================
@@ -2744,31 +2744,155 @@ bool hasDeclaredDeductionGuides(DeclarationName Name,
DeclContext *DC) {
return false;
}
+unsigned getTemplateDepth(NamedDecl *TemplateParam) {
+ if (auto *TTP = dyn_cast<TemplateTypeParmDecl>(TemplateParam))
+ return TTP->getDepth();
+ if (auto *TTP = dyn_cast<TemplateTemplateParmDecl>(TemplateParam))
+ return TTP->getDepth();
+ if (auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(TemplateParam))
+ return NTTP->getDepth();
+ llvm_unreachable("Unhandled template parameter types");
+}
+
NamedDecl *transformTemplateParameter(Sema &SemaRef, DeclContext *DC,
NamedDecl *TemplateParam,
MultiLevelTemplateArgumentList &Args,
- unsigned NewIndex) {
+ unsigned NewIndex, unsigned NewDepth) {
if (auto *TTP = dyn_cast<TemplateTypeParmDecl>(TemplateParam))
- return transformTemplateTypeParam(SemaRef, DC, TTP, Args, TTP->getDepth(),
+ return transformTemplateTypeParam(SemaRef, DC, TTP, Args, NewDepth,
NewIndex);
if (auto *TTP = dyn_cast<TemplateTemplateParmDecl>(TemplateParam))
return transformTemplateParam(SemaRef, DC, TTP, Args, NewIndex,
- TTP->getDepth());
+ NewDepth);
if (auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(TemplateParam))
return transformTemplateParam(SemaRef, DC, NTTP, Args, NewIndex,
- NTTP->getDepth());
+ NewDepth);
llvm_unreachable("Unhandled template parameter types");
}
-Expr *transformRequireClause(Sema &SemaRef, FunctionTemplateDecl *FTD,
- llvm::ArrayRef<TemplateArgument> TransformedArgs)
{
- Expr *RC = FTD->getTemplateParameters()->getRequiresClause();
+// Transform the require-clause of F if any.
+// The return result is expected to be the require-clause for the synthesized
+// alias deduction guide.
+Expr *transformRequireClause(
+ Sema &SemaRef, FunctionTemplateDecl *F,
+ TypeAliasTemplateDecl *AliasTemplate,
+ ArrayRef<DeducedTemplateArgument> DeduceResults) {
+ Expr *RC = F->getTemplateParameters()->getRequiresClause();
if (!RC)
return nullptr;
+
+ auto &Context = SemaRef.Context;
+ LocalInstantiationScope Scope(SemaRef);
+
+ // In the clang AST, constraint nodes are not instantiated at all unless they
+ // are being evaluated. This means that occurrences of template parameters
+ // in the require-clause expr have subtle differences compared to occurrences
+ // in other places, such as function parameters. When transforming the
+ // require-clause, we must respect these differences, particularly regarding
+ // the 'depth' information:
+ // 1) In the transformed require-clause, occurrences of template parameters
+ // must use the "uninstantiated" depth;
+ // 2) When substituting on the require-clause expr of the underlying
+ // deduction guide, we must use the entire set of template argument lists.
+ //
+ // It's important to note that we're performing this transformation on an
+ // *instantiated* AliasTemplate.
+
+ // For 1), if the alias template is nested within a class template, we
+ // calcualte the 'uninstantiated' depth by adding the substitution level
back.
+ unsigned AdjustDepth = 0;
+ if (auto *PrimaryTemplate =
AliasTemplate->getInstantiatedFromMemberTemplate())
+ AdjustDepth = PrimaryTemplate->getTemplateDepth();
+
+ // We rebuild all template parameters with the uninstantiated depth, and
+ // build template arguments refer to them.
+ SmallVector<TemplateArgument> AdjustedAliasTemplateArgs;
+
+ for (auto *TP : *AliasTemplate->getTemplateParameters()) {
+ // Rebuild any internal references to earlier parameters and reindex
+ // as we go.
