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Unlike other types, when lambdas are instanciated,
they are recreated from scratch.
When an unevaluated lambdas appear in the type of a function,
parameter it is instanciated in the wrong declaration context,
as parameters are transformed before the function.
To support lambda in function parameters, we try to
compute whether they are dependant without looking at the
declaration context.
This is a short term stopgap solution to avoid clang
iceing. A better fix might be to inject some kind of
transparent declaration with correctly computed dependency
for function parameters, variable templates, etc.
Fixes https://github.com/llvm/llvm-project/issues/50376
Fixes https://github.com/llvm/llvm-project/issues/51414
Fixes https://github.com/llvm/llvm-project/issues/51416
Fixes https://github.com/llvm/llvm-project/issues/51641
Fixes https://github.com/llvm/llvm-project/issues/54296
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D121532
Files:
clang/include/clang/AST/DeclCXX.h
clang/include/clang/Sema/Sema.h
clang/lib/AST/ASTImporter.cpp
clang/lib/AST/DeclBase.cpp
clang/lib/AST/DeclCXX.cpp
clang/lib/Sema/SemaLambda.cpp
clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
clang/lib/Sema/TreeTransform.h
clang/lib/Serialization/ASTReaderDecl.cpp
clang/lib/Serialization/ASTWriter.cpp
clang/test/SemaCXX/lambda-unevaluated.cpp
Index: clang/test/SemaCXX/lambda-unevaluated.cpp
===================================================================
--- clang/test/SemaCXX/lambda-unevaluated.cpp
+++ clang/test/SemaCXX/lambda-unevaluated.cpp
@@ -30,6 +30,27 @@
auto e = g(0); // expected-error{{no matching function for call}}
// expected-note@-2 {{substitution failure}}
+template <typename T>
+auto foo(decltype([] {
+ return [] { return T(); }();
+})) {}
+
+void test() {
+ foo<int>({});
+}
+
+template <typename T>
+struct C {
+ template <typename U>
+ auto foo(decltype([] {
+ return [] { return T(); }();
+ })) {}
+};
+
+void test2() {
+ C<int>{}.foo<long>({});
+}
+
namespace PR52073 {
// OK, these are distinct functions not redefinitions.
template<typename> void f(decltype([]{})) {} // expected-note {{candidate}}
@@ -40,6 +61,62 @@
template<int N> void g(const char (*)[([]{ return N; })()]) {} // expected-note {{candidate}}
template<int N> void g(const char (*)[([]{ return N; })()]) {} // expected-note {{candidate}}
// FIXME: We instantiate the lambdas into the context of the function template,
-// so we think they're dependent and can't evaluate a call to them.
+// so we think they're dependent and can't evaluate a call to them.
void use_g() { g<6>(&"hello"); } // expected-error {{no matching function}}
}
+
+namespace GH51416 {
+
+template <class T>
+struct A {
+ void spam(decltype([] {}));
+};
+
+template <class T>
+void A<T>::spam(decltype([] {})) // expected-error{{out-of-line definition of 'spam' does not match}}
+{}
+
+struct B {
+ template <class T>
+ void spam(decltype([] {}));
+};
+
+template <class T>
+void B::spam(decltype([] {})) {} // expected-error{{out-of-line definition of 'spam' does not match}}
+
+} // namespace GH51416
+
+namespace GH50376 {
+
+template <typename T, typename Fn>
+struct foo_t { // expected-note 2{{candidate constructor}}
+ foo_t(T ptr) {} // expected-note{{candidate constructor}}
+};
+
+template <typename T>
+using alias = foo_t<T, decltype([](int) { return 0; })>;
+
+template <typename T>
+auto fun(T const &t) -> alias<T> {
+ return alias<T>{t}; // expected-error{{no viable conversion from returned value of type 'alias<...>'}}
+}
+
+void f() {
+ int i;
+ auto const error = fun(i); // expected-note{{in instantiation}}
+}
+
+} // namespace GH50376
+
+namespace GH51414 {
+template <class T> void spam(decltype([] {}) (*s)[sizeof(T)] = nullptr) {}
+void foo() {
+ spam<int>();
+}
+} // namespace GH51414
+
+namespace GH51641 {
+template <class T>
+void foo(decltype(+[](T) {}) lambda, T param);
+static_assert(!__is_same(decltype(foo<int>), void));
+} // namespace GH51641
Index: clang/lib/Serialization/ASTWriter.cpp
===================================================================
--- clang/lib/Serialization/ASTWriter.cpp
+++ clang/lib/Serialization/ASTWriter.cpp
@@ -5727,7 +5727,7 @@
// Add lambda-specific data.
