[clang] 128b3b6 - [Clang] Defer the instantiation of explicit-specifier until constraint checking completes (#70548)
via cfe-commits
cfe-commits at lists.llvm.org
Wed Nov 1 06:45:52 PDT 2023
Author: 刘雨培
Date: 2023-11-01T06:45:48-07:00
New Revision: 128b3b61fe6768c724975fd1df2be0abec848cf6
URL: https://github.com/llvm/llvm-project/commit/128b3b61fe6768c724975fd1df2be0abec848cf6
DIFF: https://github.com/llvm/llvm-project/commit/128b3b61fe6768c724975fd1df2be0abec848cf6.diff
LOG: [Clang] Defer the instantiation of explicit-specifier until constraint checking completes (#70548)
Modifications:
- Skip the instantiation of the explicit-specifier during Decl
substitution if we are deducing template arguments and the
explicit-specifier is value dependent.
- Instantiate the explicit-specifier after the constraint checking
completes.
- Make `instantiateExplicitSpecifier` a member function in order to
instantiate the explicit-specifier in different stages.
This PR doesn’t defer the instantiation of the explicit specifier for
deduction guides, because I’m not familiar with deduction guides yet.
I’ll dig into it after this PR.
According to my local test, GCC 13 tuple works with this PR.
Fixes #59827.
---------
Co-authored-by: Erich Keane <ekeane at nvidia.com>
Added:
clang/test/SemaCXX/cxx2a-explicit-bool-deferred.cpp
Modified:
clang/docs/ReleaseNotes.rst
clang/include/clang/Sema/Sema.h
clang/lib/Sema/SemaTemplateDeduction.cpp
clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
Removed:
################################################################################
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 103dcbeb79624d9..3198d6bfe75a2e8 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -682,6 +682,10 @@ Bug Fixes to C++ Support
Fixes:
(`#68769 <https://github.com/llvm/llvm-project/issues/68769>`_)
+- Clang now defers the instantiation of explicit specifier until constraint checking
+ completes (except deduction guides). Fixes:
+ (`#59827 <https://github.com/llvm/llvm-project/issues/59827>`_)
+
Bug Fixes to AST Handling
^^^^^^^^^^^^^^^^^^^^^^^^^
- Fixed an import failure of recursive friend class template.
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 91a4211a5cf5cce..daed24be0a86d11 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -10430,6 +10430,9 @@ class Sema final {
const CXXConstructorDecl *Tmpl,
const MultiLevelTemplateArgumentList &TemplateArgs);
+ ExplicitSpecifier instantiateExplicitSpecifier(
+ const MultiLevelTemplateArgumentList &TemplateArgs, ExplicitSpecifier ES);
+
NamedDecl *FindInstantiatedDecl(SourceLocation Loc, NamedDecl *D,
const MultiLevelTemplateArgumentList &TemplateArgs,
bool FindingInstantiatedContext = false);
diff --git a/clang/lib/Sema/SemaTemplateDeduction.cpp b/clang/lib/Sema/SemaTemplateDeduction.cpp
index 0b3f0247ea3bee3..699e0985e595b65 100644
--- a/clang/lib/Sema/SemaTemplateDeduction.cpp
+++ b/clang/lib/Sema/SemaTemplateDeduction.cpp
@@ -3553,6 +3553,48 @@ static unsigned getPackIndexForParam(Sema &S,
llvm_unreachable("parameter index would not be produced from template");
}
+// if `Specialization` is a `CXXConstructorDecl` or `CXXConversionDecl`,
+// we'll try to instantiate and update its explicit specifier after constraint
+// checking.
