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[clang][ASTImporter] Update lookup table correctly at deduction guides. 

Declaration context of template parameters of a FunctionTemplateDecl
may be different for each one parameter if the template is a
deduction guide. This case is handled correctly after this change.

Reviewed By: martong

Differential Revision: https://reviews.llvm.org/D114418
This commit is contained in:
Balázs Kéri 2021-12-06 18:16:02 +01:00 committed by Gabor Marton
parent 73ee4e1cbd
commit 341a30a4ba
4 changed files with 170 additions and 15 deletions
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4
clang/include/clang/AST/ASTImporterLookupTable.h
View File

@ -75,6 +75,10 @@ public:
// The function should be called when the old context is definitely different
// from the new.
void update(NamedDecl *ND, DeclContext *OldDC);
// Same as 'update' but allow if 'ND' is not in the table or the old context
// is the same as the new.
// FIXME: The old redeclaration context is not handled.
void updateForced(NamedDecl *ND, DeclContext *OldDC);
using LookupResult = DeclList;
LookupResult lookup(DeclContext *DC, DeclarationName Name) const;
// Check if the `ND` is within the lookup table (with its current name) in

39
clang/lib/AST/ASTImporter.cpp
View File

@ -6066,20 +6066,24 @@ ASTNodeImporter::VisitFunctionTemplateDecl(FunctionTemplateDecl *D) {
if (Error Err = importInto(TemplatedFD, D->getTemplatedDecl()))
return std::move(Err);
// Template parameters of the ClassTemplateDecl and FunctionTemplateDecl are
// shared, if the FunctionTemplateDecl is a deduction guide for the class.
// At import the ClassTemplateDecl object is always created first (FIXME: is
// this really true?) because the dependency, then the FunctionTemplateDecl.
// The DeclContext of the template parameters is changed when the
// FunctionTemplateDecl is created, but was set already when the class
// template was created. So here it is not the TU (default value) any more.
// FIXME: The DeclContext of the parameters is now set finally to the
// CXXDeductionGuideDecl object that was imported later. This may not be the
// same that is in the original AST, specially if there are multiple deduction
// guides.
DeclContext *OldParamDC = nullptr;
if (Params->size() > 0)
OldParamDC = Params->getParam(0)->getDeclContext();
// At creation of the template the template parameters are "adopted"
// (DeclContext is changed). After this possible change the lookup table
// must be updated.
// At deduction guides the DeclContext of the template parameters may be
// different from what we would expect, it may be the class template, or a
// probably different CXXDeductionGuideDecl. This may come from the fact that
// the template parameter objects may be shared between deduction guides or
// the class template, and at creation of multiple FunctionTemplateDecl
// objects (for deduction guides) the same parameters are re-used. The
// "adoption" happens multiple times with different parent, even recursively
// for TemplateTemplateParmDecl. The same happens at import when the
// FunctionTemplateDecl objects are created, but in different order.
// In this way the DeclContext of these template parameters is not necessarily
// the same as in the "from" context.
SmallVector<DeclContext *, 2> OldParamDC;
OldParamDC.reserve(Params->size());
llvm::transform(*Params, std::back_inserter(OldParamDC),
[](NamedDecl *ND) { return ND->getDeclContext(); });
FunctionTemplateDecl *ToFunc;
if (GetImportedOrCreateDecl(ToFunc, D, Importer.getToContext(), DC, Loc, Name,
@ -6091,7 +6095,12 @@ ASTNodeImporter::VisitFunctionTemplateDecl(FunctionTemplateDecl *D) {
ToFunc->setAccess(D->getAccess());
ToFunc->setLexicalDeclContext(LexicalDC);
LexicalDC->addDeclInternal(ToFunc);
updateLookupTableForTemplateParameters(*Params, OldParamDC);
ASTImporterLookupTable *LT = Importer.SharedState->getLookupTable();
if (LT && !OldParamDC.empty()) {
for (unsigned int I = 0; I < OldParamDC.size(); ++I)
LT->updateForced(Params->getParam(I), OldParamDC[I]);
}
if (FoundByLookup) {
auto *Recent =

