Remove field to avoid ABI break

Author: aganea

lld/COFF/Config.h

@@ -313,7 +313,6 @@ struct Configuration {
   bool warnDebugInfoUnusable = true;
   bool warnLongSectionNames = true;
   bool warnStdcallFixup = true;
-  bool warnExportedDllMain = true;
   bool incremental = true;
   bool integrityCheck = false;
   bool killAt = false;

lld/COFF/Driver.cpp

@@ -1625,8 +1625,6 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
         config->warnLocallyDefinedImported = false;
       else if (s == "longsections")
         config->warnLongSectionNames = false;
-      else if (s == "exporteddllmain")
-        config->warnExportedDllMain = false;
       // Other warning numbers are ignored.
     }
   }

lld/COFF/InputFiles.cpp

@@ -131,15 +131,12 @@ static bool fixupDllMain(COFFLinkerContext &ctx, llvm::object::Archive *file,
             file->getFileName() +
                 ": could not get the buffer for a child buffer of the archive");
   if (identify_magic(mb.getBuffer()) == file_magic::coff_import_library) {
-    if (ctx.config.warnExportedDllMain) {
-      // We won't place DllMain symbols in the symbol table if they are
-      // coming from a import library. This message can be ignored with the flag
-      // '/ignore:exporteddllmain'
-      Warn(ctx)
-          << file->getFileName()
-          << ": skipping exported DllMain symbol [exporteddllmain]\nNOTE: this "
-             "might be a mistake when the DLL/library was produced.";
-    }
+    // We won't place DllMain symbols in the symbol table if they are
+    // coming from a import library. This message can be ignored with the flag
+    // '/ignore:exporteddllmain'
+    Warn(ctx) << file->getFileName()
+              << ": skipping imported DllMain symbol\nNOTE: this "
+                 "might be a mistake when the DLL/library was produced.";
     skipDllMain = true;
     return true;
   }

lld/test/COFF/exported-dllmain.test

@@ -14,11 +14,9 @@ RUN: lld-link -lib c.obj -out:c.lib
 
 ### Later, if b.lib is provided before other libs/objs that export DllMain statically, we previously were using the dllimported DllMain from b.lib, which is wrong.
 RUN: lld-link a.obj b.lib c.lib -dll -out:out.dll -entry:DllMain 2>&1 | FileCheck -check-prefix=WARN %s
-RUN: lld-link a.obj b.lib c.lib -dll -out:out.dll -entry:DllMain -ignore:exporteddllmain 2>&1 | FileCheck -check-prefix=IGNORED --allow-empty %s
 RUN: llvm-objdump --private-headers -d out.dll | FileCheck -check-prefix=DISASM %s
 
-WARN: lld-link: warning: b.lib: skipping exported DllMain symbol [exporteddllmain]
-IGNORED-NOT: lld-link: warning: b.lib: skipping exported DllMain symbol [exporteddllmain]
+WARN: lld-link: warning: b.lib: skipping imported DllMain symbol
 
 DISASM: The Import Tables:
 DISASM: DLL Name: b.dll