[clang] Expand annotation check for -Wunique-object-duplication on Windows. (PR #145944)

[Devon Loehr via cfe-commits]

https://github.com/DKLoehr updated https://github.com/llvm/llvm-project/pull/145944

>From 662c5d5419312f379bad52955eac2bb6be00dfd9 Mon Sep 17 00:00:00 2001
From: Devon Loehr <dloehr at google.com>
Date: Thu, 26 Jun 2025 17:50:27 +0000
Subject: [PATCH] Check containing class for everything, not just variables

---
 clang/lib/Sema/SemaDecl.cpp                   | 14 +++---
 .../test/SemaCXX/unique_object_duplication.h  | 45 +++++++++++++++++--
 2 files changed, 47 insertions(+), 12 deletions(-)

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index a60a558155e69..246e0395435bb 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -13524,21 +13524,19 @@ bool Sema::GloballyUniqueObjectMightBeAccidentallyDuplicated(
 
   // The target is "hidden" (from the dynamic linker) if:
   // 1. On posix, it has hidden visibility, or
-  // 2. On windows, it has no import/export annotation
+  // 2. On windows, it has no import/export annotation, and neither does the
+  // class which directly contains it.
   if (Context.getTargetInfo().shouldDLLImportComdatSymbols()) {
     if (Target->hasAttr<DLLExportAttr>() || Target->hasAttr<DLLImportAttr>())
       return false;
 
     // If the variable isn't directly annotated, check to see if it's a member
     // of an annotated class.
-    const VarDecl *VD = dyn_cast<VarDecl>(Target);
+    const CXXRecordDecl *Ctx =
+        dyn_cast<CXXRecordDecl>(Target->getDeclContext());
+    if (Ctx && (Ctx->hasAttr<DLLExportAttr>() || Ctx->hasAttr<DLLImportAttr>()))
+      return false;
 
-    if (VD && VD->isStaticDataMember()) {
-      const CXXRecordDecl *Ctx = dyn_cast<CXXRecordDecl>(VD->getDeclContext());
-      if (Ctx &&
-          (Ctx->hasAttr<DLLExportAttr>() || Ctx->hasAttr<DLLImportAttr>()))
-        return false;
-    }
   } else if (Lnk.getVisibility() != HiddenVisibility) {
     // Posix case
     return false;
diff --git a/clang/test/SemaCXX/unique_object_duplication.h b/clang/test/SemaCXX/unique_object_duplication.h
index bd0ee6bd14d64..a5da767b79474 100644
--- a/clang/test/SemaCXX/unique_object_duplication.h
+++ b/clang/test/SemaCXX/unique_object_duplication.h
@@ -173,10 +173,6 @@ namespace GlobalTest {
 
     // Always visible
     VISIBLE static inline float allowedStaticMember2 = 0.0;
-
-    // Tests here are sparse because the AddrTest case below will define plenty
-    // more, which aren't problematic to define (because they're immutable), but
-    // may still cause problems if their address is taken.
   };
 
   inline float Test::disallowedStaticMember2 = 2.3; // hidden-warning {{'disallowedStaticMember2' may be duplicated when built into a shared library: it is mutable, with external linkage and hidden visibility}}
@@ -211,3 +207,44 @@ inline int allowedTemplate2 = 0;
 template int allowedTemplate2<int>;
 
 } // namespace TemplateTest
+
+/******************************************************************************
+ * Case four: Nested classes
+ ******************************************************************************/
+
+namespace NestedClassTest {
+// Unlike visibility, declexport annotations do not propagate down to nested
+// classes. Hence on windows, we only avoid duplication of class members if
+// their immediate containing class is annotated. On posix, we get avoid
+// duplication if any containing class is annotated.
+
+class VISIBLE Outer {
+  // Visible because their class is exported
+  inline static int allowedOuterMember = 0;
+  int* allowedOuterFunction() {
+    static int allowed = 0;
+    return &allowed;
+  }
+
+  // No annotation, and visibility is only propagated on posix.
+  class HiddenOnWindows {
+    inline static int disallowedInnerMember = 0; // windows-warning {{'disallowedInnerMember' may be duplicated when built into a shared library: it is mutable, with external linkage and no import/export annotation}}
+
+
+    int* disallowedInnerFunction() {
+      static int disallowed = 0; // windows-warning {{'disallowed' may be duplicated when built into a shared library: it is mutable, with external linkage and no import/export annotation}}
+      return &disallowed;
+    }
+  };
+
+  class VISIBLE AlwaysVisible {
+    inline static int allowedInnerMember = 0;
+
+    int* allowedInnerFunction() {
+      static int allowed = 0;
+      return &allowed;
+    }
+  };
+};
+
+}
\ No newline at end of file