Fix error message for unknown -format argument.

-format=<foo>, -format <foo> and -b <foo> are all the same.
Previous code was intended to produce an error message with the
same spelling as given from the command line, but it actually
always printed out this string: "unknown -format= value:".
This is probably more confusing than "unknown -format value:".
So I changed the message.

llvm-svn: 284693

lld/ELF/Driver.cpp

@@ -581,13 +581,12 @@ void LinkerDriver::readConfigs(opt::InputArgList &Args) {
 }
 
 // Returns a value of "-format" option.
-static bool getBinaryOption(opt::Arg *Arg) {
-  StringRef S = Arg->getValue();
+static bool getBinaryOption(StringRef S) {
   if (S == "binary")
     return true;
   if (S == "elf" || S == "default")
     return false;
-  error("unknown " + Arg->getSpelling() + " format: " + S +
+  error("unknown -format value: " + S +
         " (supported formats: elf, default, binary)");
   return false;
 }
@@ -609,7 +608,7 @@ void LinkerDriver::createFiles(opt::InputArgList &Args) {
       Config->AsNeeded = true;
       break;
     case OPT_format:
-      Config->Binary = getBinaryOption(Arg);
+      Config->Binary = getBinaryOption(Arg->getValue());
       break;
     case OPT_no_as_needed:
       Config->AsNeeded = false;

lld/test/ELF/format-binary.test

@@ -7,6 +7,10 @@
 # RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
 # RUN: ld.lld %t.o -b binary %t.binary -b default %t.o -shared -o %t.out
 
+# RUN: not ld.lld -b foo > %t.log 2>&1
+# RUN: FileCheck -check-prefix=ERR %s < %t.log
+# ERR: error: unknown -format value: foo (supported formats: elf, default, binary)
+
 # CHECK:          Name: .data
 # CHECK-NEXT:     Type: SHT_PROGBITS
 # CHECK-NEXT:     Flags [