if (Data.IsLambda) {
auto &Lambda = D->getLambdaData();
- Record->push_back(Lambda.Dependent);
+ Record->push_back(Lambda.DependencyKind);
Record->push_back(Lambda.IsGenericLambda);
Record->push_back(Lambda.CaptureDefault);
Record->push_back(Lambda.NumCaptures);
Index: clang/lib/Serialization/ASTReaderDecl.cpp
===================================================================
--- clang/lib/Serialization/ASTReaderDecl.cpp
+++ clang/lib/Serialization/ASTReaderDecl.cpp
@@ -1801,7 +1801,7 @@
using Capture = LambdaCapture;
auto &Lambda = static_cast<CXXRecordDecl::LambdaDefinitionData &>(Data);
- Lambda.Dependent = Record.readInt();
+ Lambda.DependencyKind = Record.readInt();
Lambda.IsGenericLambda = Record.readInt();
Lambda.CaptureDefault = Record.readInt();
Lambda.NumCaptures = Record.readInt();
@@ -1917,8 +1917,8 @@
// allocate the appropriate DefinitionData structure.
bool IsLambda = Record.readInt();
if (IsLambda)
- DD = new (C) CXXRecordDecl::LambdaDefinitionData(D, nullptr, false, false,
- LCD_None);
+ DD = new (C) CXXRecordDecl::LambdaDefinitionData(
+ D, nullptr, CXXRecordDecl::LDKUnknown, false, LCD_None);
else
DD = new (C) struct CXXRecordDecl::DefinitionData(D);
Index: clang/lib/Sema/TreeTransform.h
===================================================================
--- clang/lib/Sema/TreeTransform.h
+++ clang/lib/Sema/TreeTransform.h
@@ -12927,15 +12927,26 @@
NewTrailingRequiresClause = getDerived().TransformExpr(TRC);
// Create the local class that will describe the lambda.
- // FIXME: KnownDependent below is wrong when substituting inside a templated
- // context that isn't a DeclContext (such as a variable template).
+
+ // FIXME: DependencyKind below is wrong when substituting inside a templated
+ // context that isn't a DeclContext (such as a variable template), or when
+ // substituting an unevaluated lambda inside of a function's parameter's type
+ // - as parameter type are not instanciated from within a function's DC. We
+ // use isUnevaluatedContext() to distinguish the function parameter case.
+ CXXRecordDecl::LambdaDependencyKind DependencyKind =
+ CXXRecordDecl::LDKUnknown;
+ if (getSema().isUnevaluatedContext() &&
+ (getSema().CurContext->isFileContext() ||
+ !getSema().CurContext->getParent()->isDependentContext()))
+ DependencyKind = CXXRecordDecl::LDKNeverDependent;
+
CXXRecordDecl *OldClass = E->getLambdaClass();
- CXXRecordDecl *Class
- = getSema().createLambdaClosureType(E->getIntroducerRange(),
- NewCallOpTSI,
- /*KnownDependent=*/false,
- E->getCaptureDefault());
- getDerived().transformedLocalDecl(OldClass, {Class});
+ CXXRecordDecl *Class =
+ getSema().createLambdaClosureType(E->getIntroducerRange(), NewCallOpTSI,
+ DependencyKind, E->getCaptureDefault());
+
+ if (OldClass->isDependentContext())
+ getDerived().transformedLocalDecl(OldClass, {Class});
Optional<std::tuple<bool, unsigned, unsigned, Decl *>> Mangling;
if (getDerived().ReplacingOriginal())
@@ -12954,8 +12965,10 @@
LSI->CallOperator = NewCallOperator;
- getDerived().transformAttrs(E->getCallOperator(), NewCallOperator);
- getDerived().transformedLocalDecl(E->getCallOperator(), {NewCallOperator});
+ if (E->getCallOperator()->isDependentContext()) {
+ getDerived().transformAttrs(E->getCallOperator(), NewCallOperator);
+ getDerived().transformedLocalDecl(E->getCallOperator(), {NewCallOperator});
+ }
// Number the lambda for linkage purposes if necessary.