+static Sema::TemplateDeductionResult instantiateExplicitSpecifierDeferred(
+ Sema &S, FunctionDecl *Specialization,
+ const MultiLevelTemplateArgumentList &SubstArgs,
+ TemplateDeductionInfo &Info, FunctionTemplateDecl *FunctionTemplate,
+ ArrayRef<TemplateArgument> DeducedArgs) {
+ auto GetExplicitSpecifier = [](FunctionDecl *D) {
+ return isa<CXXConstructorDecl>(D)
+ ? cast<CXXConstructorDecl>(D)->getExplicitSpecifier()
+ : cast<CXXConversionDecl>(D)->getExplicitSpecifier();
+ };
+ auto SetExplicitSpecifier = [](FunctionDecl *D, ExplicitSpecifier ES) {
+ isa<CXXConstructorDecl>(D)
+ ? cast<CXXConstructorDecl>(D)->setExplicitSpecifier(ES)
+ : cast<CXXConversionDecl>(D)->setExplicitSpecifier(ES);
+ };
+
+ ExplicitSpecifier ES = GetExplicitSpecifier(Specialization);
+ Expr *ExplicitExpr = ES.getExpr();
+ if (!ExplicitExpr)
+ return Sema::TDK_Success;
+ if (!ExplicitExpr->isValueDependent())
+ return Sema::TDK_Success;
+
+ Sema::InstantiatingTemplate Inst(
+ S, Info.getLocation(), FunctionTemplate, DeducedArgs,
+ Sema::CodeSynthesisContext::DeducedTemplateArgumentSubstitution, Info);
+ if (Inst.isInvalid())
+ return Sema::TDK_InstantiationDepth;
+ Sema::SFINAETrap Trap(S);
+ const ExplicitSpecifier InstantiatedES =
+ S.instantiateExplicitSpecifier(SubstArgs, ES);
+ if (InstantiatedES.isInvalid() || Trap.hasErrorOccurred()) {
+ Specialization->setInvalidDecl(true);
+ return Sema::TDK_SubstitutionFailure;
+ }
+ SetExplicitSpecifier(Specialization, InstantiatedES);
+ return Sema::TDK_Success;
+}
+
/// Finish template argument deduction for a function template,
/// checking the deduced template arguments for completeness and forming
/// the function template specialization.
@@ -3682,6 +3724,17 @@ Sema::TemplateDeductionResult Sema::FinishTemplateArgumentDeduction(
}
}
+ // We skipped the instantiation of the explicit-specifier during the
+ // substitution of `FD` before. So, we try to instantiate it back if
+ // `Specialization` is either a constructor or a conversion function.
+ if (isa<CXXConstructorDecl, CXXConversionDecl>(Specialization)) {
+ if (TDK_Success != instantiateExplicitSpecifierDeferred(
+ *this, Specialization, SubstArgs, Info,
+ FunctionTemplate, DeducedArgs)) {
+ return TDK_SubstitutionFailure;
+ }
+ }
+
if (OriginalCallArgs) {
// C++ [temp.deduct.call]p4:
// In general, the deduction process attempts to find template argument
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 11d4c83dba77d96..8edcbf4709a2301 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -563,18 +563,16 @@ static void instantiateDependentAMDGPUFlatWorkGroupSizeAttr(
S.addAMDGPUFlatWorkGroupSizeAttr(New, Attr, MinExpr, MaxExpr);
}
-static ExplicitSpecifier
-instantiateExplicitSpecifier(Sema &S,
- const MultiLevelTemplateArgumentList &TemplateArgs,
- ExplicitSpecifier ES, FunctionDecl *New) {
+ExplicitSpecifier Sema::instantiateExplicitSpecifier(
+ const MultiLevelTemplateArgumentList &TemplateArgs, ExplicitSpecifier ES) {
if (!ES.getExpr())
return ES;
Expr *OldCond = ES.getExpr();
Expr *Cond = nullptr;
{
EnterExpressionEvaluationContext Unevaluated(
- S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
- ExprResult SubstResult = S.SubstExpr(OldCond, TemplateArgs);
+ *this, Sema::ExpressionEvaluationContext::ConstantEvaluated);
+ ExprResult SubstResult = SubstExpr(OldCond, TemplateArgs);
