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This revision was automatically updated to reflect the committed changes.
Closed by commit rG807e418413a0: [Concepts] Fix overload resolution bug with
constrained candidates (authored by royjacobson).
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D123182/new/
https://reviews.llvm.org/D123182
Files:
clang/docs/ReleaseNotes.rst
clang/include/clang/Sema/Sema.h
clang/lib/Sema/SemaOverload.cpp
clang/lib/Sema/SemaTemplateDeduction.cpp
clang/test/CXX/temp/temp.decls/temp.fct/temp.func.order/p6.cpp
Index: clang/test/CXX/temp/temp.decls/temp.fct/temp.func.order/p6.cpp
===================================================================
--- /dev/null
+++ clang/test/CXX/temp/temp.decls/temp.fct/temp.func.order/p6.cpp
@@ -0,0 +1,49 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++20 %s
+
+struct A;
+struct B;
+
+template <typename> constexpr bool True = true;
+template <typename T> concept C = True<T>;
+
+void f(C auto &, auto &) = delete;
+template <C Q> void f(Q &, C auto &);
+
+void g(struct A *ap, struct B *bp) {
+ f(*ap, *bp);
+}
+
+template <typename T, typename U> struct X {};
+
+template <typename T, C U, typename V> bool operator==(X<T, U>, V) = delete;
+template <C T, C U, C V> bool operator==(T, X<U, V>);
+
+bool h() {
+ return X<void *, int>{} == 0;
+}
+
+namespace PR53640 {
+
+template <typename T>
+concept C = true;
+
+template <C T>
+void f(T t) {} // expected-note {{candidate function [with T = int]}}
+
+template <typename T>
+void f(const T &t) {} // expected-note {{candidate function [with T = int]}}
+
+int g() {
+ f(0); // expected-error {{call to 'f' is ambiguous}}
+}
+
+struct S {
+ template <typename T> explicit S(T) noexcept requires C<T> {} // expected-note {{candidate constructor}}
+ template <typename T> explicit S(const T &) noexcept {} // expected-note {{candidate constructor}}
+};
+
+int h() {
+ S s(4); // expected-error-re {{call to constructor of {{.*}} is ambiguous}}
+}
+
+}
Index: clang/lib/Sema/SemaTemplateDeduction.cpp
===================================================================
--- clang/lib/Sema/SemaTemplateDeduction.cpp
+++ clang/lib/Sema/SemaTemplateDeduction.cpp
@@ -5143,18 +5143,20 @@
/// candidate with a reversed parameter order. In this case, the corresponding
/// P/A pairs between FT1 and FT2 are reversed.
///
+/// \param AllowOrderingByConstraints If \c is false, don't check whether one
+/// of the templates is more constrained than the other. Default is true.
+///
/// \returns the more specialized function template. If neither
/// template is more specialized, returns NULL.
-FunctionTemplateDecl *
-Sema::getMoreSpecializedTemplate(FunctionTemplateDecl *FT1,
- FunctionTemplateDecl *FT2,
- SourceLocation Loc,
- TemplatePartialOrderingContext TPOC,
- unsigned NumCallArguments1,
- unsigned NumCallArguments2,
- bool Reversed) {
-
- auto JudgeByConstraints = [&] () -> FunctionTemplateDecl * {
+FunctionTemplateDecl *Sema::getMoreSpecializedTemplate(
+ FunctionTemplateDecl *FT1, FunctionTemplateDecl *FT2, SourceLocation Loc,
+ TemplatePartialOrderingContext TPOC, unsigned NumCallArguments1,
+ unsigned NumCallArguments2, bool Reversed,
+ bool AllowOrderingByConstraints) {
+
+ auto JudgeByConstraints = [&]() -> FunctionTemplateDecl * {
+ if (!AllowOrderingByConstraints)
+ return nullptr;
llvm::SmallVector<const Expr *, 3> AC1, AC2;
FT1->getAssociatedConstraints(AC1);
FT2->getAssociatedConstraints(AC2);
Index: clang/lib/Sema/SemaOverload.cpp
===================================================================
--- clang/lib/Sema/SemaOverload.cpp
+++ clang/lib/Sema/SemaOverload.cpp
@@ -2945,24 +2945,30 @@
}
/// FunctionParamTypesAreEqual - This routine checks two function proto types
-/// for equality of their argument types. Caller has already checked that
-/// they have same number of arguments. If the parameters are different,
+/// for equality of their parameter types. Caller has already checked that
+/// they have same number of parameters. If the parameters are different,
/// ArgPos will have the parameter index of the first different parameter.
