Support gcc 4.8.5, resolves #220

CMakeLists.txt

@@ -34,12 +34,20 @@ endif()
 if(PROJECT_IS_TOP_LEVEL)
   if(CMAKE_GENERATOR STREQUAL "Ninja")
     if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
-      SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fdiagnostics-color=always")
+      include(CheckCXXCompilerFlag)
+      check_cxx_compiler_flag(-fdiagnostics-color=always HAS_CXX_FDIAGNOSTICS_COLOR)
+      if(HAS_CXX_FDIAGNOSTICS_COLOR)
+        SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fdiagnostics-color=always")
+      endif()
     elseif("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "AppleClang")
       SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fcolor-diagnostics")
     endif()
     if("${CMAKE_C_COMPILER_ID}" STREQUAL "GNU")
-      SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fdiagnostics-color=always")
+      include(CheckCCompilerFlag)
+      check_c_compiler_flag(-fdiagnostics-color=always HAS_C_FDIAGNOSTICS_COLOR)
+      if(HAS_C_FDIAGNOSTICS_COLOR)
+        SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fdiagnostics-color=always")
+      endif()
     elseif("${CMAKE_C_COMPILER_ID}" STREQUAL "Clang" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "AppleClang")
       SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fcolor-diagnostics")
     endif()
@@ -176,6 +184,11 @@ target_compile_options(
   ${warning_options}
 )
 
+if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 6.0)
+  # https://godbolt.org/z/qYh89E6rq
+  target_compile_options(${target_name} PRIVATE -Wno-missing-field-initializers)
+endif()
+
 set(CPPTRACE_VERSION_MAJOR ${CMAKE_PROJECT_VERSION_MAJOR})
 set(CPPTRACE_VERSION_MINOR ${CMAKE_PROJECT_VERSION_MINOR})
 set(CPPTRACE_VERSION_PATCH ${CMAKE_PROJECT_VERSION_PATCH})

src/binary/elf.cpp

@@ -424,7 +424,7 @@ namespace detail {
             static std::unordered_map<std::string, Result<elf, internal_error>> cache;
             auto it = cache.find(object_path);
             if(it == cache.end()) {
-                auto res = cache.insert({ object_path, elf::open_elf(object_path) });
+                auto res = cache.emplace(object_path, elf::open_elf(object_path));
                 VERIFY(res.second);
                 it = res.first;
             }

src/from_current.cpp

@@ -272,7 +272,8 @@ namespace cpptrace {
             memcpy(new_vtable_page, type_info_vtable_pointer, vtable_size * sizeof(void*));
             // ninja in the custom __do_catch interceptor
             auto new_vtable = static_cast<void**>(new_vtable_page);
-            new_vtable[6] = reinterpret_cast<void*>(do_catch_function);
+            // double cast is done here because older (and some newer gcc versions) warned about it under -Wpedantic
+            new_vtable[6] = reinterpret_cast<void*>(reinterpret_cast<std::uintptr_t>(do_catch_function));
             // make the page read-only
             mprotect_page(new_vtable_page, page_size, memory_readonly);
 

src/symbols/dwarf/dwarf_resolver.cpp

@@ -324,7 +324,7 @@ namespace libdwarf {
                     char** dw_srcfiles;
                     Dwarf_Signed dw_filecount;
                     VERIFY(wrap(dwarf_srcfiles, cu_die.get(), &dw_srcfiles, &dw_filecount) == DW_DLV_OK);
-                    it = srcfiles_cache.insert(it, {off, srcfiles{cu_die.dbg, dw_srcfiles, dw_filecount}});
+                    it = srcfiles_cache.emplace_hint(it, off, srcfiles{cu_die.dbg, dw_srcfiles, dw_filecount});
                 }
                 if(file_i < it->second.count()) {
                     // dwarf is using 1-indexing

src/symbols/dwarf/dwarf_utils.hpp

@@ -67,7 +67,14 @@ namespace libdwarf {
     // sorted range entries for dies
     template<
         typename T,
-        typename std::enable_if<std::is_trivially_copyable<T>::value && sizeof(T) <= 16, int>::type = 0
+        typename std::enable_if<
+            // old gcc doesn't support this trait https://godbolt.org/z/fKWT9jTK7
+            #if !(defined(__GNUC__) && (__GNUC__ < 5))
+             std::is_trivially_copyable<T>::value &&
+            #endif
+            sizeof(T) <= 16,
+            int
+        >::type = 0
     >
     class die_cache {
     public:

src/utils/common.hpp

@@ -24,6 +24,13 @@
  #define NODISCARD
 #endif
 
+// workaround a bizarre gcc bug https://godbolt.org/z/s78vnf7jv
+// https://github.com/jeremy-rifkin/cpptrace/issues/220
+#if defined(__GNUC__) && (__GNUC__ < 7)
+ #undef NODISCARD
+ #define NODISCARD
+#endif
+
 #if IS_MSVC
  #define MSVC_CDECL __cdecl
 #else