build: osx: attempt to work with homebrew keg-only packages

Makefile.am

@@ -68,12 +68,13 @@ bench_sign_LDFLAGS = -static
 bench_inv_SOURCES = src/bench_inv.c
 bench_inv_LDADD = $(COMMON_LIB) $(SECP_LIBS)
 bench_inv_LDFLAGS = -static
+bench_inv_CPPFLAGS = $(SECP_INCLUDES)
 endif
 
 if USE_TESTS
 noinst_PROGRAMS += tests
 tests_SOURCES = src/tests.c
-tests_CPPFLAGS = -DVERIFY $(SECP_TEST_INCLUDES)
+tests_CPPFLAGS = -DVERIFY $(SECP_INCLUDES) $(SECP_TEST_INCLUDES)
 tests_LDADD = $(COMMON_LIB) $(SECP_LIBS) $(SECP_TEST_LIBS)
 tests_LDFLAGS = -static
 TESTS = tests

build-aux/m4/bitcoin_secp.m4

@@ -78,7 +78,13 @@ fi
 dnl
 AC_DEFUN([SECP_GMP_CHECK],[
 if test x"$has_gmp" != x"yes"; then
-  AC_CHECK_HEADER(gmp.h,[AC_CHECK_LIB(gmp, __gmpz_init,[has_gmp=yes; GMP_LIBS=-lgmp; AC_DEFINE(HAVE_LIBGMP,1,[Define this symbol if libgmp is installed])])])
+  CPPFLAGS_TEMP="$CPPFLAGS"
+  CPPFLAGS="$GMP_CPPFLAGS $CPPFLAGS"
+  LIBS_TEMP="$LIBS"
+  LIBS="$GMP_LIBS $LIBS"
+  AC_CHECK_HEADER(gmp.h,[AC_CHECK_LIB(gmp, __gmpz_init,[has_gmp=yes; GMP_LIBS="$GMP_LIBS -lgmp"; AC_DEFINE(HAVE_LIBGMP,1,[Define this symbol if libgmp is installed])])])
+  CPPFLAGS="$CPPFLAGS_TEMP"
+  LIBS="$LIBS_TEMP"
 fi
 if test x"$set_field" = x"gmp" && test x"$has_gmp" != x"yes"; then
     AC_MSG_ERROR([$set_field field support explicitly requested but libgmp was not found])

configure.ac

@@ -33,9 +33,34 @@ case $host in
 esac
 
 case $host_os in
-  darwin*)
+  *darwin*)
-     CPPFLAGS="$CPPFLAGS -I/opt/local/include"
+     if  test x$cross_compiling != xyes; then
+       AC_PATH_PROG([BREW],brew,)
+       if test x$BREW != x; then
+         dnl These Homebrew packages may be keg-only, meaning that they won't be found
+         dnl in expected paths because they may conflict with system files. Ask
+         dnl Homebrew where each one is located, then adjust paths accordingly.
+
+         openssl_prefix=`$BREW --prefix openssl 2>/dev/null`
+         gmp_prefix=`$BREW --prefix gmp 2>/dev/null`
+         if test x$openssl_prefix != x; then
+           PKG_CONFIG_PATH="$openssl_prefix/lib/pkgconfig:$PKG_CONFIG_PATH"
+           export PKG_CONFIG_PATH
+         fi
+         if test x$gmp_prefix != x; then
+           GMP_CPPFLAGS="-I$gmp_prefix/include"
+           GMP_LIBS="-L$gmp_prefix/lib"
+         fi
+       else
+         AC_PATH_PROG([PORT],port,)
+         dnl if homebrew isn't installed and macports is, add the macports default paths
+         dnl as a last resort.
+         if test x$PORT != x; then
+           CPPFLAGS="$CPPFLAGS -isystem /opt/local/include"
            LDFLAGS="$LDFLAGS -L/opt/local/lib"
+         fi
+       fi
+     fi
    ;;
 esac
 
@@ -236,6 +261,7 @@ fi
 
 if test x"$set_field" = x"gmp" || test x"$set_bignum" = x"gmp"; then
   SECP_LIBS="$SECP_LIBS $GMP_LIBS"
+  SECP_INCLUDES="$SECP_INCLUDES $GMP_CPPFLAGS"
 fi
 
 if test x"$use_endomorphism" = x"yes"; then
@@ -256,4 +282,10 @@ AC_SUBST(YASM_BINFMT)
 AM_CONDITIONAL([USE_ASM], [test x"$set_field" == x"64bit_asm"])
 AM_CONDITIONAL([USE_TESTS], [test x"$use_tests" != x"no"])
 AM_CONDITIONAL([USE_BENCHMARK], [test x"$use_benchmark" != x"no"])
+
+dnl make sure nothing new is exported so that we don't break the cache
+PKGCONFIG_PATH_TEMP="$PKG_CONFIG_PATH"
+unset PKG_CONFIG_PATH
+PKG_CONFIG_PATH="$PKGCONFIG_PATH_TEMP"
+
 AC_OUTPUT