5
clang/lib/AST/ASTImporterLookupTable.cpp
View File

@ -140,6 +140,11 @@ void ASTImporterLookupTable::update(NamedDecl *ND, DeclContext *OldDC) {
add(ND);
}
void ASTImporterLookupTable::updateForced(NamedDecl *ND, DeclContext *OldDC) {
LookupTable[OldDC][ND->getDeclName()].remove(ND);
add(ND);
}
ASTImporterLookupTable::LookupResult
ASTImporterLookupTable::lookup(DeclContext *DC, DeclarationName Name) const {
auto DCI = LookupTable.find(DC->getPrimaryContext());

137
clang/unittests/AST/ASTImporterTest.cpp
View File

@ -7329,6 +7329,143 @@ TEST_P(ASTImporterOptionSpecificTestBase, ImportUsingShadowList) {
EXPECT_EQ(*ShadowI, ToUsingShadowF2);
}
AST_MATCHER_P(FunctionTemplateDecl, templateParameterCountIs, unsigned, Cnt) {
return Node.getTemplateParameters()->size() == Cnt;
}
TEST_P(ASTImporterOptionSpecificTestBase, ImportDeductionGuide) {
TranslationUnitDecl *FromTU = getTuDecl(
R"(
template<class> class A { };
template<class T> class B {
template<class T1, typename = A<T>> B(T1);
};
template<class T>
B(T, T) -> B<int>;
)",
Lang_CXX17);
// Get the implicit deduction guide for (non-default) constructor of 'B'.
auto *FromDGCtor = FirstDeclMatcher<FunctionTemplateDecl>().match(
FromTU, functionTemplateDecl(templateParameterCountIs(3)));
// Implicit deduction guide for copy constructor of 'B'.
auto *FromDGCopyCtor = FirstDeclMatcher<FunctionTemplateDecl>().match(
FromTU, functionTemplateDecl(templateParameterCountIs(1), isImplicit()));
// User defined deduction guide.
auto *FromDGOther = FirstDeclMatcher<CXXDeductionGuideDecl>().match(
FromTU, cxxDeductionGuideDecl(unless(isImplicit())));
TemplateParameterList *FromDGCtorTP = FromDGCtor->getTemplateParameters();
// Don't know why exactly but this is the DeclContext here.
EXPECT_EQ(FromDGCtorTP->getParam(0)->getDeclContext(),
FromDGCopyCtor->getTemplatedDecl());
EXPECT_EQ(FromDGCtorTP->getParam(1)->getDeclContext(),
FromDGCtor->getTemplatedDecl());
EXPECT_EQ(FromDGCtorTP->getParam(2)->getDeclContext(),
FromDGCtor->getTemplatedDecl());
EXPECT_EQ(
FromDGCopyCtor->getTemplateParameters()->getParam(0)->getDeclContext(),
FromDGCopyCtor->getTemplatedDecl());
EXPECT_EQ(FromDGOther->getDescribedTemplate()
->getTemplateParameters()
->getParam(0)
->getDeclContext(),
FromDGOther);
auto *ToDGCtor = Import(FromDGCtor, Lang_CXX17);
auto *ToDGCopyCtor = Import(FromDGCopyCtor, Lang_CXX17);
auto *ToDGOther = Import(FromDGOther, Lang_CXX17);
ASSERT_TRUE(ToDGCtor);
ASSERT_TRUE(ToDGCopyCtor);
ASSERT_TRUE(ToDGOther);
TemplateParameterList *ToDGCtorTP = ToDGCtor->getTemplateParameters();
EXPECT_EQ(ToDGCtorTP->getParam(0)->getDeclContext(),
ToDGCopyCtor->getTemplatedDecl());
EXPECT_EQ(ToDGCtorTP->getParam(1)->getDeclContext(),
ToDGCtor->getTemplatedDecl());
EXPECT_EQ(ToDGCtorTP->getParam(2)->getDeclContext(),
ToDGCtor->getTemplatedDecl());
EXPECT_EQ(
ToDGCopyCtor->getTemplateParameters()->getParam(0)->getDeclContext(),
ToDGCopyCtor->getTemplatedDecl());
