Re: [PATCH] [gdb/build] Check if libsource-highlight is usable

[Andrew Burgess <aburgess@redhat.com>]

* Tom de Vries via Gdb-patches <gdb-patches@sourceware.org> [2021-11-19 21:56:41 +0100]:

> On 11/19/21 4:56 PM, Andrew Burgess wrote:
> > * Tom de Vries via Gdb-patches <gdb-patches@sourceware.org> [2021-11-19 13:34:23 +0100]:
> > 
> >> When building gdb with g++ 4.8.5, I ran into:
> >> ...
> >> ld: source-cache.o: in function `source_cache::ensure(symtab*)':
> >> source-cache.c:207: undefined reference to \
> >>   srchilite::SourceHighlight::SourceHighlight(std::string const&)
> >> ...
> >>
> >> [ I configured gdb without explicit settings related to source-highlight, so
> >> we're excercising the enable_source_highlight=auto scenario. ]
> >>
> >> The problem is that:
> >> - the source-highlight library is build with system compiler
> >>   g++ 7.5.0 which uses the new libstdc++ library abi (see
> >>   https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_dual_abi.html )
> >> - gdb is build using g++ 4.8.5 which uses the old abi.
> >>
> >> [ There's a compatibility macro _GLIBCXX_USE_CXX11_ABI, but that doesn't work
> >> for this case.  Instead, it enables the opposite case where the
> >> source-highlight library is build with g++ 4.8.5 and gdb is build with
> >> g++ 7.5.0. ]
> >>
> >> Fix this by checking whether the source-highlight library is usable during
> >> configuration.
> >>
> >> In the enable_source_highlight=auto scenario, this allows the build to skip
> >> the unusable library and finish successfully.
> >>
> >> In the enable_source_highlight=yes scenario, this allows the build to error
> >> out earlier.
> > 
> > I make no claims of being an autoconf expert, but this all looks
> > reasonable to me.  I had just one tiny nit..
> > 
> >>
> >> Tested on x86_64-linux.
> >> ---
> >>  gdb/configure    | 158 ++++++++++++++++++++++++++++++++---------------
> >>  gdb/configure.ac |  47 ++++++++++++--
> >>  2 files changed, 151 insertions(+), 54 deletions(-)
> >>
> >> diff --git a/gdb/configure b/gdb/configure
> >> index 6e2dfb766c8..aaa622d9fcc 100755
> >> --- a/gdb/configure
> >> +++ b/gdb/configure
> >> @@ -2367,6 +2367,52 @@ $as_echo "$ac_res" >&6; }
> >>  
> >>  } # ac_fn_c_check_func
> >>  
> >> +# ac_fn_cxx_try_link LINENO
> >> +# -------------------------
> >> +# Try to link conftest.$ac_ext, and return whether this succeeded.
> >> +ac_fn_cxx_try_link ()
> >> +{
> >> +  as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
> >> +  rm -f conftest.$ac_objext conftest$ac_exeext
> >> +  if { { ac_try="$ac_link"
> >> +case "(($ac_try" in
> >> +  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
> >> +  *) ac_try_echo=$ac_try;;
> >> +esac
> >> +eval ac_try_echo="\"\$as_me:${as_lineno-$LINENO}: $ac_try_echo\""
> >> +$as_echo "$ac_try_echo"; } >&5
> >> +  (eval "$ac_link") 2>conftest.err
> >> +  ac_status=$?
> >> +  if test -s conftest.err; then
> >> +    grep -v '^ *+' conftest.err >conftest.er1
> >> +    cat conftest.er1 >&5
> >> +    mv -f conftest.er1 conftest.err
> >> +  fi
> >> +  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
> >> +  test $ac_status = 0; } && {
> >> +	 test -z "$ac_cxx_werror_flag" ||
> >> +	 test ! -s conftest.err
> >> +       } && test -s conftest$ac_exeext && {
> >> +	 test "$cross_compiling" = yes ||
> >> +	 test -x conftest$ac_exeext
> >> +       }; then :
> >> +  ac_retval=0
> >> +else
> >> +  $as_echo "$as_me: failed program was:" >&5
> >> +sed 's/^/| /' conftest.$ac_ext >&5
> >> +
> >> +	ac_retval=1
> >> +fi
> >> +  # Delete the IPA/IPO (Inter Procedural Analysis/Optimization) information
> >> +  # created by the PGI compiler (conftest_ipa8_conftest.oo), as it would
