[llvm-objcopy] Fix the exit code

[alexander-shaposhnikov]

Summary

Set the exit code (llvm-objcopy/llvm-strip) to 1 if no arguments are specified
(binutils objcopy does the same).

Test plan: make check-all

[alexander-shaposhnikov]

in case of misuse print the help message to stderr (like binutils objcopy does)

[jakehehrlich]

LGTM I checked that this is consistent with objcopy (and it would seem other tools as well). Seems acceptable to me as is.

[alexander-shaposhnikov]

tools/llvm-objcopy/llvm-objcopy.cpp

492–497

(just in case - this class doesn't have empty() (yet) - that's why it's a little bit more verbose than probably it could be)

[jhenderson]

LGTM.

test/tools/llvm-objcopy/help-message.test

+# RUN: llvm-objcopy --help | FileCheck --check-prefix=CHECK-OBJCOPY %s
+# RUN: not llvm-objcopy | FileCheck --check-prefix=CHECK-OBJCOPY %s
+
+# RUN: llvm-strip --help | FileCheck --check-prefix=CHECK-STRIP %s
+# RUN: not llvm-strip | FileCheck --check-prefix=CHECK-STRIP %s
+
+# CHECK-OBJCOPY: USAGE: llvm-objcopy
+# CHECK-STRIP:   USAGE: llvm-strip

tools/llvm-objcopy/llvm-objcopy.cpp

 // ParseObjcopyOptions returns the config and sets the input arguments. If a
 // help flag is set then ParseObjcopyOptions will print the help messege and
 // exit.
 CopyConfig ParseObjcopyOptions(ArrayRef<const char *> ArgsArr) {
   ObjcopyOptTable T;
   unsigned MissingArgumentIndex, MissingArgumentCount;
   llvm::opt::InputArgList InputArgs =
       T.ParseArgs(ArgsArr, MissingArgumentIndex, MissingArgumentCount);
   
-  if (InputArgs.size() == 0 || InputArgs.hasArg(OBJCOPY_help)) {
+  if (InputArgs.size() == 0) {
+    T.PrintHelp(outs(), "llvm-objcopy <input> [ <output> ]", "objcopy tool");
+    exit(1);
+  }
+  
+  if (InputArgs.hasArg(OBJCOPY_help)) {
     T.PrintHelp(outs(), "llvm-objcopy <input> [ <output> ]", "objcopy tool");
     exit(0);
   }
 
   SmallVector<const char *, 2> Positional;
 
   for (auto Arg : InputArgs.filtered(OBJCOPY_UNKNOWN))
     error("unknown argument '" + Arg->getAsString(InputArgs) + "'");

 // help flag is set then ParseStripOptions will print the help messege and
 // exit.
 CopyConfig ParseStripOptions(ArrayRef<const char *> ArgsArr) {
   StripOptTable T;
   unsigned MissingArgumentIndex, MissingArgumentCount;
   llvm::opt::InputArgList InputArgs =
       T.ParseArgs(ArgsArr, MissingArgumentIndex, MissingArgumentCount);
 
-  if (InputArgs.size() == 0 || InputArgs.hasArg(STRIP_help)) {
+  if (InputArgs.size() == 0) {
+    T.PrintHelp(outs(), "llvm-strip <input> [ <output> ]", "strip tool");
+    exit(1);
+  }
+  
+  if (InputArgs.hasArg(STRIP_help)) {
     T.PrintHelp(outs(), "llvm-strip <input> [ <output> ]", "strip tool");
     exit(0);
   }
 
   SmallVector<const char *, 2> Positional;
   for (auto Arg : InputArgs.filtered(STRIP_UNKNOWN))
     error("unknown argument '" + Arg->getAsString(InputArgs) + "'");
   for (auto Arg : InputArgs.filtered(STRIP_INPUT))