From 08419a75ac15b96959edfbdde9eebec72fad74a5 Mon Sep 17 00:00:00 2001
From: zebullax <zebullax@gmail.com>
Date: Thu, 30 Oct 2025 01:30:51 +0900
Subject: [PATCH] Fix `is_noexcept` for  implicit noexcept destructors when
 marked as default or deleted (#196)

---
 clang/lib/AST/ExprConstantMeta.cpp                    | 11 +++++------
 clang/lib/Sema/SemaReflect.cpp                        |  8 +++++++-
 .../reflection/member-classification.pass.cpp         | 10 ++++++++++
 3 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/clang/lib/AST/ExprConstantMeta.cpp b/clang/lib/AST/ExprConstantMeta.cpp
index c8240ec62251..15478d1cfd9f 100644
--- a/clang/lib/AST/ExprConstantMeta.cpp
+++ b/clang/lib/AST/ExprConstantMeta.cpp
@@ -1481,13 +1481,12 @@ static bool isFunctionOrMethodNoexcept(const QualType QT) {
   if (T->isFunctionProtoType()) {
     // This covers (virtual) methods & functions
     const auto *FPT = T->getAs<FunctionProtoType>();
-
     switch (FPT->getExceptionSpecType()) {
-    case EST_BasicNoexcept:
-    case EST_NoexceptTrue:
-      return true;
-    default:
-      return false;
+      case EST_BasicNoexcept:
+      case EST_NoexceptTrue:
+        return true;
+      default:
+        return false;
     }
   }
 
diff --git a/clang/lib/Sema/SemaReflect.cpp b/clang/lib/Sema/SemaReflect.cpp
index 483903acfb00..24896a1407be 100644
--- a/clang/lib/Sema/SemaReflect.cpp
+++ b/clang/lib/Sema/SemaReflect.cpp
@@ -349,7 +349,13 @@ public:
 
   void EnsureInstantiationOfExceptionSpec(SourceLocation Loc,
                                           FunctionDecl *FD) override {
-    S.InstantiateExceptionSpec(Loc, FD);
+    const FunctionProtoType *Proto = FD->getType()->castAs<FunctionProtoType>();
+    if (Proto->getExceptionSpecType() == EST_Uninstantiated) {
+      S.InstantiateExceptionSpec(Loc, FD);
+    }
+    if (Proto->getExceptionSpecType() == EST_Unevaluated) {
+      S.ResolveExceptionSpec(Loc, Proto);
+    }
   }
 
   QualType Substitute(TypeAliasTemplateDecl *TD,
diff --git a/libcxx/test/std/experimental/reflection/member-classification.pass.cpp b/libcxx/test/std/experimental/reflection/member-classification.pass.cpp
index cb3e1181dc52..be54037088c1 100644
--- a/libcxx/test/std/experimental/reflection/member-classification.pass.cpp
+++ b/libcxx/test/std/experimental/reflection/member-classification.pass.cpp
@@ -703,6 +703,16 @@ static_assert(!is_noexcept(type_of(^^EC::Something)));
 static_assert(!is_noexcept(^^E));
 static_assert(!is_noexcept(^^E_Something));
 static_assert(!is_noexcept(type_of(^^E_Something)));
+
+// Defaulted special members
+struct DelDest { ~DelDest() = delete; };
+static_assert(is_noexcept (^^DelDest::~DelDest));
+
+struct DefDest { ~DefDest() = default; };
+static_assert(is_noexcept (^^DefDest::~DefDest));
+
+struct EmptyStruct { };
+static_assert(is_noexcept (^^EmptyStruct::~EmptyStruct));
 } // namespace noexcept_functions
 
                               // ================