xo-arena: build: can't assume elfutils on osx

src/arena/CMakeLists.txt

@@ -25,7 +25,11 @@ xo_install_include_tree3(include/xo/arena)
 
 xo_dependency(${SELF_LIB} xo_reflectutil)
 xo_dependency(${SELF_LIB} indentlog)
+
+if (NOT APPLE)
 xo_external_pkgconfig_dependency(${SELF_LIB} LIBUNWIND libunwind-generic)
 xo_external_pkgconfig_dependency(${SELF_LIB} LIBDW libdw)
+else()
+endif()
 
 # end src/CMakeLists.txt

src/arena/DArena.cpp

@@ -12,6 +12,7 @@
 #include <xo/indentlog/scope.hpp>
 #include <xo/indentlog/print/tag.hpp>
 #include <cassert>
+#include <exception>
 #include <sys/mman.h> // for ::munmap()
 #include <unistd.h> // for ::getpagesize()
 #include <string.h> // for ::memset()
@@ -587,7 +588,7 @@ namespace xo {
 
                     fprintf(stderr, "DArena::expand: mprotect failed (system oom?)");
                     print_backtrace_dwarf(false /*!demangle_flag*/);
-                    
+
                     return false;
                 }
 

src/arena/backtrace.cpp

@@ -4,13 +4,16 @@
  **/
 
 #include "backtrace.hpp"
+#include <iostream>
 #include <array>
 #include <cstdio>
 #include <cstdlib>
 #include <libunwind.h>
 #include <cxxabi.h>
 #include <unistd.h>
-#include <elfutils/libdwfl.h>
+#ifndef __APPLE__
+#  include <elfutils/libdwfl.h>
+#endif
 
 namespace xo {
     void
@@ -67,6 +70,7 @@ namespace xo {
         }
     }
     namespace {
+#ifndef __APPLE__
         // libdwfl requires callbacks for find_elf and find_debuginfo.
         // The offline defaults work for the current process.
         //
@@ -76,10 +80,18 @@ namespace xo {
             .section_address = nullptr,
             .debuginfo_path = nullptr,
         };
+#endif
     }
 
     void
-    print_backtrace_dwarf(bool demangle_flag) {
+    print_backtrace_dwarf(bool demangle_flag)
+    {
+
+#ifdef __APPLE__
+        (void)demangle_flag;
+
+        std::cerr << "backtrace with dwarf symbols not supported on osx" << std::endl;
+#else
         unw_cursor_t cursor;
         unw_context_t cx;
 
@@ -152,6 +164,8 @@ namespace xo {
 
         if (dwfl)
             dwfl_end(dwfl);
+#endif
+
     }
 } /*namespace xo*/