[TableGen] [NFC] Make argv0 const

[abrachet]

Summary

argv0 was never being modified. No changes made except to the type.

[RKSimon]

LGTM - please improve the commit message to explain that argv0 is only ever used forwarded to methods that use it as a const char*

llvm/include/llvm/TableGen/Main.h

 
 class raw_ostream;
 class RecordKeeper;
 
 /// Perform the action using Records, and write output to OS.
 /// Returns true on error, false otherwise.
 using TableGenMainFn = bool (raw_ostream &OS, RecordKeeper &Records);
 
-int TableGenMain(char *argv0, TableGenMainFn *MainFn);
+int TableGenMain(const char *argv0, TableGenMainFn *MainFn);
 
 } // end namespace llvm
 
 #endif // LLVM_TABLEGEN_MAIN_H

llvm/lib/TableGen/Main.cpp

static int createDependencyFile(const TGParser &Parser, const char *argv0) {
   for (const auto &Dep : Parser.getDependencies()) {
     DepOut.os() << ' ' << Dep;
   }
   DepOut.os() << "\n";
   DepOut.keep();
   return 0;
 }
 
-int llvm::TableGenMain(char *argv0, TableGenMainFn *MainFn) {
+int llvm::TableGenMain(const char *argv0, TableGenMainFn *MainFn) {
   RecordKeeper Records;
 
   // Parse the input file.
   ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
       MemoryBuffer::getFileOrSTDIN(InputFilename);
   if (std::error_code EC = FileOrErr.getError())
     return reportError(argv0, "Could not open input file '" + InputFilename +
                                   "': " + EC.message() + "\n");