[clang] [clang-repl] adding documentation and information for %commands (PR #150348)

[David Spickett via cfe-commits]

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@@ -347,7 +348,15 @@ int main(int argc, const char **argv) {
     }
   }
 
+  // if we add more % commands, there should be better architecture than this
+  const char *help_output = "%help\tlist clang-repl %commands\n"
+                            "%undo\tundo the previous input\n"
+                            "%quit\texit clang-repl\n";
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DavidSpickett wrote:

You should add %lib here as well.

https://github.com/llvm/llvm-project/pull/150348