[Concepts] Constraint Enforcement & Diagnostics
Part of the C++20 concepts implementation effort.
- Associated constraints (requires clauses, currently) are now enforced when instantiating/specializing templates and when considering partial specializations and function overloads.
- Elaborated diagnostics give helpful insight as to why the constraints were not satisfied.
Phabricator: D41569
Re-commit, after fixing some memory bugs.
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 7dd1e90..6998955 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -3213,8 +3213,7 @@
TemplateDecl *Template = Name.getAsTemplateDecl();
if (!Template || isa<FunctionTemplateDecl>(Template) ||
- isa<VarTemplateDecl>(Template) ||
- isa<ConceptDecl>(Template)) {
+ isa<VarTemplateDecl>(Template) || isa<ConceptDecl>(Template)) {
// We might have a substituted template template parameter pack. If so,
// build a template specialization type for it.
if (Name.getAsSubstTemplateTemplateParmPack())
@@ -3230,7 +3229,8 @@
// template.
SmallVector<TemplateArgument, 4> Converted;
if (CheckTemplateArgumentList(Template, TemplateLoc, TemplateArgs,
- false, Converted))
+ false, Converted,
+ /*UpdateArgsWithConversion=*/true))
return QualType();
QualType CanonType;
@@ -3238,6 +3238,7 @@
bool InstantiationDependent = false;
if (TypeAliasTemplateDecl *AliasTemplate =
dyn_cast<TypeAliasTemplateDecl>(Template)) {
+
// Find the canonical type for this type alias template specialization.
TypeAliasDecl *Pattern = AliasTemplate->getTemplatedDecl();
if (Pattern->isInvalidDecl())
@@ -3875,7 +3876,8 @@
// template.
SmallVector<TemplateArgument, 4> Converted;
if (CheckTemplateArgumentList(VarTemplate, TemplateNameLoc, TemplateArgs,
- false, Converted))
+ false, Converted,
+ /*UpdateArgsWithConversion=*/true))
return true;
// Find the variable template (partial) specialization declaration that
@@ -4046,7 +4048,7 @@
if (CheckTemplateArgumentList(
Template, TemplateNameLoc,
const_cast<TemplateArgumentListInfo &>(TemplateArgs), false,
- Converted))
+ Converted, /*UpdateArgsWithConversion=*/true))
return true;
// Find the variable template specialization declaration that
@@ -4237,7 +4239,7 @@
/*UpdateArgsWithConversion=*/false))
return ExprError();
- Optional<bool> IsSatisfied;
+ ConstraintSatisfaction Satisfaction;
bool AreArgsDependent = false;
for (TemplateArgument &Arg : Converted) {
if (Arg.isDependent()) {
@@ -4245,25 +4247,21 @@
break;
}
}
- if (!AreArgsDependent) {
- InstantiatingTemplate Inst(*this, ConceptNameLoc,
- InstantiatingTemplate::ConstraintsCheck{}, NamedConcept, Converted,
- SourceRange(SS.isSet() ? SS.getBeginLoc() : ConceptNameLoc,
- TemplateArgs->getRAngleLoc()));
- MultiLevelTemplateArgumentList MLTAL;
- MLTAL.addOuterTemplateArguments(Converted);
- bool Satisfied;
- if (CalculateConstraintSatisfaction(NamedConcept, MLTAL,
- NamedConcept->getConstraintExpr(),
- Satisfied))
+ if (!AreArgsDependent &&
+ CheckConstraintSatisfaction(NamedConcept,
+ {NamedConcept->getConstraintExpr()},
+ Converted,
+ SourceRange(SS.isSet() ? SS.getBeginLoc() :
+ ConceptNameLoc,
+ TemplateArgs->getRAngleLoc()),
+ Satisfaction))
return ExprError();
- IsSatisfied = Satisfied;
- }
+
return ConceptSpecializationExpr::Create(Context,
SS.isSet() ? SS.getWithLocInContext(Context) : NestedNameSpecifierLoc{},
TemplateKWLoc, ConceptNameLoc, FoundDecl, NamedConcept,
ASTTemplateArgumentListInfo::Create(Context, *TemplateArgs), Converted,
- IsSatisfied);
+ AreArgsDependent ? nullptr : &Satisfaction);
}
ExprResult Sema::BuildTemplateIdExpr(const CXXScopeSpec &SS,
@@ -5209,7 +5207,11 @@
TemplateDecl *Template, SourceLocation TemplateLoc,
TemplateArgumentListInfo &TemplateArgs, bool PartialTemplateArgs,
SmallVectorImpl<TemplateArgument> &Converted,
- bool UpdateArgsWithConversions) {
+ bool UpdateArgsWithConversions, bool *ConstraintsNotSatisfied) {
+
+ if (ConstraintsNotSatisfied)
+ *ConstraintsNotSatisfied = false;
+
// Make a copy of the template arguments for processing. Only make the
// changes at the end when successful in matching the arguments to the
// template.
@@ -5324,7 +5326,6 @@
if ((*Param)->isTemplateParameterPack() && !ArgumentPack.empty())
Converted.push_back(
TemplateArgument::CreatePackCopy(Context, ArgumentPack));
-
return false;
}
@@ -5463,6 +5464,15 @@
if (UpdateArgsWithConversions)
TemplateArgs = std::move(NewArgs);
+ if (!PartialTemplateArgs &&
+ EnsureTemplateArgumentListConstraints(
+ Template, Converted, SourceRange(TemplateLoc,
+ TemplateArgs.getRAngleLoc()))) {
+ if (ConstraintsNotSatisfied)
+ *ConstraintsNotSatisfied = true;
+ return true;
+ }
+
return false;
}
@@ -7776,7 +7786,8 @@
// template.
SmallVector<TemplateArgument, 4> Converted;
if (CheckTemplateArgumentList(ClassTemplate, TemplateNameLoc,
- TemplateArgs, false, Converted))
+ TemplateArgs, false, Converted,
+ /*UpdateArgsWithConversion=*/true))
return true;
// Find the class template (partial) specialization declaration that
@@ -9022,7 +9033,8 @@
// template.
SmallVector<TemplateArgument, 4> Converted;
if (CheckTemplateArgumentList(ClassTemplate, TemplateNameLoc,
- TemplateArgs, false, Converted))
+ TemplateArgs, false, Converted,
+ /*UpdateArgsWithConversion=*/true))
return true;
// Find the class template specialization declaration that