If clang didn't try to do the right thing based on the context it finds itself in, people would have to specify a lot more compiler flags to tell it what to do.

If clang didn't try to do the right thing based on the context it finds itself in, people would have to specify a lot more compiler flags to tell it what to do. Target triple, where libc is, where libstdc++ or libc++ is, what linker to use, what flags to pass the linker and so forth. This is much more annoying than `clang foo.c`.