Re: [PATCH] Support more C++ extensions for MSVC in the compile script.

[Ralf Wildenhues]

Hi Peter,

* Peter Rosin wrote on Fri, Aug 13, 2010 at 03:37:59PM CEST:
> This is one of the last bits of functionality from the (dwindling)
> pr-msvc-support branch in Libtool (the remaining bit is triggering
> the ar-lib script with a new macro and some things related to that).

Cool.

> MSVC only recognizes .c and .cpp as source files, if you say e.g.
> foo.cc, it will treat it as an object file. Many projects do not use
> .cpp for its C++ files, so this patch will make it work for a bunch
> of more projects.
> 
> I have not added .C to the list of C++ extensions as Windows typically
> has a case insensitive file system, and then you don't know if the
> user meant C or C++...

Good point.  Users will have to cope anyway.

> Ok for the msvc branch?

Ok with nits below addressed.  Thanks!
Ralf

> +2010-08-13  Peter Rosin  <address@hidden>
> +
> +     Support more C++ extensions for MSVC in the compile script.

s/extensions/file &/  ?  IMHO that would make it a bit clearer.

> +     * lib/compile (func_cl_wrapper): MSVC only recognizes the .cpp
> +     extension as C++, unless it's given a hint. So hint about
> +     .cc, .cxx, c++ and C++. Also do path conversion on .c, .cpp
> +     and .lib files.

See below for a question about this.

> +     * lib/compile3.test: Test the C++ hinting.

> --- a/lib/compile
> +++ b/lib/compile

> @@ -129,6 +129,16 @@ func_cl_wrapper ()
>         eat=1
>         linker_opts="$linker_opts $2"
>         ;;

Please add a case
        -*)
          set x "$@" "$1"
          shift
          ;;

here and simplify the following matches accordingly.

> +     [!-]*.cc | [!-]*.cxx | [!-]*.[cC]++)

What about *.CC and *.CXX?

> +       func_file_conv "$1"
> +       set x "$@" -Tp"$file"
> +       shift
> +       ;;
> +     [!-]*.c | [!-]*.cpp | [!-]*.lib | [!-]*.LIB | [!-]*.Lib)
> +       func_file_conv "$1"

What about *.CPP?

Why do you convert here?  Seems to me that since the files stand alone,
MSYS conversion would kick in, no?  If this is about conversion on
non-MSYS systems, please state so in the log entry.  Thanks.

Actually, there is an efficiency question in there: we know when exactly
name conversion happens on MSYS, namely when the name is a positional
parameter on its own (and in a couple of other cases which I have all
but forgotten again).  In those cases, we could avoid doing manual
conversion, thereby avoiding extra forks.

One way this could be implemented would be to pass an extra argument $2
to func_file_conv that could be empty or "-lazy" or so, and in the
function match against $file_conv$2 with cygwin-lazy same as cygwin but
mingw-lazy a nop.

If you think this is worthwhile, then I would accept such a change in a
later patch, given some numbers that show an actual improvement.  I can
also write the patch if you do the measurement.  (Trying to stick to the
"no optimization without measurement" principle.)

> +       set x "$@" "$file"
> +       shift
> +       ;;
>       *)
>         set x "$@" "$1"
>         shift