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 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." ? did you mean "e.g." ?

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
>