build: Use pkg-config to find FreeType

pkg-config is apparently preferred over freetype-config these days (see
the BUGS section of freetype-config(1)).  pkg-config support was added
to FreeType in version 2.1.5, which was released in 2003, so it should
comfortably be available everywhere by now.

We no longer need to explicitly substitute FREETYPE_CFLAGS and
FREETYPE_LIBS, since PKG_CHECK_MODULES does that automatically.

Fixes Debian bug #887721.

Reported-by: Hugh McMaster <hugh.mcmaster@outlook.com>
Signed-off-by: Colin Watson <cjwatson@ubuntu.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

INSTALL

@@ -37,6 +37,7 @@ configuring the GRUB.
 * GNU gettext 0.17 or later
 * GNU binutils 2.9.1.0.23 or later
 * Flex 2.5.35 or later
+* pkg-config
 * Other standard GNU/Unix tools
 * a libc with large file support (e.g. glibc 2.1 or later)
 
@@ -52,7 +53,7 @@ For optional grub-emu features, you need:
 
 To build GRUB's graphical terminal (gfxterm), you need:
 
-* FreeType 2 or later
+* FreeType 2.1.5 or later
 * GNU Unifont
 
 If you use a development snapshot or want to hack on GRUB you may
@@ -158,8 +159,8 @@ For this example the configure line might look like (more details below)
 (some options are optional and included here for completeness but some rarely
 used options are omitted):
 
-./configure BUILD_CC=gcc BUILD_FREETYPE=freetype-config --host=amd64-linux-gnu
-CC=amd64-linux-gnu-gcc CFLAGS="-g -O2" FREETYPE=amd64-linux-gnu-freetype-config
+./configure BUILD_CC=gcc BUILD_PKG_CONFIG=pkg-config --host=amd64-linux-gnu
+CC=amd64-linux-gnu-gcc CFLAGS="-g -O2" PKG_CONFIG=amd64-linux-gnu-pkg-config
 --target=arm --with-platform=uboot TARGET_CC=arm-elf-gcc
 TARGET_CFLAGS="-Os -march=armv6" TARGET_CCASFLAGS="-march=armv6"
 TARGET_OBJCOPY="arm-elf-objcopy" TARGET_STRIP="arm-elf-strip"
@@ -176,7 +177,7 @@ corresponding platform are not needed for the platform in question.
     2. BUILD_CFLAGS= for C options for build.
     3. BUILD_CPPFLAGS= for C preprocessor options for build.
     4. BUILD_LDFLAGS= for linker options for build.
-    5. BUILD_FREETYPE= for freetype-config for build (optional).
+    5. BUILD_PKG_CONFIG= for pkg-config for build (optional).
 
   - For host
     1. --host= to autoconf name of host.
@@ -184,7 +185,7 @@ corresponding platform are not needed for the platform in question.
     3. HOST_CFLAGS= for C options for host.
     4. HOST_CPPFLAGS= for C preprocessor options for host.
     5. HOST_LDFLAGS= for linker options for host.
-    6. FREETYPE= for freetype-config for host (optional).
+    6. PKG_CONFIG= for pkg-config for host (optional).
     7. Libdevmapper if any must be in standard linker folders (-ldevmapper) (optional).
     8. Libfuse if any must be in standard linker folders (-lfuse) (optional).
     9. Libzfs if any must be in standard linker folders (-lzfs) (optional).

configure.ac

@@ -50,6 +50,10 @@ AC_PREREQ(2.60)
 AC_CONFIG_SRCDIR([include/grub/dl.h])
 AC_CONFIG_HEADER([config-util.h])
 
+# Explicitly check for pkg-config early on, since otherwise conditional
+# calls are problematic.
+PKG_PROG_PKG_CONFIG
+
 # Program name transformations
 AC_ARG_PROGRAM
 grub_TRANSFORM([grub-bios-setup])
@@ -1508,29 +1512,22 @@ if test x"$enable_grub_mkfont" = xno ; then
   grub_mkfont_excuse="explicitly disabled"
 fi
 
