[PATCH] Fix detection of compilation and linking flags for source-highlight

[PATCH] Fix detection of compilation and linking flags for source-highlight

[b7.10110111--- via Gdb-patches]

From: Ruslan Kabatsayev <b7.10110111@gmail.com>

Currently there are two problems with the detection via pkg-config:
1. LDFLAGS variable is used to pass --libs to AC_LINK_IFELSE, which
results in the "-L/some/path -lsource-highlight" preceding the
conftest.cpp, which results in failure to find symbol referenced in
conftest.cpp.
2. CFLAGS variable is used to compile C++ code instead of CXXFLAGS. This
results in --cflags not being passed to the compiler at all.

This patch fixes both of these mistakes, letting me get a working GDB
with source-highlight installed into a custom prefix ~/opt/gdb-git
(because system repos provide too old version).
---
 gdb/configure.ac | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/gdb/configure.ac b/gdb/configure.ac
index 5a380ce38d9..c6fa19b20bc 100644
--- a/gdb/configure.ac
+++ b/gdb/configure.ac
@@ -1242,10 +1242,10 @@ either use --disable-source-highlight or dnl
       # 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_LANG_PUSH(C++)
-      save_CFLAGS="$CFLAGS"
-      save_LDFLAGS="$LDFLAGS"
-      CFLAGS="$CFLAGS $srchigh_pkg_cflags"
-      LDFLAGS="$LDFLAGS $srchigh_pkg_libs"
+      save_CXXFLAGS="$CXXFLAGS"
+      save_LIBS="$LIBS"
+      CXXFLAGS="$CXXFLAGS $srchigh_pkg_cflags"
+      LIBS="$LIBS $srchigh_pkg_libs"
       AC_LINK_IFELSE(
         [AC_LANG_PROGRAM(
           [#include <srchilite/sourcehighlight.h>],
@@ -1255,8 +1255,8 @@ either use --disable-source-highlight or dnl
         [have_usable_source_highlight=yes],
         [have_usable_source_highlight=no]
       )
-      CFLAGS="$save_CFLAGS"
-      LDFLAGS="$save_LDFLAGS"
+      CXXFLAGS="$save_CXXFLAGS"
+      LIBS="$save_LIBS"
       AC_LANG_POP(C++)
 
       if test "${have_usable_source_highlight}" = "yes"; then
-- 
2.16.2

Re: [PATCH] Fix detection of compilation and linking flags for source-highlight

[Ruslan Kabatsayev via Gdb-patches]

Ping!

On Fri, 11 Feb 2022 at 20:10, <b7.10110111@gmail.com> wrote:
>
> From: Ruslan Kabatsayev <b7.10110111@gmail.com>
>
> Currently there are two problems with the detection via pkg-config:
> 1. LDFLAGS variable is used to pass --libs to AC_LINK_IFELSE, which
> results in the "-L/some/path -lsource-highlight" preceding the
> conftest.cpp, which results in failure to find symbol referenced in
> conftest.cpp.
> 2. CFLAGS variable is used to compile C++ code instead of CXXFLAGS. This
> results in --cflags not being passed to the compiler at all.
>
> This patch fixes both of these mistakes, letting me get a working GDB
> with source-highlight installed into a custom prefix ~/opt/gdb-git
> (because system repos provide too old version).
> ---
>  gdb/configure.ac | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/gdb/configure.ac b/gdb/configure.ac
> index 5a380ce38d9..c6fa19b20bc 100644
> --- a/gdb/configure.ac
> +++ b/gdb/configure.ac
> @@ -1242,10 +1242,10 @@ either use --disable-source-highlight or dnl
>        # 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_LANG_PUSH(C++)
> -      save_CFLAGS="$CFLAGS"
> -      save_LDFLAGS="$LDFLAGS"
> -      CFLAGS="$CFLAGS $srchigh_pkg_cflags"
> -      LDFLAGS="$LDFLAGS $srchigh_pkg_libs"
> +      save_CXXFLAGS="$CXXFLAGS"
> +      save_LIBS="$LIBS"
> +      CXXFLAGS="$CXXFLAGS $srchigh_pkg_cflags"
> +      LIBS="$LIBS $srchigh_pkg_libs"
>        AC_LINK_IFELSE(
>          [AC_LANG_PROGRAM(
>            [#include <srchilite/sourcehighlight.h>],
> @@ -1255,8 +1255,8 @@ either use --disable-source-highlight or dnl
>          [have_usable_source_highlight=yes],
>          [have_usable_source_highlight=no]
>        )
> -      CFLAGS="$save_CFLAGS"
> -      LDFLAGS="$save_LDFLAGS"
> +      CXXFLAGS="$save_CXXFLAGS"
> +      LIBS="$save_LIBS"
>        AC_LANG_POP(C++)
>
>        if test "${have_usable_source_highlight}" = "yes"; then
> --
> 2.16.2
>

