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

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.

Tested on x86_64-linux.

1 files changed, 109 insertions, 49 deletions

diff --git a/gdb/configure b/gdb/configure
index 6e2dfb7..fe685f2 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 for instance when using a source highlight
+      # library 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; }