[lld-link] Warn on exported deleting dtor

MSVC linker has this [[ https://docs.microsoft.com/en-us/cpp/error-messages/tool-errors/linker-tools-warning-lnk4102?view=msvc-160 | warning]], so lld-link should also warn on this.

Differential Revision: https://reviews.llvm.org/D100606

diff --git a/lld/COFF/Writer.cpp b/lld/COFF/Writer.cpp
index 09c456e..422a85c 100644 (file)
--- a/lld/COFF/Writer.cpp
+++ b/lld/COFF/Writer.cpp
@@ -1078,6 +1078,10 @@ void Writer::createExportTable() {
     edataStart = edataSec->chunks.front();
     edataEnd = edataSec->chunks.back();
   }
+  // Warn on exported deleting destructor.
+  for (auto e : config->exports)
+    if (e.sym && e.sym->getName().startswith("??_G"))
+      warn("export of deleting dtor: " + toString(*e.sym));
 }
 
 void Writer::removeUnusedSections() {

diff --git a/lld/test/COFF/export-deleting-dtor.s b/lld/test/COFF/export-deleting-dtor.s
new file mode 100644 (file)
index 0000000..5d7b39c
--- /dev/null
+++ b/lld/test/COFF/export-deleting-dtor.s
@@ -0,0 +1,26 @@
+# REQUIRES: x86
+
+# RUN: llvm-mc -triple=x86_64-windows-msvc -defsym drectve=0 %s -filetype=obj -o %t.obj
+# RUN: echo "EXPORTS  ??_GFoo@@UEAAPEAXI@Z" > %t.def
+
+# RUN: lld-link %t.obj -entry:dllmain -dll -export:'??_GFoo@@UEAAPEAXI@Z' -out:%t.1.dll 2>&1 | FileCheck %s
+
+# RUN: lld-link %t.obj -entry:dllmain -dll -def:%t.def -out:%t.2.dll 2>&1 | FileCheck %s
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64-windows-msvc -defsym drectve=1 %s -o %t.drectve.obj
+# RUN: lld-link %t.drectve.obj -entry:dllmain -dll -out:%t.3.dll 2>&1 | FileCheck %s
+
+# CHECK: export of deleting dtor:{{.*}}Foo{{.*}}
+
+        .text
+        .globl  dllmain
+        .globl  "??_GFoo@@UEAAPEAXI@Z"
+dllmain:
+        ret
+"??_GFoo@@UEAAPEAXI@Z":
+        ret
+
+.if drectve==1
+        .section .drectve
+        .ascii "-export:??_GFoo@@UEAAPEAXI@Z"
+.endif