> >> +  # interfere with the next link command; also delete a directory that is
> >> +  # left behind by Apple's compiler.  We do this before executing the actions.
> >> +  rm -rf conftest.dSYM conftest_ipa8_conftest.oo
> >> +  eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
> >> +  as_fn_set_status $ac_retval
> >> +
> >> +} # ac_fn_cxx_try_link
> >> +
> >>  # ac_fn_c_check_type LINENO TYPE VAR INCLUDES
> >>  # -------------------------------------------
> >>  # Tests whether TYPE exists after having included INCLUDES, setting cache
> >> @@ -2524,52 +2570,6 @@ $as_echo "$ac_res" >&6; }
> >>  
> >>  } # ac_fn_c_check_member
> >>  
> >> -# ac_fn_cxx_try_link LINENO
> >> -# -------------------------
> >> -# Try to link conftest.$ac_ext, and return whether this succeeded.
> >> -ac_fn_cxx_try_link ()
> >> -{
> >> -  as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
> >> -  rm -f conftest.$ac_objext conftest$ac_exeext
> >> -  if { { ac_try="$ac_link"
> >> -case "(($ac_try" in
> >> -  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
> >> -  *) ac_try_echo=$ac_try;;
> >> -esac
> >> -eval ac_try_echo="\"\$as_me:${as_lineno-$LINENO}: $ac_try_echo\""
> >> -$as_echo "$ac_try_echo"; } >&5
> >> -  (eval "$ac_link") 2>conftest.err
> >> -  ac_status=$?
> >> -  if test -s conftest.err; then
> >> -    grep -v '^ *+' conftest.err >conftest.er1
> >> -    cat conftest.er1 >&5
> >> -    mv -f conftest.er1 conftest.err
> >> -  fi
> >> -  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
> >> -  test $ac_status = 0; } && {
> >> -	 test -z "$ac_cxx_werror_flag" ||
> >> -	 test ! -s conftest.err
> >> -       } && test -s conftest$ac_exeext && {
> >> -	 test "$cross_compiling" = yes ||
> >> -	 test -x conftest$ac_exeext
> >> -       }; then :
> >> -  ac_retval=0
> >> -else
> >> -  $as_echo "$as_me: failed program was:" >&5
> >> -sed 's/^/| /' conftest.$ac_ext >&5
> >> -
> >> -	ac_retval=1
> >> -fi
> >> -  # Delete the IPA/IPO (Inter Procedural Analysis/Optimization) information
> >> -  # created by the PGI compiler (conftest_ipa8_conftest.oo), as it would
> >> -  # interfere with the next link command; also delete a directory that is
> >> -  # left behind by Apple's compiler.  We do this before executing the actions.
> >> -  rm -rf conftest.dSYM conftest_ipa8_conftest.oo
> >> -  eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
> >> -  as_fn_set_status $ac_retval
> >> -
> >> -} # ac_fn_cxx_try_link
> >> -
> >>  # ac_fn_cxx_check_func LINENO FUNC VAR
> >>  # ------------------------------------
> >>  # Tests whether FUNC exists, setting the cache variable VAR accordingly
> >> @@ -12103,13 +12103,73 @@ $as_echo "no - pkg-config not found" >&6; }
> >>            ;;
> >>        esac
> >>  
> >> -      SRCHIGH_CFLAGS=`${pkg_config_prog_path} --cflags source-highlight`
> >> -      SRCHIGH_LIBS=`${pkg_config_prog_path} --libs source-highlight`
> >> +      srchigh_pkg_cflags=`${pkg_config_prog_path} --cflags source-highlight`
> >> +      srchigh_pkg_libs=`${pkg_config_prog_path} --libs source-highlight`
> >> +
> >> +      # Now that we have found a source-highlight library, check if we can use
> >> +      # it.  In particular, we're trying to detect the situation that the
> >> +      # library is using the new libstdc++ library abi ( see
> >> +      # https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_dual_abi.html )
> >> +      # while the compiler being used to compile gdb is using the old abi.
> >> +      # Such a situation will result in an undefined reference to
> >> +      # srchilite::SourceHighlight::SourceHighlight(std::string const&).
> >> +      # This situation can occur when f.i. using a source highlight library
> > 
> > what's "f.i." ? 
> 
> For instance.