if (SubstResult.isInvalid()) {
return ExplicitSpecifier::Invalid();
}
@@ -582,7 +580,7 @@ instantiateExplicitSpecifier(Sema &S,
}
ExplicitSpecifier Result(Cond, ES.getKind());
if (!Cond->isTypeDependent())
- S.tryResolveExplicitSpecifier(Result);
+ tryResolveExplicitSpecifier(Result);
return Result;
}
@@ -2073,8 +2071,8 @@ Decl *TemplateDeclInstantiator::VisitFunctionDecl(
ExplicitSpecifier InstantiatedExplicitSpecifier;
if (auto *DGuide = dyn_cast<CXXDeductionGuideDecl>(D)) {
- InstantiatedExplicitSpecifier = instantiateExplicitSpecifier(
- SemaRef, TemplateArgs, DGuide->getExplicitSpecifier(), DGuide);
+ InstantiatedExplicitSpecifier = SemaRef.instantiateExplicitSpecifier(
+ TemplateArgs, DGuide->getExplicitSpecifier());
if (InstantiatedExplicitSpecifier.isInvalid())
return nullptr;
}
@@ -2453,11 +2451,25 @@ Decl *TemplateDeclInstantiator::VisitCXXMethodDecl(
}
}
- ExplicitSpecifier InstantiatedExplicitSpecifier =
- instantiateExplicitSpecifier(SemaRef, TemplateArgs,
- ExplicitSpecifier::getFromDecl(D), D);
- if (InstantiatedExplicitSpecifier.isInvalid())
- return nullptr;
+ auto InstantiatedExplicitSpecifier = ExplicitSpecifier::getFromDecl(D);
+ // deduction guides need this
+ const bool CouldInstantiate =
+ InstantiatedExplicitSpecifier.getExpr() == nullptr ||
+ !InstantiatedExplicitSpecifier.getExpr()->isValueDependent();
+
+ // Delay the instantiation of the explicit-specifier until after the
+ // constraints are checked during template argument deduction.
+ if (CouldInstantiate ||
+ SemaRef.CodeSynthesisContexts.back().Kind !=
+ Sema::CodeSynthesisContext::DeducedTemplateArgumentSubstitution) {
+ InstantiatedExplicitSpecifier = SemaRef.instantiateExplicitSpecifier(
+ TemplateArgs, InstantiatedExplicitSpecifier);
+
+ if (InstantiatedExplicitSpecifier.isInvalid())
+ return nullptr;
+ } else {
+ InstantiatedExplicitSpecifier.setKind(ExplicitSpecKind::Unresolved);
+ }
// Implicit destructors/constructors created for local classes in
// DeclareImplicit* (see SemaDeclCXX.cpp) might not have an associated TSI.
diff --git a/clang/test/SemaCXX/cxx2a-explicit-bool-deferred.cpp b/clang/test/SemaCXX/cxx2a-explicit-bool-deferred.cpp
new file mode 100644
index 000000000000000..4d667008f2e2763
--- /dev/null
+++ b/clang/test/SemaCXX/cxx2a-explicit-bool-deferred.cpp
@@ -0,0 +1,31 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++2a %s
+
+template <typename T1, typename T2> struct is_same {
+ static constexpr bool value = false;
+};
+
+template <typename T> struct is_same<T, T> {
+ static constexpr bool value = true;
+};
+
+template <class T, class U>
+concept SameHelper = is_same<T, U>::value;
+template <class T, class U>
+concept same_as = SameHelper<T, U> && SameHelper<U, T>;
+
+namespace deferred_instantiation {
+template <class X> constexpr X do_not_instantiate() { return nullptr; }
+
+struct T {
+ template <same_as<float> X> explicit(do_not_instantiate<X>()) T(X) {}
+
+ T(int) {}
+};
+
+T t(5);
+// expected-error at 17{{cannot initialize}}
+// expected-note at 20{{in instantiation of function template specialization}}
+// expected-note at 30{{while substituting deduced template arguments}}
+// expected-note at 30{{in instantiation of function template specialization}}
+T t2(5.0f);
+} // namespace deferred_instantiation
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