fixed emscripten detection (#897)

.github/workflows/emscripten.yml

@@ -40,7 +40,6 @@ jobs:
           cmake -S . -B build_${{matrix.build_type}} \
             -DBUILD_SHARED_LIBS=${{matrix.lib == 'shared'}} \
             -DCMAKE_AR=$(which emar) \
-            -DCMAKE_C_COMPILER=$(which emcc) \
             -DCMAKE_CXX_COMPILER=$(which em++) \
             -DCMAKE_CXX_STANDARD=${{matrix.std}} \
             -DCMAKE_CXX_STANDARD_REQUIRED=ON \

CMakeLists.txt

@@ -503,15 +503,25 @@ if (WITH_SYMBOLIZE)
     if (HAVE_SYMBOLIZE)
       set (HAVE_STACKTRACE 1)
     endif (HAVE_SYMBOLIZE)
-  elseif (UNIX OR (APPLE AND HAVE_DLADDR))
+  elseif (UNIX)
+    cmake_push_check_state (RESET)
+    check_cxx_source_compiles ([=[
+    int main()
+    {
+      #ifndef __ELF__
+      #error __ELF__ not defined
+      #endif
+    }
+    ]=] HAVE_SYMBOLIZE)
+    cmake_pop_check_state ()
+  elseif (APPLE AND HAVE_DLADDR)
     set (HAVE_SYMBOLIZE 1)
   endif (WIN32 OR CYGWIN)
 endif (WITH_SYMBOLIZE)
 
 # CMake manages symbolize availability. The definition is necessary only when
-# building the library. Switch to add_compile_definitions once we drop support
-# for CMake below version 3.12.
-add_definitions (-DGLOG_NO_SYMBOLIZE_DETECTION)
+# building the library.
+add_compile_definitions (GLOG_NO_SYMBOLIZE_DETECTION)
 
 check_cxx_source_compiles ("
 #include <cstdlib>

src/symbolize.cc

@@ -834,7 +834,7 @@ static ATTRIBUTE_NOINLINE bool SymbolizeAndDemangle(void *pc, char *out,
 
 _END_GOOGLE_NAMESPACE_
 
-#elif (defined(GLOG_OS_MACOSX) || defined(GLOG_OS_EMSCRIPTEN)) && defined(HAVE_DLADDR)
+#elif defined(GLOG_OS_MACOSX) && defined(HAVE_DLADDR)
 
 #include <dlfcn.h>
 #include <cstring>