OK, that makes sense.

> 
> >did you mean "e.g." ?
> 
> Well, I meant for instance.  That is, I know "e.g.", but I find it hard
> to use because it doesn't directly map to an english language
> expression, like "f.i.".  So I'd prefer to continue to use this, unless
> it's hard to understand for people in general.  I'm
> not-a-native-speaker, so feedback on that is welcome :)

I've never seen "for instance" abbreviated to "f.i." before, so, I'd
just suggest saying "for instance".

Or don't change it at all if you don't want to :)  I was still able to
understand what you were saying, so it's not really important.

Thanks,
Andrew


> 
> Thanks,
> - Tom
> 
> > 
> > Otherwise, LGTM.
> > 
> > Thanks,
> > Andrew
> > 
> >> +      # compiled with g++ 7.5.0 while building gdb with g++ 4.8.5.
> >> +      ac_ext=cpp
> >> +ac_cpp='$CXXCPP $CPPFLAGS'
> >> +ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
> >> +ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
> >> +ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
> >> +
> >> +      save_CFLAGS=$CFLAGS
> >> +      save_LDFLAGS=$LDFLAGS
> >> +      CFLAGS="$CFLAGS $srchigh_pkg_cflags"
> >> +      LDFLAGS="$LDFLAGS $srchigh_pkg_libs"
> >> +      cat confdefs.h - <<_ACEOF >conftest.$ac_ext
> >> +/* end confdefs.h.  */
> >> +#include <srchilite/sourcehighlight.h>
> >> +int
> >> +main ()
> >> +{
> >> +std::string outlang = "esc.outlang";
> >> +           new srchilite::SourceHighlight (outlang);
> >> +
> >> +  ;
> >> +  return 0;
> >> +}
> >> +_ACEOF
> >> +if ac_fn_cxx_try_link "$LINENO"; then :
> >> +  have_usable_source_highlight=yes
> >> +else
> >> +  have_usable_source_highlight=no
> >> +
> >> +fi
> >> +rm -f core conftest.err conftest.$ac_objext \
> >> +    conftest$ac_exeext conftest.$ac_ext
> >> +      CFLAGS="$SAVE_CFLAGS"
> >> +      LDFLAGS="$SAVE_LDFLAGS"
> >> +      ac_ext=c
> >> +ac_cpp='$CPP $CPPFLAGS'
> >> +ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
> >> +ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
> >> +ac_compiler_gnu=$ac_cv_c_compiler_gnu
> >> +
> >> +
> >> +      if test "${have_usable_source_highlight}" = "yes"; then
> >>  
> >>  $as_echo "#define HAVE_SOURCE_HIGHLIGHT 1" >>confdefs.h
> >>  
> >> -      { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
> >> +        { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
> >>  $as_echo "yes" >&6; }
> >> +        SRCHIGH_CFLAGS="$srchigh_pkg_cflags"
> >> +        SRCHIGH_LIBS="$srchigh_pkg_libs"
> >> +      else
> >> +	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
> >> +$as_echo "no" >&6; }
> >> +	if test "${enable_source_highlight}" = "yes"; then
> >> +          as_fn_error $? "source-highlight in your system could not be used" "$LINENO" 5
> >> +        fi
> >> +      fi
> >>      else
> >>        { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
> >>  $as_echo "no" >&6; }
