Simplify llvm-cat -help

[serge-sans-paille]

Summary

Only output options that are directly relevant, and leave the remainder to the -help-hidden flag.

[jhenderson]

Please remember to include the context!

[serge-sans-paille]

Include full context

[serge-sans-paille]

For reference, and following the idea that we should not filter out relevant options, her eis the original output:

OVERVIEW: Module concatenation
USAGE: llvm-cat [options] <input  files>

OPTIONS:

Color Options:

  --color                            - Use colors in output (default=autodetect)

General options:

  -b                                 - Whether to perform binary concatenation
  --cost-kind=<value>                - Target cost kind
    =throughput                      -   Reciprocal throughput
    =latency                         -   Instruction latency
    =code-size                       -   Code size
  -o=<filename>                      - Output filename
  --remarks-yaml-string-table        - 
  --safepoint-ir-verifier-print-only - 
  --time-trace-granularity=<uint>    - Minimum time granularity (in microseconds) traced by time profiler
  --verify-region-info               - Verify region info (time consuming)

Generic Options:

  --help                             - Display available options (--help-hidden for more)
  --help-list                        - Display list of available options (--help-list-hidden for more)
  --version                          - Display the version of this program

and the new output

OVERVIEW: Module concatenation
USAGE: llvm-cat [options] <input  files>

OPTIONS:

Generic Options:

  --help        - Display available options (--help-hidden for more)
  --help-list   - Display list of available options (--help-list-hidden for more)
  --version     - Display the version of this program

llvm-cat Options:

  -b            - Whether to perform binary concatenation
  -o=<filename> - Output filename

[t.p.northover]

Looks fine to me.

llvm/tools/llvm-cat/llvm-cat.cpp

 #include <algorithm>
 #include <memory>
 #include <string>
 #include <system_error>
 #include <vector>
 
 using namespace llvm;
 
+cl::OptionCategory CatCategory("llvm-cat Options");
+
 static cl::opt<bool>
-    BinaryCat("b", cl::desc("Whether to perform binary concatenation"));
+    BinaryCat("b", cl::desc("Whether to perform binary concatenation"),
+              cl::cat(CatCategory));
 
 static cl::opt<std::string> OutputFilename("o", cl::Required,
                                            cl::desc("Output filename"),
-                                           cl::value_desc("filename"));
+                                           cl::value_desc("filename"),
+                                           cl::cat(CatCategory));
 
 static cl::list<std::string> InputFilenames(cl::Positional, cl::ZeroOrMore,
-                                            cl::desc("<input  files>"));
+                                            cl::desc("<input  files>"),
+                                            cl::cat(CatCategory));
 
 int main(int argc, char **argv) {
+  cl::HideUnrelatedOptions(CatCategory);
   cl::ParseCommandLineOptions(argc, argv, "Module concatenation");
 
   ExitOnError ExitOnErr("llvm-cat: ");
   LLVMContext Context;
 
   SmallVector<char, 0> Buffer;
   BitcodeWriter Writer(Buffer);
   if (BinaryCat) {