getSema().handleLambdaNumbering(Class, NewCallOperator, Mangling);
@@ -13024,7 +13037,8 @@
if (Invalid)
break;
- getDerived().transformedLocalDecl(OldVD, NewVDs);
+ if (OldVD->isTemplated())
+ getDerived().transformedLocalDecl(OldVD, NewVDs);
continue;
}
Index: clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
===================================================================
--- clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -1853,7 +1853,7 @@
if (D->isLambda())
Record = CXXRecordDecl::CreateLambda(
SemaRef.Context, Owner, D->getLambdaTypeInfo(), D->getLocation(),
- D->isDependentLambda(), D->isGenericLambda(),
+ D->getLambdaDependencyKind(), D->isGenericLambda(),
D->getLambdaCaptureDefault());
else
Record = CXXRecordDecl::Create(SemaRef.Context, D->getTagKind(), Owner,
Index: clang/lib/Sema/SemaLambda.cpp
===================================================================
--- clang/lib/Sema/SemaLambda.cpp
+++ clang/lib/Sema/SemaLambda.cpp
@@ -238,21 +238,19 @@
return LSI->GLTemplateParameterList;
}
-CXXRecordDecl *Sema::createLambdaClosureType(SourceRange IntroducerRange,
- TypeSourceInfo *Info,
- bool KnownDependent,
- LambdaCaptureDefault CaptureDefault) {
+CXXRecordDecl *
+Sema::createLambdaClosureType(SourceRange IntroducerRange, TypeSourceInfo *Info,
+ unsigned LambdaDependencyKind,
+ LambdaCaptureDefault CaptureDefault) {
DeclContext *DC = CurContext;
while (!(DC->isFunctionOrMethod() || DC->isRecord() || DC->isFileContext()))
DC = DC->getParent();
bool IsGenericLambda = getGenericLambdaTemplateParameterList(getCurLambda(),
*this);
// Start constructing the lambda class.
- CXXRecordDecl *Class = CXXRecordDecl::CreateLambda(Context, DC, Info,
- IntroducerRange.getBegin(),
- KnownDependent,
- IsGenericLambda,
- CaptureDefault);
+ CXXRecordDecl *Class = CXXRecordDecl::CreateLambda(
+ Context, DC, Info, IntroducerRange.getBegin(), LambdaDependencyKind,
+ IsGenericLambda, CaptureDefault);
DC->addDecl(Class);
return Class;
Index: clang/lib/AST/DeclCXX.cpp
===================================================================
--- clang/lib/AST/DeclCXX.cpp
+++ clang/lib/AST/DeclCXX.cpp
@@ -146,16 +146,16 @@
CXXRecordDecl *
CXXRecordDecl::CreateLambda(const ASTContext &C, DeclContext *DC,
TypeSourceInfo *Info, SourceLocation Loc,
- bool Dependent, bool IsGeneric,
+ unsigned DependencyKind, bool IsGeneric,
LambdaCaptureDefault CaptureDefault) {
auto *R = new (C, DC) CXXRecordDecl(CXXRecord, TTK_Class, C, DC, Loc, Loc,
nullptr, nullptr);
R->setBeingDefined(true);
- R->DefinitionData =
- new (C) struct LambdaDefinitionData(R, Info, Dependent, IsGeneric,
- CaptureDefault);
+ R->DefinitionData = new (C) struct LambdaDefinitionData(
+ R, Info, DependencyKind, IsGeneric, CaptureDefault);
R->setMayHaveOutOfDateDef(false);
R->setImplicit(true);
+
C.getTypeDeclType(R, /*PrevDecl=*/nullptr);
return R;
}
Index: clang/lib/AST/DeclBase.cpp
===================================================================
--- clang/lib/AST/DeclBase.cpp
+++ clang/lib/AST/DeclBase.cpp
@@ -1161,6 +1161,8 @@
if (Record->isDependentLambda())
return true;
+ if (Record->isNeverDependentLambda())
+ return false;
}
if (const auto *Function = dyn_cast<FunctionDecl>(this)) {
Index: clang/lib/AST/ASTImporter.cpp
===================================================================
--- clang/lib/AST/ASTImporter.cpp
+++ clang/lib/AST/ASTImporter.cpp
@@ -2874,7 +2874,7 @@
return TInfoOrErr.takeError();
if (GetImportedOrCreateSpecialDecl(
D2CXX, CXXRecordDecl::CreateLambda, D, Importer.getToContext(),
- DC, *TInfoOrErr, Loc, DCXX->isDependentLambda(),
+ DC, *TInfoOrErr, Loc, DCXX->getLambdaDependencyKind(),
DCXX->isGenericLambda(), DCXX->getLambdaCaptureDefault()))
return D2CXX;
ExpectedDecl CDeclOrErr = import(DCXX->getLambdaContextDecl());
Index: clang/include/clang/Sema/Sema.h
===================================================================
--- clang/include/clang/Sema/Sema.h
+++ clang/include/clang/Sema/Sema.h
@@ -6767,7 +6767,7 @@
/// Create a new lambda closure type.