> >> diff --git a/gdb/configure.ac b/gdb/configure.ac
> >> index d4cfb6a7624..e4fed3c575c 100644
> >> --- a/gdb/configure.ac
> >> +++ b/gdb/configure.ac
> >> @@ -1248,11 +1248,48 @@ either use --disable-source-highlight or dnl
> >>            ;;
> >>        esac
> >>  
> >> -      SRCHIGH_CFLAGS=`${pkg_config_prog_path} --cflags source-highlight`
> >> -      SRCHIGH_LIBS=`${pkg_config_prog_path} --libs source-highlight`
> >> -      AC_DEFINE([HAVE_SOURCE_HIGHLIGHT], 1,
> >> -                [Define to 1 if the source-highlight library is available])
> >> -      AC_MSG_RESULT([yes])
> >> +      srchigh_pkg_cflags=`${pkg_config_prog_path} --cflags source-highlight`
> >> +      srchigh_pkg_libs=`${pkg_config_prog_path} --libs source-highlight`
> >> +
> >> +      # Now that we have found a source-highlight library, check if we can use
> >> +      # it.  In particular, we're trying to detect the situation that the
> >> +      # library is using the new libstdc++ library abi ( see
> >> +      # https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_dual_abi.html )
> >> +      # while the compiler being used to compile gdb is using the old abi.
> >> +      # Such a situation will result in an undefined reference to
> >> +      # srchilite::SourceHighlight::SourceHighlight(std::string const&).
> >> +      # This situation can occur when f.i. using a source highlight library
> >> +      # compiled with g++ 7.5.0 while building gdb with g++ 4.8.5.
> >> +      AC_LANG_PUSH(C++)
> >> +      save_CFLAGS=$CFLAGS
> >> +      save_LDFLAGS=$LDFLAGS
> >> +      CFLAGS="$CFLAGS $srchigh_pkg_cflags"
> >> +      LDFLAGS="$LDFLAGS $srchigh_pkg_libs"
> >> +      AC_LINK_IFELSE(
> >> +        [AC_LANG_PROGRAM(
> >> +          [#include <srchilite/sourcehighlight.h>],
> >> +          [std::string outlang = "esc.outlang";
> >> +           new srchilite::SourceHighlight (outlang);]
> >> +        )],
> >> +        [have_usable_source_highlight=yes],
> >> +        [have_usable_source_highlight=no]
> >> +      )
> >> +      CFLAGS="$SAVE_CFLAGS"
> >> +      LDFLAGS="$SAVE_LDFLAGS"
> >> +      AC_LANG_POP(C++)
> >> +
> >> +      if test "${have_usable_source_highlight}" = "yes"; then
> >> +        AC_DEFINE([HAVE_SOURCE_HIGHLIGHT], 1,
> >> +                  [Define to 1 if the source-highlight library is available])
> >> +        AC_MSG_RESULT([yes])
> >> +        SRCHIGH_CFLAGS="$srchigh_pkg_cflags"
> >> +        SRCHIGH_LIBS="$srchigh_pkg_libs"
> >> +      else
> >> +	AC_MSG_RESULT([no])
> >> +	if test "${enable_source_highlight}" = "yes"; then
> >> +          AC_MSG_ERROR([source-highlight in your system could not be used])
> >> +        fi
> >> +      fi
> >>      else
> >>        AC_MSG_RESULT([no])
> >>        if test "${enable_source_highlight}" = "yes"; then
> >>
> >> base-commit: fd0ff19bf435b267caae6a1ae04e7b4a4ba64f5b
> >> -- 
> >> 2.26.2
> >>
> >