Add --force-output-type option

emcc.py

@@ -58,6 +58,8 @@
 JS_CONTAINING_SUFFIXES = ('js', 'html')
 EXECUTABLE_SUFFIXES = JS_CONTAINING_SUFFIXES + ('wasm',)
 
+EXPLICIT_OUTPUT_TYPES = ('js', 'html', 'bc')
+
 DEFERRED_REPONSE_FILES = ('EMTERPRETIFY_BLACKLIST', 'EMTERPRETIFY_WHITELIST')
 
 # Mapping of emcc opt levels to llvm opt levels. We use llvm opt level 3 in emcc opt
@@ -165,6 +167,7 @@ def __init__(self):
     # Specifies the line ending format to use for all generated text files.
     # Defaults to using the native EOL on each platform (\r\n on Windows, \n on Linux&OSX)
     self.output_eol = os.linesep
+    self.force_output_type = None
 
 
 class JSOptimizer(object):
@@ -542,11 +545,6 @@ def uniquename(name):
   target = specified_target if specified_target is not None else 'a.out.js' # specified_target is the user-specified one, target is what we will generate
   target_basename = unsuffixed_basename(target)
 
-  if '.' in target:
-    final_suffix = target.split('.')[-1]
-  else:
-    final_suffix = ''
-
   if TEMP_DIR:
     temp_dir = TEMP_DIR
     if os.path.exists(temp_dir):
@@ -777,24 +775,37 @@ def detect_fixed_language_mode(args):
 
       newargs = [arg for arg in newargs if arg is not '']
 
+      final_suffix = None
       # -c means do not link in gcc, and for us, the parallel is to not go all the way to JS, but stop at bitcode
       has_dash_c = '-c' in newargs
       if has_dash_c:
         assert has_source_inputs or has_header_inputs, 'Must have source code or header inputs to use -c'
-        target = target_basename + '.o'
+        if specified_target == None:
+          target = target_basename + '.o'
         final_suffix = 'o'
       if '-E' in newargs:
         final_suffix = 'eout' # not bitcode, not js; but just result from preprocessing stage of the input file
       if '-M' in newargs or '-MM' in newargs:
         final_suffix = 'mout' # not bitcode, not js; but just dependency rule of the input file
+
+      if final_suffix == None:
+        if options.force_output_type != None:
+          final_suffix = options.force_output_type
+        else:
+          final_suffix = suffix(target)
+          if final_suffix == None:
+            final_suffix = '' # generate bitcode by default
+
       final_ending = ('.' + final_suffix) if len(final_suffix) > 0 else ''
 
+      target_unsuffixed = unsuffixed(target)
+
       # target is now finalized, can finalize other _target s
-      js_target = unsuffixed(target) + '.js'
+      js_target = target if options.force_output_type == 'js' else target_unsuffixed + '.js'
 
-      asm_target = unsuffixed(js_target) + '.asm.js' # might not be used, but if it is, this is the name
-      wasm_text_target = asm_target.replace('.asm.js', '.wast') # ditto, might not be used
-      wasm_binary_target = asm_target.replace('.asm.js', '.wasm') # ditto, might not be used
+      asm_target = target_unsuffixed + '.asm.js' # might not be used, but if it is, this is the name
+      wasm_text_target = target_unsuffixed + '.wast' # ditto, might not be used
+      wasm_binary_target = target_unsuffixed + '.wasm' # ditto, might not be used
 
       if final_suffix == 'html' and not options.separate_asm and ('PRECISE_F32=2' in settings_changes or 'USE_PTHREADS=2' in settings_changes):
         options.separate_asm = True
@@ -827,7 +838,7 @@ def get_last_setting_change(setting):
 
       # If not compiling to JS, then we are compiling to an intermediate bitcode objects or library, so
       # ignore dynamic linking, since multiple dynamic linkings can interfere with each other
-      if filename_type_suffix(target) not in JS_CONTAINING_SUFFIXES or options.ignore_dynamic_linking:
+      if final_suffix not in JS_CONTAINING_SUFFIXES or options.ignore_dynamic_linking:
         def check(input_file):
           if filename_type_ending(input_file) in DYNAMICLIB_ENDINGS:
             if not options.ignore_dynamic_linking: logging.warning('ignoring dynamic library %s because not compiling to JS or HTML, remember to link it when compiling to JS or HTML at the end', os.path.basename(input_file))
@@ -2102,6 +2113,14 @@ def parse_args(newargs):
         exit(1)
       newargs[i] = ''
       newargs[i+1] = ''
+    elif newargs[i] == '--force-output-type':
+      if newargs[i+1] in EXPLICIT_OUTPUT_TYPES:
+        options.force_output_type = newargs[i+1]
+      else:
+        logging.error('Invalid value "' + newargs[i+1] + '" to --force-output-type')
+        exit(1)
+      newargs[i] = ''
+      newargs[i+1] = ''
 
   if should_exit:
     sys.exit(0)

tests/test_other.py

@@ -7890,3 +7890,44 @@ def test_include_system_header_in_c(self):
         print inc
         open('a.c', 'w').write(inc)
         subprocess.check_call([PYTHON, EMCC, 'a.c'])
+
+  def test_force_output_type(self):
+    test_file = os.path.join(self.get_dir(), 'test.cpp')
+    fout = open(test_file, 'w')
+    fout.write('int main() { return 0; }')
+    fout.close()
+
+    def assert_is_bc(filepath):
+      fin = open(filepath, 'rb')
+      try:
+        magic = fin.read(2)
+      finally:
+        fin.close()
+      assert magic[0] == 'B' and magic[1] == 'C'
+
+    def assert_is_js(filepath):
+      fin = open(filepath, 'r')
+      try:
+        content = fin.read()
+      finally:
+        fin.close()
+      self.assertContained('function', content)
+
+    def assert_is_html(filepath):
+      fin = open(filepath, 'r')
+      try:
+        content = fin.read()
+      finally:
+        fin.close()
+      assert content.lstrip().lower().startswith('<!doctype')
+
+    output_types = [ ('bc',   assert_is_bc),
+                     ('js',   assert_is_js),
+                     ('html', assert_is_html),
+    ]
+
+    for output_type, verifier in output_types:
+      for output_suffix in ['', '.o', '.js', '.html', '.somesuffix']:
+        output_path = os.path.join(self.get_dir(), 'output' + output_suffix)
+        subprocess.check_call([PYTHON, EMCC, '--force-output-type', output_type, test_file, '-o', output_path])
+        verifier(output_path)