[COFF] Don't let /def override /out filename

[rnk]

Summary

This also delays setting the output filename based on the first input
argument until after processing /def.

Fixes PR32354

[ruiu]

So the priority of inferring output path is the first object file name, a module definition file, or /out option, in increasing order of priority. I wonder if it is easier to parse arguments in this order and set Config->OutputPath uncoditionally.

[rnk]

I think it would be better if Config->OutputFile is always either empty or the true final output name. Otherwise we might query it somewhere in the middle of options processing and get an incorrect value.

[rnk]

I'm going to go ahead and land this to try to green the Chromium bots. We can reorganize later if we like.

lld/trunk/COFF/Driver.cpp

auto Future =
       std::make_shared<std::future<MBErrPair>>(createFutureForFile(Path));
   std::string PathStr = Path;
   enqueueTask([=]() {
     auto MBOrErr = Future->get();
     if (MBOrErr.second)
       fatal(MBOrErr.second, "could not open " + PathStr);
     Driver->addBuffer(std::move(MBOrErr.first));
   });
-
-  if (Config->OutputFile == "")
-    Config->OutputFile = getOutputPath(Path);
 }
 
 void LinkerDriver::addArchiveBuffer(MemoryBufferRef MB, StringRef SymName,
                                     StringRef ParentName) {
   file_magic Magic = identify_magic(MB.getBuffer());
   if (Magic == file_magic::coff_import_library) {
     Symtab.addFile(make<ImportFile>(MB));
     return;
for (auto *Arg : Args.filtered(OPT_delayload)) {
     Config->DelayLoads.insert(StringRef(Arg->getValue()).lower());
     if (Config->Machine == I386) {
       Config->DelayLoadHelper = addUndefined("___delayLoadHelper2@8");
     } else {
       Config->DelayLoadHelper = addUndefined("__delayLoadHelper2");
     }
   }
 
+  // Set default image name if neither /out or /def set it.
+  if (Config->OutputFile.empty()) {
+    Config->OutputFile =
+        getOutputPath((*Args.filtered_begin(OPT_INPUT))->getValue());
+  }
+
   // Set default image base if /base is not given.
   if (Config->ImageBase == uint64_t(-1))
     Config->ImageBase = getDefaultImageBase();
 
   Symtab.addRelative(mangle("__ImageBase"), 0);
   if (Config->Machine == I386) {
     Config->SEHTable = Symtab.addRelative("___safe_se_handler_table", 0);
     Config->SEHCount = Symtab.addAbsolute("___safe_se_handler_count", 0);

lld/trunk/COFF/ModuleDef.cpp

case KwExports:
           unget();
           return;
         }
         parseExport();
       }
     case KwHeapsize:
       parseNumbers(&Config->HeapReserve, &Config->HeapCommit);
       return;
-    case KwLibrary:
-      parseName(&Config->OutputFile, &Config->ImageBase);
-      if (!StringRef(Config->OutputFile).endswith_lower(".dll"))
-        Config->OutputFile += ".dll";
-      return;
     case KwStacksize:
       parseNumbers(&Config->StackReserve, &Config->StackCommit);
       return;
-    case KwName:
-      parseName(&Config->OutputFile, &Config->ImageBase);
+    case KwLibrary:
+    case KwName: {
+      bool IsDll = Tok.K == KwLibrary; // Check before parseName.
+      std::string Name;
+      parseName(&Name, &Config->ImageBase);
+
+      // Append the appropriate file extension if not already present.
+      StringRef Ext = IsDll ? ".dll" : ".exe";
+      if (!StringRef(Name).endswith_lower(Ext))
+        Name += Ext;
+
+      // Set the output file, but don't override /out if it was already passed.
+      if (Config->OutputFile.empty())
+        Config->OutputFile = Name;
       return;
+    }
     case KwVersion:
       parseVersion(&Config->MajorImageVersion, &Config->MinorImageVersion);
       return;
     default:
       fatal("unknown directive: " + Tok.Value);
     }
   }
 

lld/trunk/test/COFF/def-name.test

+# REQUIRES: winres
+
+# RUN: rm -rf %t
+# RUN: mkdir -p %t
+# RUN: cd %t
+# RUN: yaml2obj < %p/Inputs/ret42.yaml > in.obj
+
+# RUN: lld-link /entry:main in.obj
+# RUN: lld-link /entry:main /dll in.obj
+
+# RUN: echo -e "NAME foo\n" > fooexe.def
+# RUN: echo -e "LIBRARY foo\n" > foodll.def
+# RUN: lld-link /entry:main /def:fooexe.def in.obj
+# RUN: lld-link /entry:main /def:foodll.def /dll in.obj
+
+# RUN: lld-link /entry:main /out:bar.exe /def:fooexe.def in.obj
+# RUN: lld-link /entry:main /out:bar.dll /def:foodll.def /dll in.obj
+
+# RUN: llvm-readobj in.exe | FileCheck %s
+# RUN: llvm-readobj in.dll | FileCheck %s
+
+# RUN: llvm-readobj foo.exe | FileCheck %s
+# RUN: llvm-readobj foo.dll | FileCheck %s
+
+# RUN: llvm-readobj bar.exe | FileCheck %s
+# RUN: llvm-readobj bar.dll | FileCheck %s
+
+CHECK: File: