[mobile_static] Use clang++ for the linker (#3308)

In order for our exception handling to work on linux, we need the
unwind-dw2-fde-dip implementation in libgcc to work with our
.o file. This requires that `--eh-frame-hdr` be passed by the linker.

By using clang++ as the linker, we will get this and other flags
necessary for correct interop with c++ libraries.

diff --git a/mono/mini/aot-compiler.c b/mono/mini/aot-compiler.c
index c60b9092ce3e1b9118d491a8012d2fc531dded86..7791ec26d0b55fbff726f895120fea3eb16e118b 100644 (file)
--- a/mono/mini/aot-compiler.c
+++ b/mono/mini/aot-compiler.c
@@ -8264,7 +8264,7 @@ emit_llvm_file (MonoAotCompile *acfg)
        if (acfg->aot_opts.llvm_only) {
                /* Use the stock clang from xcode */
                // FIXME: arch
-               command = g_strdup_printf ("clang -march=x86-64 -fpic -msse -msse2 -msse3 -msse4 -O2 -fno-optimize-sibling-calls -Wno-override-module -c -o \"%s\" \"%s.opt.bc\"", acfg->llvm_ofile, acfg->tmpbasename);
+               command = g_strdup_printf ("clang++ -fexceptions -march=x86-64 -fpic -msse -msse2 -msse3 -msse4 -O2 -fno-optimize-sibling-calls -Wno-override-module -c -o \"%s\" \"%s.opt.bc\"", acfg->llvm_ofile, acfg->tmpbasename);
 
                aot_printf (acfg, "Executing clang: %s\n", command);
                if (execute_system (command) != 0)
@@ -9965,9 +9965,17 @@ compile_asm (MonoAotCompile *acfg)
                wrap_path (g_strdup_printf ("%s.o", acfg->tmpfname)), ld_flags);
 #else
        // Default (linux)
-       command = g_strdup_printf ("\"%sld\" %s -shared -o %s %s %s %s", tool_prefix, LD_OPTIONS,
+       char *args = g_strdup_printf ("%s %s -shared -o %s %s %s %s", tool_prefix, LD_OPTIONS,
                wrap_path (tmp_outfile_name), wrap_path (llvm_ofile),
                wrap_path (g_strdup_printf ("%s.o", acfg->tmpfname)), ld_flags);
+
+       if (acfg->llvm) {
+               command = g_strdup_printf ("clang++ %s", args);
+       } else {
+               command = g_strdup_printf ("\"%sld\" %s", tool_prefix, args);
+       }
+       g_free (args);
+
 #endif
        aot_printf (acfg, "Executing the native linker: %s\n", command);
        if (execute_system (command) != 0) {