Move all command line flag processing to emcc.py. NFC (#23497)

This change paves to the way for link.py refactor I'm working on, but it
also seems like a good idea to keep argument processing in one place.

emcc.py

@@ -183,6 +183,13 @@ def __init__(self):
     self.dash_S = False
     self.dash_M = False
     self.input_language = None
+    self.nostdlib = False
+    self.nostdlibxx = False
+    self.nodefaultlibs = False
+    self.nolibc = False
+    self.nostartfiles = False
+    self.sanitize_minimal_runtime = False
+    self.sanitize = set()
 
 
 def create_reproduce_file(name, args):
@@ -1421,6 +1428,22 @@ def consume_arg_file():
       # SSEx is implemented on top of SIMD128 instruction set, but do not pass SSE flags to LLVM
       # so it won't think about generating native x86 SSE code.
       newargs[i] = ''
+    elif arg == '-nostdlib':
+      options.nostdlib = True
+    elif arg == '-nostdlibxx':
+      options.nostdlibxx = True
+    elif arg == '-nodefaultlibs':
+      options.nodefaultlibs = True
+    elif arg == '-nolibc':
+      options.nolibc = True
+    elif arg == '-nostartfiles':
+      options.nostartfiles = True
+    elif arg == '-fsanitize-minimal-runtime':
+      options.sanitize_minimal_runtime = True
+    elif arg.startswith('-fsanitize='):
+      options.sanitize.update(arg.split('=', 1)[1].split(','))
+    elif arg.startswith('-fno-sanitize='):
+      options.sanitize.difference_update(arg.split('=', 1)[1].split(','))
     elif arg and (arg == '-' or not arg.startswith('-')):
       options.input_files.append(arg)
 

tools/link.py

@@ -655,7 +655,7 @@ def phase_linker_setup(options, state):  # noqa: C901, PLR0912, PLR0915
   if not shared.SKIP_SUBPROCS:
     shared.check_llvm_version()
 
-  autoconf = os.environ.get('EMMAKEN_JUST_CONFIGURE') or 'conftest.c' in state.orig_args or 'conftest.cpp' in state.orig_args
+  autoconf = os.environ.get('EMMAKEN_JUST_CONFIGURE') or 'conftest.c' in options.input_files or 'conftest.cpp' in options.input_files
   if autoconf:
     # configure tests want a more shell-like style, where we emit return codes on exit()
     settings.EXIT_RUNTIME = 1
@@ -899,7 +899,7 @@ def phase_linker_setup(options, state):  # noqa: C901, PLR0912, PLR0915
     # PURE_WASI, or when we are linking without standard libraries because
     # STACK_OVERFLOW_CHECK depends on emscripten_stack_get_end which is defined
     # in libcompiler-rt.
-    if not settings.PURE_WASI and '-nostdlib' not in state.orig_args and '-nodefaultlibs' not in state.orig_args:
+    if not settings.PURE_WASI and not options.nostdlib and not options.nodefaultlibs:
       default_setting('STACK_OVERFLOW_CHECK', max(settings.ASSERTIONS, settings.STACK_OVERFLOW_CHECK))
 
   # For users that opt out of WARN_ON_UNDEFINED_SYMBOLS we assume they also
@@ -1536,15 +1536,7 @@ def phase_linker_setup(options, state):  # noqa: C901, PLR0912, PLR0915
   if settings.SIDE_MODULE and shared.suffix(target) == '.js':
     diagnostics.warning('emcc', 'output suffix .js requested, but wasm side modules are just wasm files; emitting only a .wasm, no .js')
 
-  sanitize = set()
-
-  for arg in state.orig_args:
-    if arg.startswith('-fsanitize='):
-      sanitize.update(arg.split('=', 1)[1].split(','))
-    elif arg.startswith('-fno-sanitize='):
-      sanitize.difference_update(arg.split('=', 1)[1].split(','))
-
-  if sanitize:
+  if options.sanitize:
     settings.USE_OFFSET_CONVERTER = 1
     # These symbols are needed by `withBuiltinMalloc` which used to implement
     # the `__noleakcheck` attribute.  However this dependency is not yet represented in the JS
@@ -1560,7 +1552,7 @@ def phase_linker_setup(options, state):  # noqa: C901, PLR0912, PLR0915
       'emscripten_builtin_free',
     ]
 
-  if ('leak' in sanitize or 'address' in sanitize) and not settings.ALLOW_MEMORY_GROWTH:
+  if ('leak' in options.sanitize or 'address' in options.sanitize) and not settings.ALLOW_MEMORY_GROWTH:
     # Increase the minimum memory requirements to account for extra memory
     # that the sanitizers might need (in addition to the shadow memory
     # requirements handled below).
@@ -1576,17 +1568,17 @@ def phase_linker_setup(options, state):  # noqa: C901, PLR0912, PLR0915
       exit_with_error('wasm2js is not compatible with USE_OFFSET_CONVERTER (see #14630)')
     settings.DEFAULT_LIBRARY_FUNCS_TO_INCLUDE.append('$UTF8ArrayToString')
 