+ MultiLevelTemplateArgumentList Args;
+ Args.setKind(TemplateSubstitutionKind::Rewrite);
+ Args.addOuterTemplateArguments(AdjustedAliasTemplateArgs);
+ NamedDecl *NewParam = transformTemplateParameter(
+ SemaRef, AliasTemplate->getDeclContext(), TP, Args,
+ /*NewIndex=*/AdjustedAliasTemplateArgs.size(),
+ getTemplateDepth(TP) + AdjustDepth);
+
+ auto NewTemplateArgument = Context.getCanonicalTemplateArgument(
+ Context.getInjectedTemplateArg(NewParam));
+ AdjustedAliasTemplateArgs.push_back(NewTemplateArgument);
+ }
+ // Template arguments used to transform the template arguments in
+ // DeducedResults.
+ SmallVector<TemplateArgument> TemplateArgsForBuildingRC(
+ F->getTemplateParameters()->size());
+ // Transform the transformed template args
MultiLevelTemplateArgumentList Args;
Args.setKind(TemplateSubstitutionKind::Rewrite);
- Args.addOuterTemplateArguments(TransformedArgs);
- ExprResult E = SemaRef.SubstExpr(RC, Args);
+ Args.addOuterTemplateArguments(AdjustedAliasTemplateArgs);
+
+ for (unsigned Index = 0; Index < DeduceResults.size(); ++Index) {
+ const auto &D = DeduceResults[Index];
+ if (D.isNull())
+ continue;
+ TemplateArgumentLoc Input =
+ SemaRef.getTrivialTemplateArgumentLoc(D, QualType(), SourceLocation{});
+ TemplateArgumentLoc Output;
+ if (!SemaRef.SubstTemplateArgument(Input, Args, Output)) {
+ assert(TemplateArgsForBuildingRC[Index].isNull() &&
+ "InstantiatedArgs must be null before setting");
+ TemplateArgsForBuildingRC[Index] = Output.getArgument();
+ }
+ }
+
+ // A list of template arguments for transforming the require-clause of F.
+ // It must contain the entire set of template argument lists.
+ MultiLevelTemplateArgumentList ArgsForBuildingRC;
+ ArgsForBuildingRC.setKind(clang::TemplateSubstitutionKind::Rewrite);
+ ArgsForBuildingRC.addOuterTemplateArguments(TemplateArgsForBuildingRC);
+ // For 2), if the underlying F is instantiated from a member template, we
need
+ // the entire template argument list, as the constraint AST in the
+ // require-clause of F remains completely uninstantiated.
+ //
+ // For example:
+ // template <typename T> // depth 0
+ // struct Outer {
+ // template <typename U>
+ // struct Foo { Foo(U); };
+ //
+ // template <typename U> // depth 1
+ // requires C<U>
+ // Foo(U) -> Foo<int>;
+ // };
+ // template <typename U>
+ // using AFoo = Outer<int>::Foo<U>;
+ //
+ // In this scenario, the deduction guide for `Foo` inside `Outer<int>`:
+ // - The occurrence of U in the require-expression is [depth:1, index:0]
+ // - The occurrence of U in the function parameter is [depth:0, index:0]
+ // - The template parameter of U is [depth:0, index:0]
+ // Particularly, for the `Foo` deduction guide inside the `Outer<int>`:
+ //
+ // - occurrence of U in the require-expression is [depth:1, index:0]
+ // - occurrence of U in the function parameter is [depth:0, index:0]
+ // - the template parameter of U is [depth:0, index:0]
+ //
+ // We add the outer template arguments which is [int] to the multi-level arg
+ // list to ensure that the occurrence U in `C<U>` will be replaced with int
+ // during the substitution.
+ if (F->getInstantiatedFromMemberTemplate()) {
----------------
zyn0217 wrote:
Ditto. Do we want to use the “primary” template after possibly multiple
transformations?
https://github.com/llvm/llvm-project/pull/90961
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