I was writing a new toolchain recently. I started with just the "cxx" tool.

I then discovered that gn silently ignores .c files in sources if there's no cc tool -- maybe it should say ".c file in sources but no cc file in toolchain?"

So I went and copied my cxx tool with the intent of creating a cc tool -- I changed c++ to cc in the command, but forgot to actually change the tool name from cxx to cc, so now my toolchain had two cxx tools but still no cc file. gn again did not diagnose this but just silently kept ignoring my c files. gn should probably also warn (or even error) on tool redefinitions.

Not terribly important since people probably don't write toolchains frequently, but I figured I should at least file a bug.