EXPECT_EQ(ToDGOther->getDescribedTemplate()
->getTemplateParameters()
->getParam(0)
->getDeclContext(),
ToDGOther);
}
TEST_P(ASTImporterOptionSpecificTestBase, ImportDeductionGuideDifferentOrder) {
// This test demonstrates that the DeclContext of the imported object is
// dependent on the order of import. The test is an exact copy of the previous
// one except at the indicated locations.
TranslationUnitDecl *FromTU = getTuDecl(
R"(
template<class> class A { };
template<class T> class B {
template<class T1, typename = A<T>> B(T1);
};
template<class T>
B(T, T) -> B<int>;
)",
Lang_CXX17);
// Get the implicit deduction guide for (non-default) constructor of 'B'.
auto *FromDGCtor = FirstDeclMatcher<FunctionTemplateDecl>().match(
FromTU, functionTemplateDecl(templateParameterCountIs(3)));
// Implicit deduction guide for copy constructor of 'B'.
auto *FromDGCopyCtor = FirstDeclMatcher<FunctionTemplateDecl>().match(
FromTU, functionTemplateDecl(templateParameterCountIs(1), isImplicit()));
// User defined deduction guide.
auto *FromDGOther = FirstDeclMatcher<CXXDeductionGuideDecl>().match(
FromTU, cxxDeductionGuideDecl(unless(isImplicit())));
TemplateParameterList *FromDGCtorTP = FromDGCtor->getTemplateParameters();
// Don't know why exactly but this is the DeclContext here.
EXPECT_EQ(FromDGCtorTP->getParam(0)->getDeclContext(),
FromDGCopyCtor->getTemplatedDecl());
EXPECT_EQ(FromDGCtorTP->getParam(1)->getDeclContext(),
FromDGCtor->getTemplatedDecl());
EXPECT_EQ(FromDGCtorTP->getParam(2)->getDeclContext(),
FromDGCtor->getTemplatedDecl());
EXPECT_EQ(
FromDGCopyCtor->getTemplateParameters()->getParam(0)->getDeclContext(),
FromDGCopyCtor->getTemplatedDecl());
EXPECT_EQ(FromDGOther->getDescribedTemplate()
->getTemplateParameters()
->getParam(0)
->getDeclContext(),
FromDGOther);
// Here the import of 'ToDGCopyCtor' and 'ToDGCtor' is reversed relative to
// the previous test.
auto *ToDGCopyCtor = Import(FromDGCopyCtor, Lang_CXX17);
auto *ToDGCtor = Import(FromDGCtor, Lang_CXX17);
auto *ToDGOther = Import(FromDGOther, Lang_CXX17);
ASSERT_TRUE(ToDGCtor);
ASSERT_TRUE(ToDGCopyCtor);
ASSERT_TRUE(ToDGOther);
TemplateParameterList *ToDGCtorTP = ToDGCtor->getTemplateParameters();
// Next line: DeclContext is different relative to the previous test.
EXPECT_EQ(ToDGCtorTP->getParam(0)->getDeclContext(),
ToDGCtor->getTemplatedDecl());
EXPECT_EQ(ToDGCtorTP->getParam(1)->getDeclContext(),
ToDGCtor->getTemplatedDecl());
EXPECT_EQ(ToDGCtorTP->getParam(2)->getDeclContext(),
ToDGCtor->getTemplatedDecl());
// Next line: DeclContext is different relative to the previous test.
EXPECT_EQ(
ToDGCopyCtor->getTemplateParameters()->getParam(0)->getDeclContext(),
ToDGCtor->getTemplatedDecl());
EXPECT_EQ(ToDGOther->getDescribedTemplate()
->getTemplateParameters()
->getParam(0)
->getDeclContext(),
ToDGOther);
}
INSTANTIATE_TEST_SUITE_P(ParameterizedTests, ASTImporterLookupTableTest,
DefaultTestValuesForRunOptions);