r237304 - Break \# in a depfile the same way as gcc.

[Sean Silva]

Thanks.

-- Sean Silva

On Wed, May 13, 2015 at 3:33 PM, Paul Robinson <
paul_robinson at playstation.sony.com> wrote:

> Author: probinson
> Date: Wed May 13 17:33:50 2015
> New Revision: 237304
>
> URL: http://llvm.org/viewvc/llvm-project?rev=237304&view=rev
> Log:
> Break \# in a depfile the same way as gcc.
>
> Backslash followed by # in a filename should have both characters
> escaped, if you do it the way GNU Make wants.  GCC doesn't, so we do
> it the way GCC does rather than the way GNU Make wants.
>
> Modified:
>     cfe/trunk/lib/Frontend/DependencyFile.cpp
>     cfe/trunk/test/Frontend/dependency-gen-escaping.c
>
> Modified: cfe/trunk/lib/Frontend/DependencyFile.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Frontend/DependencyFile.cpp?rev=237304&r1=237303&r2=237304&view=diff
>
> ==============================================================================
> --- cfe/trunk/lib/Frontend/DependencyFile.cpp (original)
> +++ cfe/trunk/lib/Frontend/DependencyFile.cpp Wed May 13 17:33:50 2015
> @@ -310,37 +310,30 @@ void DFGImpl::AddFilename(StringRef File
>  /// retry with the unmodified original string.
>  ///
>  /// GCC tries to accommodate both Make formats by escaping any space or #
> -/// characters in the original filename, but not escaping any backslash
> -/// characters.  That way, filenames with backslashes will be handled
> +/// characters in the original filename, but not escaping backslashes.
> The
> +/// apparent intent is so that filenames with backslashes will be handled
>  /// correctly by BSD Make, and by GNU Make in its fallback mode of using
> the
>  /// unmodified original string; filenames with # or space characters
> aren't
>  /// supported by BSD Make at all, but will be handled correctly by GNU
> Make
>  /// due to the escaping.
>  ///
> -/// A corner case that GCC does not handle is when the original filename
> has
> -/// a backslash immediately followed by # or space. It will therefore
> take a
> -/// dependency from a directive such as
> -///     #include "a\#b.h"
> +/// A corner case that GCC gets only partly right is when the original
> filename
> +/// has a backslash immediately followed by space or #.  GNU Make would
> expect
> +/// this backslash to be escaped; however GCC escapes the original
> backslash
> +/// only when followed by space, not #.  It will therefore take a
> dependency
> +/// from a directive such as
> +///     #include "a\ b\#c.h"
>  /// and emit it as
> -///     a\\#b.h
> +///     a\\\ b\\#c.h
>  /// which GNU Make will interpret as
> -///     a\
> +///     a\ b\
>  /// followed by a comment. Failing to find this file, it will fall back
> to the
> -/// original string, and look for
> -///     a\\#b.h
> -/// which probably doesn't exist either; in any case it won't find
> -///     a\#b.h
> +/// original string, which probably doesn't exist either; in any case it
> won't
> +/// find
> +///     a\ b\#c.h
>  /// which is the actual filename specified by the include directive.
>  ///
> -/// Clang escapes space, # and $ like GCC does, but also handles the case
> of
> -/// backslash immediately preceding space or # by doubling those
> backslashes.
> -/// This means Clang will emit the dependency from
> -///     #include "a\#b.h"
> -/// as
> -///     a\\\#b.h
> -/// which GNU Make will un-escape into
> -///     a\#b.h
> -/// which is the correct original filename.
> +/// Clang does what GCC does, rather than what GNU Make expects.
>  ///
>  /// NMake/Jom has a different set of scary characters, but wraps
> filespecs in
>  /// double-quotes to avoid misinterpreting them; see
> @@ -359,8 +352,11 @@ static void PrintFilename(raw_ostream &O
>        OS << Filename;
>      return;
>    }
> +  assert(OutputFormat == DependencyOutputFormat::Make);
>    for (unsigned i = 0, e = Filename.size(); i != e; ++i) {
> -    if (Filename[i] == ' ' || Filename[i] == '#') {
> +    if (Filename[i] == '#') // Handle '#' the broken gcc way.
> +      OS << '\\';
> +    else if (Filename[i] == ' ') { // Handle space correctly.
>        OS << '\\';
>        unsigned j = i;
>        while (j > 0 && Filename[--j] == '\\')
>
> Modified: cfe/trunk/test/Frontend/dependency-gen-escaping.c
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Frontend/dependency-gen-escaping.c?rev=237304&r1=237303&r2=237304&view=diff
>
> ==============================================================================
> --- cfe/trunk/test/Frontend/dependency-gen-escaping.c (original)
> +++ cfe/trunk/test/Frontend/dependency-gen-escaping.c Wed May 13 17:33:50
> 2015
> @@ -17,9 +17,10 @@
>  #include "##.h"
>  #include "normal.h"
>
> -// Backslash followed by # or space is handled differently than GCC does,
> -// because GCC doesn't emit this obscure corner case the way GNU Make
> wants it.
> -// CHECK: a\b\\\#c\\\ d.h
> +// Backslash followed by # or space should escape both characters, because
> +// that's what GNU Make wants.  GCC does the right thing with space, but
> not
> +// #, so Clang does too. (There should be 3 backslashes before the #.)
> +// CHECK: a\b\\#c\\\ d.h
>  // These combinations are just another case for NMAKE.
>  // NMAKE: "a\b\#c\ d.h"
>
>
>
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