[emcc.py] Move -c/-s/-E parsing the main arg parsing loop. NFC (#23434)

emcc.py

@@ -113,9 +113,6 @@ def __init__(self, args):
     self.mode = Mode.COMPILE_AND_LINK
     # Using tuple here to prevent accidental mutation
     self.orig_args = tuple(args)
-    self.has_dash_c = False
-    self.has_dash_E = False
-    self.has_dash_S = False
     # List of link options paired with their position on the command line [(i, option), ...].
     self.link_flags = []
     self.lib_dirs = []
@@ -179,6 +176,11 @@ def __init__(self):
     self.shared = False
     self.relocatable = False
     self.reproduce = None
+    self.syntax_only = False
+    self.dash_c = False
+    self.dash_E = False
+    self.dash_S = False
+    self.dash_M = False
 
 
 def create_reproduce_file(name, args):
@@ -817,17 +819,13 @@ def phase_setup(options, state, newargs):
   # so it won't think about generating native x86 SSE code.
   newargs = [x for x in newargs if x not in SIMD_INTEL_FEATURE_TOWER and x not in SIMD_NEON_FLAGS]
 
-  state.has_dash_c = '-c' in newargs or '--precompile' in newargs
-  state.has_dash_S = '-S' in newargs
-  state.has_dash_E = '-E' in newargs
-
   if options.post_link:
     state.mode = Mode.POST_LINK_ONLY
-  elif state.has_dash_E or '-M' in newargs or '-MM' in newargs or '-fsyntax-only' in newargs:
+  elif options.dash_E or options.dash_M:
     state.mode = Mode.PREPROCESS_ONLY
   elif has_header_inputs:
     state.mode = Mode.PCH
-  elif state.has_dash_c or state.has_dash_S:
+  elif options.dash_c or options.dash_S or options.syntax_only:
     state.mode = Mode.COMPILE_ONLY
 
   if state.mode in (Mode.COMPILE_ONLY, Mode.PREPROCESS_ONLY):
@@ -984,7 +982,7 @@ def get_clang_command_preprocessed():
   def get_clang_command_asm():
     return compiler + get_target_flags() + compile_args
 
-  # preprocessor-only (-E) support
+  # preprocessor-only (-E/-M) support
   if state.mode == Mode.PREPROCESS_ONLY:
     inputs = [i[1] for i in input_files]
     cmd = get_clang_command() + inputs
@@ -993,7 +991,7 @@ def get_clang_command_asm():
     # Do not compile, but just output the result from preprocessing stage or
     # output the dependency rule. Warning: clang and gcc behave differently
     # with -MF! (clang seems to not recognize it)
-    logger.debug(('just preprocessor ' if state.has_dash_E else 'just dependencies: ') + ' '.join(cmd))
+    logger.debug(('just preprocessor: ' if options.dash_E else 'just dependencies: ') + ' '.join(cmd))
     shared.exec_process(cmd)
     assert False, 'exec_process does not return'
 
@@ -1026,7 +1024,7 @@ def get_clang_command_asm():
   # In COMPILE_AND_LINK we need to compile source files too, but we also need to
   # filter out the link flags
   assert state.mode == Mode.COMPILE_AND_LINK
-  assert not state.has_dash_c
+  assert not options.dash_c
   compile_args = filter_out_link_flags(compile_args)
   linker_inputs = []
   seen_names = {}
@@ -1069,7 +1067,7 @@ def compile_source_file(i, input_file):
   # First, generate LLVM bitcode. For each input file, we get base.o with bitcode
   for i, input_file in input_files:
     file_suffix = get_file_suffix(input_file)
-    if file_suffix in SOURCE_ENDINGS + ASSEMBLY_ENDINGS or (state.has_dash_c and file_suffix == '.bc'):
+    if file_suffix in SOURCE_ENDINGS + ASSEMBLY_ENDINGS or (options.dash_c and file_suffix == '.bc'):
       compile_source_file(i, input_file)
     elif file_suffix in DYNAMICLIB_ENDINGS:
       logger.debug(f'using shared library: {input_file}')
@@ -1486,6 +1484,16 @@ def consume_arg_file():
         exit_with_error(f'unsupported target: {options.target} (emcc only supports wasm64-unknown-emscripten and wasm32-unknown-emscripten)')
     elif check_arg('--use-port'):
       ports.handle_use_port_arg(settings, consume_arg())
+    elif arg in ('-c', '--precompile'):
+      options.dash_c = True
+    elif arg == '-S':
+      options.dash_S = True
+    elif arg == '-E':
+      options.dash_E = True
+    elif arg in ('-M', '-MM'):
+      options.dash_M = True
+    elif arg == '-fsyntax-only':
+      options.syntax_only = True
 
   if should_exit:
     sys.exit(0)

test/test_other.py

@@ -3861,6 +3861,9 @@ def test_syntax_only_valid(self):
     result = self.run_process([EMCC, test_file('hello_world.c'), '-fsyntax-only'], stdout=PIPE, stderr=STDOUT)
     self.assertEqual(result.stdout, '')
     self.assertNotExists('a.out.js')
+    # Even with `-c` and/or `-o`, `-fsyntax-only` should not produce any output
+    self.run_process([EMCC, test_file('hello_world.c'), '-fsyntax-only', '-c', '-o', 'out.o'])
+    self.assertNotExists('out.o')
 
   def test_syntax_only_invalid(self):
     create_file('src.c', 'int main() {')