CXXRecordDecl *createLambdaClosureType(SourceRange IntroducerRange,
TypeSourceInfo *Info,
- bool KnownDependent,
+ unsigned LambdaDependencyKind,
LambdaCaptureDefault CaptureDefault);
/// Start the definition of a lambda expression.
Index: clang/include/clang/AST/DeclCXX.h
===================================================================
--- clang/include/clang/AST/DeclCXX.h
+++ clang/include/clang/AST/DeclCXX.h
@@ -275,6 +275,14 @@
SMF_All = 0x3f
};
+public:
+ enum LambdaDependencyKind {
+ LDKUnknown = 0,
+ LDKAlwaysDependent,
+ LDKNeverDependent,
+ };
+
+private:
struct DefinitionData {
#define FIELD(Name, Width, Merge) \
unsigned Name : Width;
@@ -374,7 +382,7 @@
/// lambda will have been created with the enclosing context as its
/// declaration context, rather than function. This is an unfortunate
/// artifact of having to parse the default arguments before.
- unsigned Dependent : 1;
+ unsigned DependencyKind : 2;
/// Whether this lambda is a generic lambda.
unsigned IsGenericLambda : 1;
@@ -408,9 +416,9 @@
/// The type of the call method.
TypeSourceInfo *MethodTyInfo;
- LambdaDefinitionData(CXXRecordDecl *D, TypeSourceInfo *Info, bool Dependent,
+ LambdaDefinitionData(CXXRecordDecl *D, TypeSourceInfo *Info, unsigned DK,
bool IsGeneric, LambdaCaptureDefault CaptureDefault)
- : DefinitionData(D), Dependent(Dependent), IsGenericLambda(IsGeneric),
+ : DefinitionData(D), DependencyKind(DK), IsGenericLambda(IsGeneric),
CaptureDefault(CaptureDefault), NumCaptures(0),
NumExplicitCaptures(0), HasKnownInternalLinkage(0), ManglingNumber(0),
MethodTyInfo(Info) {
@@ -547,7 +555,7 @@
bool DelayTypeCreation = false);
static CXXRecordDecl *CreateLambda(const ASTContext &C, DeclContext *DC,
TypeSourceInfo *Info, SourceLocation Loc,
- bool DependentLambda, bool IsGeneric,
+ unsigned DependencyKind, bool IsGeneric,
LambdaCaptureDefault CaptureDefault);
static CXXRecordDecl *CreateDeserialized(const ASTContext &C, unsigned ID);
@@ -1774,7 +1782,17 @@
/// function declaration itself is dependent. This flag indicates when we
/// know that the lambda is dependent despite that.
bool isDependentLambda() const {
- return isLambda() && getLambdaData().Dependent;
+ return isLambda() && getLambdaData().DependencyKind == LDKAlwaysDependent;
+ }
+
+ bool isNeverDependentLambda() const {
+ return isLambda() && getLambdaData().DependencyKind == LDKNeverDependent;
+ }
+
+ unsigned getLambdaDependencyKind() const {
+ if (!isLambda())
+ return LDKUnknown;
+ return getLambdaData().DependencyKind;
}
TypeSourceInfo *getLambdaTypeInfo() const {
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