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In both the Unix and Windows variants, std::getenv was called and the result passed directly to a function accepting a StringRef. This isn't OK because it might return a null pointer and that causes the StringRef constructor to assert (and generally produces crash-prone code if asserts are disabled). Fix this by independently testing the result as non-null prior to splitting things. This in turn uncovered another bug in the Unix variant where it would infinitely recurse if PATH="", or after this fix if PATH isn't set. There is no need to recurse at all. Slightly re-arrange the code to make it clear that we can just fixup the Paths argument based on the environment if we find anything. I don't know of a particularly useful way to test these routines in LLVM. I'll commit a test to Clang that ensures that its driver correctly handles various settings of PATH. However, I have no idea how to correctly write a Windows test for the PATHEXT change. Any Windows developers who could provide such a test, please have at. =D Many thanks to Nick Lewycky and others for helping debug this. =/ It was quite nasty for us to track down. llvm-svn: 223099
llvm/lib/Support/Unix README =========================== This directory provides implementations of the lib/System classes that are common to two or more variants of UNIX. For example, the directory structure underneath this directory could look like this: Unix - only code that is truly generic to all UNIX platforms Posix - code that is specific to Posix variants of UNIX SUS - code that is specific to the Single Unix Specification SysV - code that is specific to System V variants of UNIX As a rule, only those directories actually needing to be created should be created. Also, further subdirectories could be created to reflect versions of the various standards. For example, under SUS there could be v1, v2, and v3 subdirectories to reflect the three major versions of SUS.