-if test x"$grub_mkfont_excuse" = x ; then
-  # Check for freetype libraries.
-  AC_CHECK_TOOLS([FREETYPE], [freetype-config])
-  if test "x$FREETYPE" = x ; then
-    grub_mkfont_excuse=["need freetype2 library"]
-  fi
-fi
-
 unset ac_cv_header_ft2build_h
 
 if test x"$grub_mkfont_excuse" = x ; then
   # Check for freetype libraries.
-  FREETYPE_CFLAGS=`$FREETYPE --cflags`
-  FREETYPE_LIBS=`$FREETYPE --libs`
+  PKG_CHECK_MODULES([FREETYPE], [freetype2], [
     SAVED_CPPFLAGS="$CPPFLAGS"
     SAVED_LIBS="$LIBS"
     CPPFLAGS="$CPPFLAGS $FREETYPE_CFLAGS"
     LIBS="$LIBS $FREETYPE_LIBS"
     AC_CHECK_HEADERS([ft2build.h], [],
       [grub_mkfont_excuse=["need freetype2 headers"]])
-  AC_LINK_IFELSE([AC_LANG_CALL([], [FT_Load_Glyph])], [], [grub_mkfont_excuse=["freetype2 library unusable"]])
+    AC_LINK_IFELSE([AC_LANG_CALL([], [FT_Load_Glyph])], [],
+      [grub_mkfont_excuse=["freetype2 library unusable"]])
     CPPFLAGS="$SAVED_CPPFLAGS"
     LIBS="$SAVED_LIBS"
+  ], [grub_mkfont_excuse=["need freetype2 library"]])
 fi
 
 if test x"$enable_grub_mkfont" = xyes && test x"$grub_mkfont_excuse" != x ; then
@@ -1542,8 +1539,6 @@ else
 enable_grub_mkfont=no
 fi
 AC_SUBST([enable_grub_mkfont])
-AC_SUBST([FREETYPE_CFLAGS])
-AC_SUBST([FREETYPE_LIBS])
 
 SAVED_CC="$CC"
 SAVED_CPP="$CPP"
@@ -1573,25 +1568,21 @@ AC_SUBST([BUILD_WORDS_BIGENDIAN])
 
 if test x"$grub_build_mkfont_excuse" = x ; then
   # Check for freetype libraries.
-  AC_CHECK_PROGS([BUILD_FREETYPE], [freetype-config])
-  if test "x$BUILD_FREETYPE" = x ; then
-    grub_build_mkfont_excuse=["need freetype2 library"]
-  fi
-fi
-
-if test x"$grub_build_mkfont_excuse" = x ; then
-  # Check for freetype libraries.
-  BUILD_FREETYPE_CFLAGS=`$BUILD_FREETYPE --cflags`
-  BUILD_FREETYPE_LIBS=`$BUILD_FREETYPE --libs`
+  SAVED_PKG_CONFIG="$PKG_CONFIG"
+  test -z "$BUILD_PKG_CONFIG" || PKG_CONFIG="$BUILD_PKG_CONFIG"
+  PKG_CHECK_MODULES([BUILD_FREETYPE], [freetype2], [
     SAVED_CPPFLAGS_2="$CPPFLAGS"
     SAVED_LIBS="$LIBS"
     CPPFLAGS="$CPPFLAGS $BUILD_FREETYPE_CFLAGS"
     LIBS="$LIBS $BUILD_FREETYPE_LIBS"
     AC_CHECK_HEADERS([ft2build.h], [],
       [grub_build_mkfont_excuse=["need freetype2 headers"]])
-  AC_LINK_IFELSE([AC_LANG_CALL([], [FT_Load_Glyph])], [], [grub_build_mkfont_excuse=["freetype2 library unusable"]])
+    AC_LINK_IFELSE([AC_LANG_CALL([], [FT_Load_Glyph])], [],
+      [grub_build_mkfont_excuse=["freetype2 library unusable"]])
     LIBS="$SAVED_LIBS"
     CPPFLAGS="$SAVED_CPPFLAGS_2"
+  ], [grub_build_mkfont_excuse=["need freetype2 library"]])
+  PKG_CONFIG="$SAVED_PKG_CONFIG"
 fi
 
 if test x"$enable_build_grub_mkfont" = xyes && test x"$grub_build_mkfont_excuse" != x ; then
@@ -1610,9 +1601,6 @@ if test x"$enable_build_grub_mkfont" = xno && ( test "x$platform" = xqemu || tes
   fi
 fi
 
-AC_SUBST([BUILD_FREETYPE_CFLAGS])
-AC_SUBST([BUILD_FREETYPE_LIBS])
-
 CC="$SAVED_CC"
 CPP="$SAVED_CPP"
 CFLAGS="$SAVED_CFLAGS"