Re: [PATCH] Fix detection of compilation and linking flags for source-highlight

[Andrew Burgess via Gdb-patches]

Ruslan Kabatsayev via Gdb-patches <gdb-patches@sourceware.org> writes:

> Ping!
>
> On Fri, 11 Feb 2022 at 20:10, <b7.10110111@gmail.com> wrote:
>>
>> From: Ruslan Kabatsayev <b7.10110111@gmail.com>
>>
>> Currently there are two problems with the detection via pkg-config:
>> 1. LDFLAGS variable is used to pass --libs to AC_LINK_IFELSE, which
>> results in the "-L/some/path -lsource-highlight" preceding the
>> conftest.cpp, which results in failure to find symbol referenced in
>> conftest.cpp.
>> 2. CFLAGS variable is used to compile C++ code instead of CXXFLAGS. This
>> results in --cflags not being passed to the compiler at all.
>>
>> This patch fixes both of these mistakes, letting me get a working GDB
>> with source-highlight installed into a custom prefix ~/opt/gdb-git
>> (because system repos provide too old version).
>> ---
>>  gdb/configure.ac | 12 ++++++------
>>  1 file changed, 6 insertions(+), 6 deletions(-)

Thanks for this.

I pushed the patch below.

Andrew

---

commit 6a8fe63330c922255a4ced4b6491d35f6c384bba
Author: Ruslan Kabatsayev <b7.10110111@gmail.com>
Date:   Fri Feb 11 20:10:23 2022 +0300

    gdb: fix detection of compilation and linking flags for source-highlight
    
    Currently there are two problems with the detection of
    source-highlight via pkg-config in GDB's configure script:
    
    1. The LDFLAGS variable is used to pass the 'pkg-config --libs' output
    to AC_LINK_IFELSE, which results in the "-L/some/path
    -lsource-highlight" preceding the conftest.cpp, which can result in a
    failure to find symbols referenced in conftest.cpp, if the linker is
    using --as-needed by default.
    
    2. The CFLAGS variable is used to pass the 'pkg-config --cflags'
    output to AC_LINK_IFELSE.  However, as the current language is C++,
    AC_LINK_IFELSE will actuall use CXXFLAGS, not CFLAGS, so any flags
    returned from pkg-config will not be seen.
    
    This patch fixes both of these mistakes, allowing GDB to correctly
    configure and build using source-highlight installed into a custom
    prefix, e.g. ~/opt/gdb-git (because the system version of
    source-highlight is too old).

diff --git a/gdb/configure b/gdb/configure
index e751edc3f9a..425bdb08a73 100755
--- a/gdb/configure
+++ b/gdb/configure
@@ -12148,10 +12148,10 @@ 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 $srchigh_pkg_libs"
+      save_CXXFLAGS="$CXXFLAGS"
+      save_LIBS="$LIBS"
+      CXXFLAGS="$CXXFLAGS $srchigh_pkg_cflags"
+      LIBS="$LIBS $srchigh_pkg_libs"
       cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 #include <srchilite/sourcehighlight.h>
@@ -12173,8 +12173,8 @@ else
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
-      CFLAGS="$save_CFLAGS"
-      LDFLAGS="$save_LDFLAGS"
+      CXXFLAGS="$save_CXXFLAGS"
+      LIBS="$save_LIBS"
       ac_ext=c
 ac_cpp='$CPP $CPPFLAGS'
 ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
diff --git a/gdb/configure.ac b/gdb/configure.ac
index 5a380ce38d9..c6fa19b20bc 100644
--- a/gdb/configure.ac
+++ b/gdb/configure.ac
@@ -1242,10 +1242,10 @@ either use --disable-source-highlight or dnl
       # 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_LANG_PUSH(C++)
-      save_CFLAGS="$CFLAGS"
-      save_LDFLAGS="$LDFLAGS"
-      CFLAGS="$CFLAGS $srchigh_pkg_cflags"
-      LDFLAGS="$LDFLAGS $srchigh_pkg_libs"
+      save_CXXFLAGS="$CXXFLAGS"
+      save_LIBS="$LIBS"
+      CXXFLAGS="$CXXFLAGS $srchigh_pkg_cflags"
+      LIBS="$LIBS $srchigh_pkg_libs"
       AC_LINK_IFELSE(
         [AC_LANG_PROGRAM(
           [#include <srchilite/sourcehighlight.h>],
@@ -1255,8 +1255,8 @@ either use --disable-source-highlight or dnl
         [have_usable_source_highlight=yes],
         [have_usable_source_highlight=no]
       )
-      CFLAGS="$save_CFLAGS"
-      LDFLAGS="$save_LDFLAGS"
+      CXXFLAGS="$save_CXXFLAGS"
+      LIBS="$save_LIBS"
       AC_LANG_POP(C++)
 
       if test "${have_usable_source_highlight}" = "yes"; then