[llvm-dev] [llvm-rc] absolute.test failing (original) (raw)

Nico Weber via llvm-dev llvm-dev at lists.llvm.org
Thu Jan 10 06:59:45 PST 2019

On Thu, Jan 10, 2019 at 3:01 AM Martin Storsjö <martin at martin.st> wrote:

On Wed, 9 Jan 2019, David Greene wrote:

> I've come across a curious and pernicious problem in llvm-rc. > absolute.test checks that llvm-rc can accept a filename that is an > absolute path. And it works just fine. Until you run it with a file > that starts with "/c." Hmm, that's rather unfortunate indeed. FWIW, this test doesn't test specifically whether llvm-rc can accept an absolute filename as command line argument - all the llvm-rc tests run llvm-rc with absolute filenames as arguments. This test checks whether llvm-rc can handle an absolute filename reference within a rc file. I presume you run into the same issue on all other tests in test/tools/llvm-rc as well? > These will fail: > > llvm-rc /crawl/through/some/path/to/my.rc > llvm-rc /c/some/path/to/my.rc > > The option parser ends up interpreting "/" as an option prefix and then > the parser matches it to this in tools/llvm-rc/Opts.td: > > def CODEPAGE : JoinedOrSeparate<[ "/", "-" ], "C">, > HelpText<"Set the codepage used for input strings.">; > > The test then fails with: > Exactly one input file should be provided. > > The same problem happens with files that begin with "/r" > (/read/the/path/to/my.rc) "/sl" (/slink/along/the/path/to/my.rc) or any > other path that happens to begin with the same text as an option in > Opts.td. > > This triggered on one of our builders that just happens to build to a > path that begins with "/c." Presumably none of the existing Buildbots > build to paths that cause problems. > > It's easy enough to construct a test for this, but I'm not sure how/if > llvm-rc should be fixed. I don't know why it accepts both "/" and "-" > as option prefixes. As this mostly seems related to Windows (resource > files), should tests be UNSUPPORTED on every other platform? Or is > llvm-rc intended to be a cross-platform way to create resource files? It's definitely intended as a cross-platform tool for generating windows resource files, to allow for cross compilation etc. > If the latter, then it seems like options ought to use the "/" prefix on > Windows and "-" everywhere else so as not to conflict with path > specifiers. Well, build scripts that call llvm-rc might be using either (more or less agnostic of what platform it runs on). I personally prefer always using "-" everywhere though (which also is supported on windows, and also supported by the original microsoft tools, even if their help listings only display the form with a "/"). FWIW, lld-link also implements the same form of options using both prefixes, but there's less risk of unintended matches as most option names are full words, not single-char abbreviations. One way of disambiguating between option and pathname for the sake of the tests, would be to add '--' before the path arguments, which seems to be handled by the LLVM options parser at least. Does that sound sensible to you (and others CC:d)?

That sounds like the thing to do. It's also how we handle the same issue in clang-cl, where /Users/foo/file.c is interpreted as the /U (undefine macro) flag with"sers/foo/file.c" as argument instead of the intended macOS-style path.

clang-cl also has a dedicated warning for this ( http://reviews.llvm.org/rL293305), might be useful for some of llvm-rc's flags that are prone to this problem as well (/c, /r, maybe /sl)

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