[llvm-nm] Include the text "@FILE" in the output of --help

[mstorsjo]

Summary

libtool requires this text to be present, in order to conclude that the tool supports response files.

[rupprecht]

I'm not sure @FILE syntax is actually supported by llvm-nm. At least, I can't find any unit tests that test it, and @ is not present in llvm-nm.cpp. I think that change should come first?

[mstorsjo]

In D53064#1260876, @rupprecht wrote:

I'm not sure @FILE syntax is actually supported by llvm-nm. At least, I can't find any unit tests that test it, and @ is not present in llvm-nm.cpp. I think that change should come first?

It does support it just fine right now (even if there's no explicit unit test for it). llvm-nm.cpp calls ParseCommandLineOptions, which internally calls ExpandResponseFiles, so this is implicit in more or less every llvm tool.

[rnk]

lgtm

[rupprecht]

In D53064#1260942, @mstorsjo wrote:

In D53064#1260876, @rupprecht wrote:

I'm not sure @FILE syntax is actually supported by llvm-nm. At least, I can't find any unit tests that test it, and @ is not present in llvm-nm.cpp. I think that change should come first?

It does support it just fine right now (even if there's no explicit unit test for it). llvm-nm.cpp calls ParseCommandLineOptions, which internally calls ExpandResponseFiles, so this is implicit in more or less every llvm tool.

I see. Would you mind adding a simple test that llvm-nm actually handles @FILE as a resource file and not as a file? Not all tools use ParseCommandLineOptions, so it's not unreasonable that someone may need to change llvm-nm to avoid it for some reason.

[mstorsjo]

Added a testcase that actually uses a response file. Will commit later with @rnk's approval unless there's further comments.

[rupprecht]

lgtm, thanks for the test!

test/tools/llvm-nm/X86/response-file.test

+# RUN: echo "-P %p/Inputs/hello.obj.elf-x86_64" > %t-response
+# RUN: llvm-nm @%t-response | FileCheck %s
+
+CHECK: main T 0 0
+CHECK: puts U 0 0

test/tools/llvm-nm/libtool-response-file.test

+RUN: llvm-nm --help | FileCheck %s
+Check that the output of llvm-nm --help contains the literal text @FILE; this
+indicates to libtool that llvm-nm does support response files.
+CHECK: @FILE

tools/llvm-nm/llvm-nm.cpp

cl::opt<bool> NoDyldInfo("no-dyldinfo",
                                   "Mach-O only"));
 cl::opt<bool> DyldInfoOnly("dyldinfo-only",
                            cl::desc("Show only symbols from the dyldinfo, "
                                     "Mach-O only"));
 
 cl::opt<bool> NoLLVMBitcode("no-llvm-bc",
                             cl::desc("Disable LLVM bitcode reader"));
 
+cl::extrahelp HelpResponse("\nPass @FILE as argument to read options from FILE.\n");
+
 bool PrintAddress = true;
 
 bool MultipleFiles = false;
 
 bool HadError = false;
 
 std::string ToolName;
 } // anonymous namespace