by O::f
O::C<double> c; // expected-note {{requested here}}
// Example from www/compatibility.html
namespace my_file {
template <typename T> T Squared(T x) {
return Multiply(x, x); // expected-error {{neither visible in the template definition nor found by argument dependent lookup}}
}
int Multiply(int x, int y) { // expected-note {{should be declared prior to the call site}}
return x * y;
}
int main() {
Squared(5); // expected-note {{here}}
}
}
// Example from www/compatibility.html
namespace my_file2 {
template<typename T>
void Dump(const T& value) {
std::cout << value << "\n"; // expected-error {{neither visible in the template definition nor found by argument dependent lookup}}
}
namespace ns {
struct Data {};
}
std::ostream& operator<<(std::ostream& out, ns::Data data) { // expected-note {{should be declared prior to the call site or in namespace 'PR10053::my_file2::ns'}}
return out << "Some data";
}
void Use() {
Dump(ns::Data()); // expected-note {{here}}
}
}
namespace my_file2_a {
template<typename T>
void Dump(const T &value) {
print(std::cout, value); // expected-error 4{{neither visible in the template definition nor found by argument dependent lookup}}
}
namespace ns {
struct Data {};
}
namespace ns2 {
struct Data {};
}
std::ostream &print(std::ostream &out, int); // expected-note-re {{should be declared prior to the call site$}}
std::ostream &print(std::ostream &out, ns::Data); // expected-note {{should be declared prior to the call site or in namespace 'PR10053::my_file2_a::ns'}}
std::ostream &print(std::ostream &out, std::vector<ns2::Data>); // expected-note {{should be declared prior to the call site or in namespace 'PR10053::my_file2_a::ns2'}}
std::ostream &print(std::ostream &out, std::pair<ns::Data, ns2::Data>); // expected-note {{should be declared prior to the call site or in an associated namespace of one of its arguments}}
void Use() {
Dump(0); // expected-note {{requested here}}
Dump(ns::Data()); // expected-note {{requested here}}
Dump(std::vector<ns2::Data>()); // expected-note {{requested here}}
Dump(std::pair<ns::Data, ns2::Data>()); // expected-note {{requested here}}
}
}
namespace unary {
template<typename T>
T Negate(const T& value) {
return !value; // expected-error {{call to function 'operator!' that is neither visible in the template definition nor found by argument dependent lookup}}
}
namespace ns {
struct Data {};
}
ns::Data operator!(ns::Data); // expected-note {{should be declared prior to the call site or in namespace 'PR10053::unary::ns'}}
void Use() {
Negate(ns::Data()); // expected-note {{requested here}}
}
}
}

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@ -24,7 +24,8 @@ namespace N3 {
template<typename T, typename Result>
struct call_f0 {
void test_f0(T t) {
Result &result = f0(t); // expected-error 2{{undeclared identifier}}
Result &result = f0(t); // expected-error {{undeclared identifier}} \
expected-error {{neither visible in the template definition nor found by argument dependent lookup}}
}
};
}
@ -32,7 +33,7 @@ namespace N3 {
template struct N3::call_f0<int, char&>; // expected-note{{instantiation}}
template struct N3::call_f0<N1::X0, int&>;
short& f0(char);
short& f0(char); // expected-note {{should be declared prior to the call site}}
namespace N4 {
template<typename T, typename Result>
struct call_f0 {

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@ -459,13 +459,15 @@ int main() {
<p>Clang complains:
<pre> <b>my_file.cpp:2:10: <span class="error">error:</span> use of undeclared identifier 'Multiply'</b>
<pre> <b>my_file.cpp:2:10: <span class="error">error:</span> call to function 'Multiply' that is neither visible in the template definition nor found by argument dependent lookup</b>
return Multiply(x, x);
<span class="caret"> ^</span>
<b>my_file.cpp:10:3: <span class="note">note:</span> in instantiation of function template specialization 'Squared&lt;int&gt;' requested here</b>
Squared(5);
<span class="caret"> ^</span>
<b>my_file.cpp:5:5: <span class="note">note:</span> 'Multiply' should be declared prior to the call site</b>
int Multiply(int x, int y) {
<span class="caret"> ^</span>
</pre>
<p>The C++ standard says that unqualified names like <q>Multiply</q>
@ -516,15 +518,17 @@ void Use() {
Dump(ns::Data());
}</pre>
<p>Again, Clang complains about not finding a matching function:</p>
<p>Again, Clang complains:</p>
<pre>
<b>my_file.cpp:5:13: <span class="error">error:</span> invalid operands to binary expression ('ostream' (aka 'basic_ostream&lt;char&gt;') and 'ns::Data const')</b>
std::cout &lt;&lt; value &lt;&lt; "\n";
<span class="caret">~~~~~~~~~ ^ ~~~~~</span>
<b>my_file.cpp:17:3: <span class="note">note:</span> in instantiation of function template specialization 'Dump&lt;ns::Data&gt;' requested here</b>
Dump(ns::Data());
<span class="caret">^</span>
<pre> <b>my_file2.cpp:5:13: <span class="error">error:</span> call to function 'operator&lt;&lt;' that is neither visible in the template definition nor found by argument dependent lookup</b>
std::cout &lt;&lt; value &lt;&lt; "\n";
<span class="caret"> ^</span>
<b>my_file2.cpp:17:3: <span class="error">note:</span> in instantiation of function template specialization 'Dump&lt;ns::Data&gt;' requested here</b>
Dump(ns::Data());
<span class="caret"> ^</span>
<b>my_file2.cpp:12:15: <span class="error">note:</span> 'operator&lt;&lt;' should be declared prior to the call site or in namespace 'ns'</b>
std::ostream&amp; operator&lt;&lt;(std::ostream&amp; out, ns::Data data) {
<span class="caret"> ^</span>
</pre>
<p>Just like before, unqualified lookup didn't find any declarations