-  if sanitize & UBSAN_SANITIZERS:
-    if '-fsanitize-minimal-runtime' in state.orig_args:
+  if options.sanitize & UBSAN_SANITIZERS:
+    if options.sanitize_minimal_runtime:
       settings.UBSAN_RUNTIME = 1
     else:
       settings.UBSAN_RUNTIME = 2
 
-  if 'leak' in sanitize:
+  if 'leak' in options.sanitize:
     settings.USE_LSAN = 1
     default_setting('EXIT_RUNTIME', 1)
 
-  if 'address' in sanitize:
+  if 'address' in options.sanitize:
     settings.USE_ASAN = 1
     default_setting('EXIT_RUNTIME', 1)
     if not settings.UBSAN_RUNTIME:
@@ -1661,7 +1653,7 @@ def phase_linker_setup(options, state):  # noqa: C901, PLR0912, PLR0915
     # ASan and SAFE_HEAP check address 0 themselves
     settings.CHECK_NULL_WRITES = 0
 
-  if sanitize and settings.GENERATE_SOURCE_MAP:
+  if options.sanitize and settings.GENERATE_SOURCE_MAP:
     settings.LOAD_SOURCE_MAP = 1
 
   if 'GLOBAL_BASE' not in user_settings and not settings.SHRINK_LEVEL and not settings.OPT_LEVEL and not settings.USE_ASAN:
@@ -1792,7 +1784,7 @@ def get_full_import_name(name):
   settings.EMSCRIPTEN_VERSION = utils.EMSCRIPTEN_VERSION
   settings.SOURCE_MAP_BASE = options.source_map_base or ''
 
-  settings.LINK_AS_CXX = (shared.run_via_emxx or settings.DEFAULT_TO_CXX) and '-nostdlib++' not in state.orig_args
+  settings.LINK_AS_CXX = (shared.run_via_emxx or settings.DEFAULT_TO_CXX) and not options.nostdlibxx
 
   # WASMFS itself is written in C++, and needs C++ standard libraries
   if settings.WASMFS:
@@ -1867,13 +1859,13 @@ def get_full_import_name(name):
 
 
 @ToolchainProfiler.profile_block('calculate system libraries')
-def phase_calculate_system_libraries(state, linker_arguments):
+def phase_calculate_system_libraries(options, linker_arguments):
   extra_files_to_link = []
   # Link in ports and system libraries, if necessary
   if not settings.SIDE_MODULE:
     # Ports are always linked into the main module, never the side module.
     extra_files_to_link += ports.get_libs(settings)
-  extra_files_to_link += system_libs.calculate(state.orig_args)
+  extra_files_to_link += system_libs.calculate(options)
   linker_arguments.extend(extra_files_to_link)
 
 
@@ -3128,7 +3120,7 @@ def run(linker_inputs, options, state):
     logger.debug('stopping after linking to object file')
     return 0
 
-  phase_calculate_system_libraries(state, linker_arguments)
+  phase_calculate_system_libraries(options, linker_arguments)
 
   js_syms = {}
   if (not settings.SIDE_MODULE or settings.ASYNCIFY) and not shared.SKIP_SUBPROCS:

tools/system_libs.py

@@ -2234,10 +2234,10 @@ class libstubs(DebugLibrary):
   src_files = ['emscripten_syscall_stubs.c', 'emscripten_libc_stubs.c']
 
 
-def get_libs_to_link(args):
+def get_libs_to_link(options):
   libs_to_link = []
 
-  if '-nostdlib' in args:
+  if options.nostdlib:
     return libs_to_link
 
   already_included = set()
@@ -2277,7 +2277,7 @@ def add_library(libname, whole_archive=False):
     need_whole_archive = lib.name in force_include and lib.get_ext() == '.a'
     libs_to_link.append((lib.get_link_flag(), whole_archive or need_whole_archive))
 
-  if '-nostartfiles' not in args:
+  if not options.nostartfiles:
     if settings.SHARED_MEMORY:
       add_library('crtbegin')
 
@@ -2302,7 +2302,7 @@ def add_forced_libs():
         shared.exit_with_error('invalid forced library: %s', forced)
       add_library(forced)
 
-  if '-nodefaultlibs' in args:
+  if options.nodefaultlibs:
     add_forced_libs()
     return libs_to_link
 
@@ -2355,7 +2355,7 @@ def add_sanitizer_libs():
     add_library('libstandalonewasm')
   if settings.ALLOW_UNIMPLEMENTED_SYSCALLS:
     add_library('libstubs')
-  if '-nolibc' not in args:
+  if not options.nolibc:
     if not settings.EXIT_RUNTIME:
       add_library('libnoexit')
     add_library('libc')
@@ -2407,9 +2407,9 @@ def add_sanitizer_libs():
   return libs_to_link
 
 
-def calculate(args):
+def calculate(options):
 
-  libs_to_link = get_libs_to_link(args)
+  libs_to_link = get_libs_to_link(options)
 
   # When LINKABLE is set the entire link command line is wrapped in --whole-archive by
   # building.link_ldd.  And since --whole-archive/--no-whole-archive processing does not nest we