[llvm-rc] Improve help printouts

[mstorsjo]

Summary

This gives more clear strings for Meson to check for in the output
of "$CMD /?" when detecting the kind of resource compiler tool, to
allow Meson to recognize llvm-rc.

[MaskRay]

This reminds me of D31199 (https://www.sigbus.info/software-compatibility-and-our-own-user-agent-problem).

Also, since we cannot update the existing configure scripts that are already generated and distributed as part of other programs, even if we improve autoconf, it would take many years until the problem would be resolved.

I think the Meson situation is better since projects don't bundle Meson in their released tarballs... I hope that we file a bug on https://github.com/mesonbuild/meson/issues and fix https://github.com/mesonbuild/meson/blob/1.1.1/mesonbuild/modules/windows.py#L97-L109 instead.

[mstorsjo]

In D154545#4475392, @MaskRay wrote:

This reminds me of D31199 (https://www.sigbus.info/software-compatibility-and-our-own-user-agent-problem).

Also, since we cannot update the existing configure scripts that are already generated and distributed as part of other programs, even if we improve autoconf, it would take many years until the problem would be resolved.

I think the Meson situation is better since projects don't bundle Meson in their released tarballs... I hope that we file a bug on https://github.com/mesonbuild/meson/issues and fix https://github.com/mesonbuild/meson/blob/1.1.1/mesonbuild/modules/windows.py#L97-L109 instead.

That’s probably reasonable - but we probably should land the other bits of this patch anyway. If you look at our current printouts, e.g. the original state of helpmsg.test, there’s literally nothing there that says llvm-rc or even LLVM in any form. So to get a reasonable regex for Meson to match against, we’d first need to improve the printout so that Meson has something reasonable to match against.

[mstorsjo]

Remove the "compatible with ..." part.

[hans]

lgtm

[eschwartz]

In D154545#4475392, @MaskRay wrote:

This reminds me of D31199 (https://www.sigbus.info/software-compatibility-and-our-own-user-agent-problem).

Also, since we cannot update the existing configure scripts that are already generated and distributed as part of other programs, even if we improve autoconf, it would take many years until the problem would be resolved.

I think the Meson situation is better since projects don't bundle Meson in their released tarballs... I hope that we file a bug on https://github.com/mesonbuild/meson/issues and fix https://github.com/mesonbuild/meson/blob/1.1.1/mesonbuild/modules/windows.py#L97-L109 instead.

Yes, thank you for this review comment. Unlike autotools, meson actually says "could not determine which type of $THING you are" and then errors out, which in theory means that proper handling gets directly included, so I'm quite happy to be able to detect llvm-rc as LLVM instead of Microsoft. If we ever need to treat them differently, we now can. And it's very easy to push updates to all users.

llvm/test/tools/llvm-rc/helpmsg.test

 ; RUN: llvm-rc /h > %t1
 ; RUN: llvm-rc '/?' > %t2
 ; RUN: diff %t1 %t2
 ; RUN: FileCheck -input-file=%t1 %s
 
-; CHECK:  OVERVIEW: Resource Converter
-; CHECK-DAG:  USAGE: rc [options] file...
+; CHECK:  OVERVIEW: LLVM Resource Converter
+; CHECK-DAG:  USAGE: llvm-rc [options] file...
 ; CHECK-DAG:  OPTIONS:
 ; CHECK-NEXT:    /?          Display this help and exit.
 ; CHECK-NEXT:    /C <value>  Set the codepage used for input strings.
 ; CHECK-NEXT:    /dry-run    Don't compile the input; only try to parse it.
 ; CHECK-NEXT:    /D <value>  Define a symbol for the C preprocessor.
 ; CHECK-NEXT:    /FO <value> Change the output file location.
 ; CHECK-NEXT:    /H          Display this help and exit.
 ; CHECK-NEXT:    /I <value>  Add an include path.
 ; CHECK-NEXT:    /LN <value> Set the default language name.
 ; CHECK-NEXT:    /L <value>  Set the default language identifier.
 ; CHECK-NEXT:    /no-preprocess Don't try to preprocess the input file.
 ; CHECK-NEXT:    /N          Null-terminate all strings in the string table.
 ; CHECK-NEXT:    /U <value>  Undefine a symbol for the C preprocessor.
 ; CHECK-NEXT:    /V          Be verbose.
 ; CHECK-NEXT:    /X          Ignore 'include' variable.
 ; CHECK-NEXT:    /Y          Suppress warnings on duplicate resource IDs.

llvm/tools/llvm-rc/llvm-rc.cpp

RcOptions parseRcOptions(ArrayRef<const char *> ArgsArr,
                          ArrayRef<const char *> InputArgsArray) {
   RcOptTable T;
   RcOptions Opts;
   unsigned MAI, MAC;
   opt::InputArgList InputArgs = T.ParseArgs(ArgsArr, MAI, MAC);
 
   // The tool prints nothing when invoked with no command-line arguments.
   if (InputArgs.hasArg(OPT_help)) {
-    T.printHelp(outs(), "rc [options] file...", "Resource Converter", false);
+    T.printHelp(outs(), "llvm-rc [options] file...", "LLVM Resource Converter",
+                false);
     exit(0);
   }
 
   std::vector<std::string> InArgsInfo = InputArgs.getAllArgValues(OPT_INPUT);
   InArgsInfo.insert(InArgsInfo.end(), InputArgsArray.begin(),
                     InputArgsArray.end());
   if (InArgsInfo.size() != 1) {
     fatalError("Exactly one input file should be provided.");