From 5d66a0ce39f47b7b9f6c732a18ac6e102a21ee6b Mon Sep 17 00:00:00 2001
From: Ben Gamari <ben@smart-cactus.org>
Date: Sun, 7 Aug 2022 19:28:20 -0400
Subject: system-cxx-std-lib: Add support for FreeBSD libcxxrt

---
 m4/fp_find_cxx_std_lib.m4 | 75 ++++++++++++++++++++++++++++++++++-------------
 1 file changed, 55 insertions(+), 20 deletions(-)

(limited to 'm4')

diff --git a/m4/fp_find_cxx_std_lib.m4 b/m4/fp_find_cxx_std_lib.m4
index 68ac0e617d..24f78d0a6f 100644
--- a/m4/fp_find_cxx_std_lib.m4
+++ b/m4/fp_find_cxx_std_lib.m4
@@ -18,10 +18,44 @@ unknown
 #endif
 EOF
         AC_MSG_CHECKING([C++ standard library flavour])
-        if "$CXX" -E actest.cpp -o actest.out; then
-            if grep "libc++" actest.out >/dev/null; then
-                CXX_STD_LIB_LIBS="c++ c++abi"
-                p="`"$CXX" --print-file-name libc++.so`"
+        if ! "$CXX" -E actest.cpp -o actest.out; then
+            rm -f actest.cpp actest.out
+            AC_MSG_ERROR([Failed to compile test program])
+        fi
+
+        dnl Identify standard library type
+        if grep "libc++" actest.out >/dev/null; then
+            CXX_STD_LIB_FLAVOUR="c++"
+            AC_MSG_RESULT([libc++])
+        elif grep "libstdc++" actest.out >/dev/null; then
+            CXX_STD_LIB_FLAVOUR="stdc++"
+            AC_MSG_RESULT([libstdc++])
+        else
+            rm -f actest.cpp actest.out
+            AC_MSG_ERROR([Unknown C++ standard library implementation.])
+        fi
+        rm -f actest.cpp actest.out
+
+        dnl -----------------------------------------
+        dnl Figure out how to link...
+        dnl -----------------------------------------
+        cat >actest.cpp <<-EOF
+#include <iostream>
+int main(int argc, char** argv) {
+    std::cout << "hello world\n";
+    return 0;
+}
+EOF
+        if ! "$CXX" -c actest.cpp; then
+            AC_MSG_ERROR([Failed to compile test object])
+        fi
+
+        try_libs() {
+            dnl Try to link a plain object with CC manually
+            AC_MSG_CHECKING([for linkage against '${3}'])
+            if "$CC" -o actest actest.o ${1} 2>/dev/null; then
+                CXX_STD_LIB_LIBS="${3}"
+                p="`"$CXX" --print-file-name ${2}`"
                 d="`dirname "$p"`"
                 dnl On some platforms (e.g. Windows) the C++ standard library
                 dnl can be found in the system search path. In this case $CXX
@@ -31,24 +65,25 @@ EOF
                 if test "$d" = "."; then d=""; fi
                 CXX_STD_LIB_LIB_DIRS="$d"
                 CXX_STD_LIB_DYN_LIB_DIRS="$d"
-                AC_MSG_RESULT([libc++])
-            elif grep "libstdc++" actest.out >/dev/null; then
-                CXX_STD_LIB_LIBS="stdc++"
-                p="`"$CXX" --print-file-name libstdc++.so`"
-                d="`dirname "$p"`"
-                if test "$d" = "."; then d=""; fi
-                CXX_STD_LIB_LIB_DIRS="$d"
-                CXX_STD_LIB_DYN_LIB_DIRS="$d"
-                AC_MSG_RESULT([libstdc++])
+                AC_MSG_RESULT([success])
+                true
             else
-                rm -f actest.cpp actest.out
-                AC_MSG_ERROR([Unknown C++ standard library implementation.])
+                AC_MSG_RESULT([failed])
+                false
             fi
-            rm -f actest.cpp actest.out
-        else
-            rm -f actest.cpp actest.out
-            AC_MSG_ERROR([Failed to compile test program])
-        fi
+        }
+        case $CXX_STD_LIB_FLAVOUR in
+        c++)
+            try_libs "-lc++ -lc++abi" "libc++.so" "c++ c++abi" || \
+            try_libs "-lc++ -lcxxrt" "libc++.so" "c++ cxxrt" ||
+            AC_MSG_ERROR([Failed to find C++ standard library]) ;;
+        stdc++)
+            try_libs "-lstdc++" "libstdc++.so" "stdc++" || \
+            try_libs "-lstdc++ -lsupc++" "libstdc++.so" "stdc++ supc++" || \
+            AC_MSG_ERROR([Failed to find C++ standard library]) ;;
+        esac
+
+        rm -f actest.cpp actest.o actest
     fi
 
     AC_SUBST([CXX_STD_LIB_LIBS])
-- 
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