Compile with -std=c++03 consistently on all platforms. By default, Clang 3.2 inconsistently uses C++11 for Windows and C++03 for Linux if user did not specify -std= on the command line. Fixes other.test_embind and *.test_llvmswitch. Add unit tests that confirm that .cpp files are compiled with C++03 std by default.

emcc

@@ -596,6 +596,10 @@ try:
   keep_debug = False
   bind = False
   jcache = False
+  if use_cxx:
+    default_cxx_std = '-std=c++03' # Enforce a consistent C++ standard when compiling .cpp files, if user does not specify one on the cmdline.
+  else:
+    default_cxx_std = '' # Compiling C code with .c files, don't enforce a default C++ std.
 
   def check_bad_eq(arg):
     assert '=' not in arg, 'Invalid parameter (do not use "=" with "--" options)'
@@ -659,7 +663,11 @@ try:
       keep_debug = True
     elif newargs[i] == '--bind':
       bind = True
-      newargs[i] = '-std=c++11' # Force C++11 for embind code
+      newargs[i] = ''
+      if default_cxx_std:
+        default_cxx_std = '-std=c++11' # Force C++11 for embind code, but only if user has not explicitly overridden a standard.
+    elif newargs[i].startswith('-std='):
+      default_cxx_std = '' # User specified a standard to use, clear Emscripten from specifying it.
     elif newargs[i].startswith('--embed-file'):
       check_bad_eq(newargs[i])
       embed_files.append(newargs[i+1])
@@ -717,6 +725,10 @@ try:
         absolute_warning_shown = True
   newargs = [ arg for arg in newargs if arg is not '' ]
 
+  # If user did not specify a default -std for C++ code, specify the emscripten default.
+  if default_cxx_std:
+    newargs = newargs + [default_cxx_std]
+
   if llvm_opts is None: llvm_opts = LLVM_OPT_LEVEL[opt_level]
   if llvm_lto is None: llvm_lto = llvm_opts > 0
   if closure is None: closure = 1 if opt_level >= 2 else 0

tests/hello_cxx03.cpp

@@ -0,0 +1,10 @@
+#include <stdio.h>
+
+#if __cplusplus != 199711L
+#error By default, if no -std is specified, emscripten should be compiling with -std=c++03!
+#endif
+
+int main( int argc, const char *argv[] ) {
+  printf("Hello world!\\n");
+  return 0;
+}

tests/runner.py

@@ -238,7 +238,7 @@ process(sys.argv[1])
         os.remove(f + '.o')
       except:
         pass
-      args = [Building.COMPILER, '-emit-llvm'] + COMPILER_OPTS + Building.COMPILER_TEST_OPTS + \
+      args = [Building.COMPILER, '-emit-llvm', '-std=c++03'] + COMPILER_OPTS + Building.COMPILER_TEST_OPTS + \
              ['-I', dirname, '-I', os.path.join(dirname, 'include')] + \
              map(lambda include: '-I' + include, includes) + \
              ['-c', f, '-o', f + '.o']
@@ -3517,7 +3517,7 @@ def process(filename):
     # i.e. as if "-std=c++03" had been passed on the command line. On Linux with Clang 3.2 this is the case, but on Windows
     # with Clang 3.2 -std=c++11 has been chosen as default, because of
     # < jrose> clb: it's deliberate, with the idea that for people who don't care about the standard, they should be using the "best" thing we can offer on that platform
-    def test_cxx03(self):
+    def test_cxx03_do_run(self):
         src = '''
           #include <stdio.h>
           
@@ -8406,6 +8406,12 @@ f.close()
         assert process.returncode is not 0, 'Trying to compile a nonexisting file should return with a nonzero error code!'
         assert os.path.exists('this_output_file_should_never_exist.js') == False, 'Emcc should not produce an output file when build fails!'
 
+    def test_cxx03(self):
+      for compiler in [EMCC, EMXX]:
+        process = Popen([PYTHON, compiler, path_from_root('tests', 'hello_cxx03.cpp')], stdout=PIPE, stderr=PIPE)
+        process.communicate()
+        assert process.returncode is 0, 'By default, emscripten should build using -std=c++03!'
+
     def test_Os(self):
       for opt in ['s', '0']:
         output = Popen([PYTHON, EMCC, path_from_root('tests', 'hello_world.c'), '-O' + opt], stdout=PIPE, stderr=PIPE).communicate()