================
@@ -18563,6 +18556,58 @@ ExprResult Sema::ActOnCXXReflectExpr(SourceLocation
CaretCaretLoc,
ExprResult Sema::BuildCXXReflectExpr(SourceLocation CaretCaretLoc,
TypeSourceInfo *TSI) {
+ QualType QT = TSI->getType();
+ SourceLocation TypeLoc = TSI->getTypeLoc().getBeginLoc();
+
+ // Don't bother supporting VLAs here.
+ if (QT->isVariablyModifiedType()) {
+ Diag(TypeLoc, diag::err_reflect_variably_modified_type) << QT;
+ return ExprError();
+ }
+
+ // Canonicalize template arguments of alias template specializations.
+ //
+ // A parsed TST retains template arguments as written. Rebuild it with the
+ // canonical template declaration and normalized arguments so equivalent
+ // alias specializations have the same reflection identity.
+ //
+ // FIXME: This does mean that e.g. ^^A<1+2> becomes ^^A<3>; we might
+ // want to retain the original arguments somehow, but we need to make sure
+ // that doing so doesn't change the fact that ^^A<1+2> == ^^A<3>.
+ if (const auto *T = dyn_cast<TemplateSpecializationType>(QT.getTypePtr());
+ T && isTypeAliasAsReflectionName(QT)) {
+ auto TL = TSI->getTypeLoc().castAs<TemplateSpecializationTypeLoc>();
+ TemplateArgumentListInfo Args(TL.getLAngleLoc(), TL.getRAngleLoc());
+ for (unsigned I = 0; I != TL.getNumArgs(); ++I)
+ Args.addArgument(TL.getArgLoc(I));
+ auto [Name, DefaultArgs] =
+ T->getTemplateName().getTemplateDeclAndDefaultArgs();
+ auto *TD = cast<TypeAliasTemplateDecl>(Name.getAsTemplateDecl());
+ CheckTemplateArgumentInfo CTAI;
+ if (CheckTemplateArgumentList(TD, TL.getTemplateNameLoc(), Args,
+ DefaultArgs, /*PartialTemplateArgs=*/false,
+ CTAI))
+ return ExprError();
+
+ for (auto &Arg : CTAI.CanonicalConverted)
+ Arg.setIsDefaulted(false);
+ QT = Context.getTemplateSpecializationType(
+ ElaboratedTypeKeyword::None, TemplateName(TD->getCanonicalDecl()),
+ CTAI.CanonicalConverted, /*CanonicalArgs=*/{}, T->getAliasedType());
+ TSI = Context.getTrivialTypeSourceInfo(QT, TypeLoc);
+ }
+
+ // [expr.reflect]/5.1 makes reflection-names found through using-declarations
+ // ill-formed. A cv-qualified or elaborated type-id instead reflects its
type.
----------------
ojhunt wrote:
Do you happen to know why this restriction exists? (Off hand, I can always read
the entire paper if I decide I care enough :D )
https://github.com/llvm/llvm-project/pull/232074
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