Re: linking a shared library with -pthread omits -pthread on the link line.

[Albert Chin]

On Sat, Dec 14, 2002 at 05:26:22PM -0000, Max Bowsher wrote:
> Howard Chu <address@hidden> wrote:
> 
> >> I'm trying to use CC="gcc -mno-cygwin" CXX="gcc -mno-cygwin",
> >> obviously
> >> expecting that the -mno-cygwin is appended to *every*
> >> invocation of gcc.
> >> Now, this works for CXX (The variable CC in the tagged config
> >> CXX gets the
> >> value from the environment. In addition, LTCC gets the value
> >> of CC from the
> >> environment in every tag. *But* CC in the untagged C config drops
> >> the -mno-cygwin.
> >>
> >> I kludged it by doing this to libtool.m4:
> >> @@ -2295,6 +2296,9 @@
> >>
> >>  _LT_AC_SYS_COMPILER
> >>
> >> +# Allow CC to be a program name with arguments.
> >> +_LT_AC_TAGVAR(compiler, $1)="$CC"
> >> +
> >>  #
> >>  # Check for any special shared library compilation flags.
> >>  #
> >>
> >> But that was more by random guess than a through understanding of the
> >> implications of my change.
> >
> > This is also something we reported 2 or 3 years ago and finally gave
> > up on. We went with suggesting that people just create a wrapper
> > shell script for gcc that carries the correct options:
> >
> > http://www.openldap.org/faq/data/cache/301.html
> >
> > At the bottom of the page...
> > ( mgcc:
> > #! /bin/sh
> > gcc -mno-cygwin $*
> > )
> 
> Wait a minute! It *works* for CXX, so why can't it be made to work for CC as
> well?

Because it's different! Actually, it works for everything *except* the
C tag. The reason is because we do this:
  set dummy $CC
  compiler=$2

Obviously, if CC="gcc -mno-cygwin", then $2=gcc. The correct solution
is:
  set dummy "$CC"
  compiler=$2

Now, all non-C tags do:
  # ltmain only uses $CC for tagged configurations so make sure $CC is set.
  _LT_AC_SYS_COMPILER

  # Allow CC to be a program name with arguments.
  lt_save_CC="$CC"
  CC=${CXX-"c++"}
  set dummy $CC
  compiler="[$]2"
  _LT_AC_TAGVAR(compiler, $1)=$CC
  cc_basename=`$echo X"$compiler" | $Xsed -e 's%^.*/%%'`
The reason it works for non-C tags is the overriding of $compiler
with:
  _LT_AC_TAGVAR(compiler, $1)=$CC

What's the advantage of:
  set dummy "$CC"
  compiler=$2
to:
  compiler=$CC

The latter is essentially what the non-C tags are doing. So, I
recommend the patch below.

-- 
albert chin (address@hidden)

-- snip snip
2002-12-14  Albert Chin-A-Young (address@hidden)

        * libtool.m4: Correctly set $CC in libtool. Previously
        used:
          set dummy $CC
          compiler="[$]2"
        but if CC contains a program name with arguments, then
        CC will be the program name only. Rather than:
          set dummy "$CC"
          compiler="[$]2"
        we just:
          compiler=$CC

Index: libtool.m4
===================================================================
RCS file: /cvsroot/libtool/libtool/libtool.m4,v
retrieving revision 1.280
diff -u -3 -p -r1.280 libtool.m4
--- libtool.m4  11 Dec 2002 19:44:59 -0000      1.280
+++ libtool.m4  14 Dec 2002 20:10:30 -0000
@@ -241,8 +241,7 @@ AC_DEFUN([_LT_AC_SYS_COMPILER],
 LTCC=${LTCC-"$CC"}
 
 # Allow CC to be a program name with arguments.
-set dummy $CC
-compiler="[$]2"
+compiler=$CC
 ])# _LT_AC_SYS_COMPILER
 
 
@@ -2507,8 +2526,7 @@ _LT_AC_SYS_COMPILER
 # Allow CC to be a program name with arguments.
 lt_save_CC="$CC"
 CC=${CXX-"c++"}
-set dummy $CC
-compiler="[$]2"
+compiler=$CC
 _LT_AC_TAGVAR(compiler, $1)=$CC
 cc_basename=`$echo X"$compiler" | $Xsed -e 's%^.*/%%'`
 
@@ -3399,8 +3451,7 @@ _LT_AC_SYS_COMPILER
 # Allow CC to be a program name with arguments.
 lt_save_CC="$CC"
 CC=${F77-"f77"}
-set dummy $CC
-compiler="[$]2"
+compiler=$CC
 _LT_AC_TAGVAR(compiler, $1)=$CC
 cc_basename=`$echo X"$compiler" | $Xsed -e 's%^.*/%%'`
 
@@ -3479,8 +3530,7 @@ _LT_AC_SYS_COMPILER
 # Allow CC to be a program name with arguments.
 lt_save_CC="$CC"
 CC=${GCJ-"gcj"}
-set dummy $CC
-compiler="[$]2"
+compiler=$CC
 _LT_AC_TAGVAR(compiler, $1)=$CC
 
 # GCJ did not exist at the time GCC didn't implicitly link libc in.
@@ -3535,8 +3585,7 @@ _LT_AC_SYS_COMPILER
 # Allow CC to be a program name with arguments.
 lt_save_CC="$CC"
 CC=${RC-"windres"}
-set dummy $CC
-compiler="[$]2"
+compiler=$CC
 _LT_AC_TAGVAR(compiler, $1)=$CC
 _LT_AC_TAGVAR(lt_cv_prog_compiler_c_o, $1)=yes