[LLD][ELF] - Check options before processing the -v/-version options.

[grimar]

Summary

This is https://bugs.llvm.org/show_bug.cgi?id=39289.

Currently both gold and bfd report errors about invalid options values
even with -v/-versions. But LLD does not.

This makes complicated to check the options available when LLD is used
(see Linux kernel issue: https://github.com/ClangBuiltLinux/linux/issues/31#issuecomment-429683000)

Patch makes LLD behavior to be consistent with GNU linkers.

[ruiu]

Honestly I don't think this is worth "fixing" because this is not a bug. We shouldn't bother copying this much details of GNU linkers' behavior. Being said that, since this patch does not append any complexity to the linker, I'm fine with that. LGTM

ELF/Driver.cpp

void LinkerDriver::main(ArrayRef<const char *> ArgsArr) {
   // it is not easy to improve it to recognize LLD as a GNU compatible
   // linker in a timely manner. Even if we can make it, there are still a
   // lot of "configure" scripts out there that are generated by old version
   // of Libtool. We cannot convince every software developer to migrate to
   // the latest version and re-generate scripts. So we have this hack.
   if (Args.hasArg(OPT_v) || Args.hasArg(OPT_version))
     message(getLLDVersion() + " (compatible with GNU linkers)");
 
-  // The behavior of -v or --version is a bit strange, but this is
-  // needed for compatibility with GNU linkers.
-  if (Args.hasArg(OPT_v) && !Args.hasArg(OPT_INPUT))
-    return;
-  if (Args.hasArg(OPT_version))
-    return;
-
   if (const char *Path = getReproduceOption(Args)) {
     // Note that --reproduce is a debug option so you can ignore it
     // if you are trying to understand the whole picture of the code.
     Expected<std::unique_ptr<TarWriter>> ErrOrWriter =
         TarWriter::create(Path, path::stem(Path));
     if (ErrOrWriter) {
       Tar = ErrOrWriter->get();
       Tar->append("response.txt", createResponseFile(Args));
       Tar->append("version.txt", getLLDVersion() + "\n");
       make<std::unique_ptr<TarWriter>>(std::move(*ErrOrWriter));
     } else {
       error(Twine("--reproduce: failed to open ") + Path + ": " +
             toString(ErrOrWriter.takeError()));
     }
   }
 
   readConfigs(Args);
   checkZOptions(Args);
+
+  // The behavior of -v or --version is a bit strange, but this is
+  // needed for compatibility with GNU linkers.
+  if (Args.hasArg(OPT_v) && !Args.hasArg(OPT_INPUT))
+    return;
+  if (Args.hasArg(OPT_version))
+    return;
+
   initLLVM();
   createFiles(Args);
   if (errorCount())
     return;
 
   inferMachineType();
   setConfigs(Args);
   checkOptions(Args);

test/ELF/driver.test

 
 ## "-output=foo" is equivalent to "-o utput=foo".
 # RUN: not ld.lld %t -output=/no/such/file 2>&1 | FileCheck -check-prefix=ERR9 %s
 # ERR9: cannot open output file utput=/no/such/file
 
 # RUN: not ld.lld %t -z foo 2>&1 | FileCheck -check-prefix=ERR10 %s
 # ERR10: unknown -z value: foo
 
+## Check we report "unknown -z value" error even with -v.
+# RUN: not ld.lld %t -z foo -v 2>&1 | FileCheck -check-prefix=ERR10 %s
+
 # RUN: not ld.lld %t -z max-page-size 2>&1 | FileCheck -check-prefix=ERR11 %s
 # ERR11: unknown -z value: max-page-size
 
 .globl _start
 _start:
   nop