+/// If `Reversed` is true, the parameters of `NewType` will be compared in
+/// reverse order. That's useful if one of the functions is being used as a C++20
+/// synthesized operator overload with a reversed parameter order.
bool Sema::FunctionParamTypesAreEqual(const FunctionProtoType *OldType,
const FunctionProtoType *NewType,
- unsigned *ArgPos) {
- for (FunctionProtoType::param_type_iterator O = OldType->param_type_begin(),
- N = NewType->param_type_begin(),
- E = OldType->param_type_end();
- O && (O != E); ++O, ++N) {
+ unsigned *ArgPos, bool Reversed) {
+ assert(OldType->getNumParams() == NewType->getNumParams() &&
+ "Can't compare parameters of functions with different number of "
+ "parameters!");
+ for (size_t I = 0; I < OldType->getNumParams(); I++) {
+ // Reverse iterate over the parameters of `OldType` if `Reversed` is true.
+ size_t J = Reversed ? (OldType->getNumParams() - I - 1) : I;
+
// Ignore address spaces in pointee type. This is to disallow overloading
// on __ptr32/__ptr64 address spaces.
- QualType Old = Context.removePtrSizeAddrSpace(O->getUnqualifiedType());
- QualType New = Context.removePtrSizeAddrSpace(N->getUnqualifiedType());
+ QualType Old = Context.removePtrSizeAddrSpace(OldType->getParamType(I).getUnqualifiedType());
+ QualType New = Context.removePtrSizeAddrSpace(NewType->getParamType(J).getUnqualifiedType());
if (!Context.hasSameType(Old, New)) {
if (ArgPos)
- *ArgPos = O - OldType->param_type_begin();
+ *ArgPos = I;
return false;
}
}
@@ -9584,6 +9590,32 @@
return true;
}
+/// We're allowed to use constraints partial ordering only if the candidates
+/// have the same parameter types:
+/// [temp.func.order]p6.2.2 [...] or if the function parameters that
+/// positionally correspond between the two templates are not of the same type,
+/// neither template is more specialized than the other.
+/// [over.match.best]p2.6
+/// F1 and F2 are non-template functions with the same parameter-type-lists,
+/// and F1 is more constrained than F2 [...]
+static bool canCompareFunctionConstraints(Sema &S,
+ const OverloadCandidate &Cand1,
+ const OverloadCandidate &Cand2) {
+ // FIXME: Per P2113R0 we also need to compare the template parameter lists
+ // when comparing template functions.
+ if (Cand1.Function && Cand2.Function && Cand1.Function->hasPrototype() &&
+ Cand2.Function->hasPrototype()) {
+ auto *PT1 = cast<FunctionProtoType>(Cand1.Function->getFunctionType());
+ auto *PT2 = cast<FunctionProtoType>(Cand2.Function->getFunctionType());
+ if (PT1->getNumParams() == PT2->getNumParams() &&
+ PT1->isVariadic() == PT2->isVariadic() &&
+ S.FunctionParamTypesAreEqual(PT1, PT2, nullptr,
+ Cand1.isReversed() ^ Cand2.isReversed()))
+ return true;
+ }
+ return false;
+}
+
/// isBetterOverloadCandidate - Determines whether the first overload
/// candidate is a better candidate than the second (C++ 13.3.3p1).
bool clang::isBetterOverloadCandidate(
@@ -9815,34 +9847,28 @@
isa<CXXConversionDecl>(Cand1.Function) ? TPOC_Conversion
: TPOC_Call,
Cand1.ExplicitCallArguments, Cand2.ExplicitCallArguments,
- Cand1.isReversed() ^ Cand2.isReversed()))
+ Cand1.isReversed() ^ Cand2.isReversed(),
+ canCompareFunctionConstraints(S, Cand1, Cand2)))
return BetterTemplate == Cand1.Function->getPrimaryTemplate();
}
// -â F1 and F2 are non-template functions with the same
// parameter-type-lists, and F1 is more constrained than F2 [...],
- if (Cand1.Function && Cand2.Function && !Cand1IsSpecialization &&
- !Cand2IsSpecialization && Cand1.Function->hasPrototype() &&
- Cand2.Function->hasPrototype()) {
- auto *PT1 = cast<FunctionProtoType>(Cand1.Function->getFunctionType());
- auto *PT2 = cast<FunctionProtoType>(Cand2.Function->getFunctionType());
- if (PT1->getNumParams() == PT2->getNumParams() &&
- PT1->isVariadic() == PT2->isVariadic() &&
- S.FunctionParamTypesAreEqual(PT1, PT2)) {
- Expr *RC1 = Cand1.Function->getTrailingRequiresClause();
- Expr *RC2 = Cand2.Function->getTrailingRequiresClause();
- if (RC1 && RC2) {
- bool AtLeastAsConstrained1, AtLeastAsConstrained2;
- if (S.IsAtLeastAsConstrained(Cand1.Function, {RC1}, Cand2.Function,
- {RC2}, AtLeastAsConstrained1) ||
- S.IsAtLeastAsConstrained(Cand2.Function, {RC2}, Cand1.Function,
- {RC1}, AtLeastAsConstrained2))
- return false;
- if (AtLeastAsConstrained1 != AtLeastAsConstrained2)
- return AtLeastAsConstrained1;
- } else if (RC1 || RC2) {
- return RC1 != nullptr;
- }
+ if (!Cand1IsSpecialization && !Cand2IsSpecialization &&
+ canCompareFunctionConstraints(S, Cand1, Cand2)) {
+ Expr *RC1 = Cand1.Function->getTrailingRequiresClause();
+ Expr *RC2 = Cand2.Function->getTrailingRequiresClause();
+ if (RC1 && RC2) {
+ bool AtLeastAsConstrained1, AtLeastAsConstrained2;
+ if (S.IsAtLeastAsConstrained(Cand1.Function, {RC1}, Cand2.Function, {RC2},
+ AtLeastAsConstrained1) ||
+ S.IsAtLeastAsConstrained(Cand2.Function, {RC2}, Cand1.Function, {RC1},
+ AtLeastAsConstrained2))
+ return false;
+ if (AtLeastAsConstrained1 != AtLeastAsConstrained2)
+ return AtLeastAsConstrained1;
+ } else if (RC1 || RC2) {
+ return RC1 != nullptr;
}
}
Index: clang/include/clang/Sema/Sema.h
===================================================================
--- clang/include/clang/Sema/Sema.h
+++ clang/include/clang/Sema/Sema.h
@@ -3580,7 +3580,8 @@
QualType& ConvertedType);
bool FunctionParamTypesAreEqual(const FunctionProtoType *OldType,
const FunctionProtoType *NewType,
- unsigned *ArgPos = nullptr);
+ unsigned *ArgPos = nullptr,
+ bool Reversed = false);
void HandleFunctionTypeMismatch(PartialDiagnostic &PDiag,
QualType FromType, QualType ToType);
@@ -8749,7 +8750,8 @@
FunctionTemplateDecl *getMoreSpecializedTemplate(
FunctionTemplateDecl *FT1, FunctionTemplateDecl *FT2, SourceLocation Loc,
TemplatePartialOrderingContext TPOC, unsigned NumCallArguments1,
- unsigned NumCallArguments2, bool Reversed = false);
+ unsigned NumCallArguments2, bool Reversed = false,
+ bool AllowOrderingByConstraints = true);
UnresolvedSetIterator
getMostSpecialized(UnresolvedSetIterator SBegin, UnresolvedSetIterator SEnd,
TemplateSpecCandidateSet &FailedCandidates,
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -123,6 +123,11 @@
a lambda expression that shares the name of a variable in a containing
if/while/for/switch init statement as a redeclaration.
This fixes `Issue 54913 <https://github.com/llvm/llvm-project/issues/54913>`_.
+- Overload resolution for constrained function templates could use the partial
+ order of constraints to select an overload, even if the parameter types of
+ the functions were different. It now diagnoses this case correctly as an
+ ambiguous call and an error. Fixes
+ `Issue 53640 <https://github.com/llvm/llvm-project/issues/53640>`_.
Improvements to Clang's diagnostics
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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