Mark WASM_BIGINT as deprecated

ChangeLog.md

@@ -33,6 +33,9 @@ See docs/process.md for more on how version tagging works.
   disabling of `WASM_BIGINT` itself should only be needed under `-sWASM=0`
   (where it is automatically disabled). (#27568)
 - The `SOCKET_WEBRTC` setting was removed (#27367)
+- `WASM_BIGINT` was deprecated. BigInt integration is standard and enabled by
+  default across all supported engines; it should now only ever be disabled
+  implicitly when targeting JavaScript via `-sWASM=0`. (#27558)
 
 6.0.7 - 08/17/26
 ----------------

site/source/docs/tools_reference/settings_reference.rst

@@ -2139,6 +2139,8 @@ WebAssembly integration with JavaScript BigInt. When enabled we don't need to
 legalize i64s into pairs of i32s, as the wasm VM will use a BigInt where an
 i64 is used.
 
+.. note:: This setting is deprecated
+
 Default value: true
 
 .. _emit_producers_section:
@@ -3521,6 +3523,7 @@ these settings please open a bug (or reply to one of the existing bugs).
 
  - ``RUNTIME_LINKED_LIBS``: you can simply list the libraries directly on the commandline now
  - ``CLOSURE_WARNINGS``: use -Wclosure/-Wno-closure instead
+ - ``WASM_BIGINT``: no longer needed. Should only ever be implicitly disabled by -sWASM=0
  - ``ASYNCIFY_EXPORTS``: please use JSPI_EXPORTS instead
  - ``LINKABLE``: under consideration for removal (https://github.com/emscripten-core/emscripten/issues/25262)
  - ``EXPORT_EXCEPTION_HANDLING_HELPERS``: getExceptionMessage is exported anyway when ASSERTIONS or EXCEPTION_STACK_TRACES is set, which are set by default at -O0. At -O1 or above, you can export it separately by -sEXPORTED_RUNTIME_METHODS=getExceptionMessage,decrementExceptionRefcount.

src/settings.js

@@ -1490,6 +1490,7 @@ var DYNCALLS = false;
 // legalize i64s into pairs of i32s, as the wasm VM will use a BigInt where an
 // i64 is used.
 // [link]
+// [deprecated]
 var WASM_BIGINT = true;
 
 // WebAssembly defines a "producers section" which compilers and tools can

test/decorators.py

@@ -416,24 +416,6 @@ def metafunc(self, with_minimal_runtime, *args, **kwargs):
   return metafunc
 
 
-def also_without_bigint(func):
-  assert callable(func)
-
-  @wraps(func)
-  def metafunc(self, no_bigint, *args, **kwargs):
-    if DEBUG:
-      print('parameterize:no_bigint=%s' % no_bigint)
-    if no_bigint:
-      if self.get_setting('WASM_BIGINT') is not None:
-        self.skipTest('redundant in bigint test config')
-      self.set_setting('WASM_BIGINT', 0)
-    return func(self, *args, **kwargs)
-
-  parameterize(metafunc, {'': (False,),
-                          'no_bigint': (True,)})
-  return metafunc
-
-
 def also_with_wasm64(func):
   assert callable(func)
 

test/test_browser.py

@@ -3203,8 +3203,6 @@ def test_cocos2d_hello(self):
     'asyncify': (['-sASYNCIFY'],),
     'asyncify_minimal_runtime': (['-sMINIMAL_RUNTIME', '-sASYNCIFY'],),
     'jspi': (['-sJSPI'],),
-    'jspi_wasm_bigint': (['-sJSPI', '-sWASM_BIGINT'],),
-    'jspi_wasm_bigint_minimal_runtime': (['-sMINIMAL_RUNTIME', '-sJSPI', '-sWASM_BIGINT'],),
   })
   def test_async(self, opt, args):
     if is_jspi(args) and not is_chrome():
@@ -3873,8 +3871,8 @@ def test_pthread_printf(self, args):
   def test_pthread_iostream(self):
     self.btest_exit('pthread/test_pthread_iostream.cpp', cflags=['-O3', '-pthread', '-sPTHREAD_POOL_SIZE'])
 
-  def test_pthread_unistd_io_bigint(self):
-    self.btest_exit('unistd/io.c', cflags=['-pthread', '-sPROXY_TO_PTHREAD', '-sWASM_BIGINT'])
+  def test_pthread_unistd_io(self):
+    self.btest_exit('unistd/io.c', cflags=['-pthread', '-sPROXY_TO_PTHREAD'])
 
   # Test that the main thread is able to use pthread_set/getspecific.
   @also_with_wasm2js
@@ -5264,17 +5262,16 @@ def test_dlmalloc_3gb(self):
       self.set_setting('MAXIMUM_MEMORY', '4GB')
     self.btest_exit('alloc_3gb.c', cflags=['-sMALLOC=dlmalloc', '-sALLOW_MEMORY_GROWTH=1'])
 
+  # under wasm2js we disable BigInt support which affects the ABI
+  @also_with_wasm2js
   @parameterized({
     # the fetch backend works even on the main thread: we proxy to a background
     # thread and busy-wait
     # this test requires one thread per fetch backend, so updates to the test
     # will require bumping this
-    'main_thread': (['-sPTHREAD_POOL_SIZE=5'],),
+    '': (['-sPTHREAD_POOL_SIZE=5'],),
     # using proxy_to_pthread also works, of course
     'proxy_to_pthread': (['-sPROXY_TO_PTHREAD', '-DPROXYING'],),
-    # using BigInt support affects the ABI, and should not break things. (this
-    # could be tested on either thread; do the main thread for simplicity)
-    'bigint': (['-sPTHREAD_POOL_SIZE=5', '-sWASM_BIGINT'],),
   })
   def test_wasmfs_fetch_backend_threaded(self, args):
     create_file('data.dat', 'hello, fetch')
@@ -5290,10 +5287,10 @@ def test_wasmfs_fetch_backend_threaded(self, args):
                             '--js-library', test_file('wasmfs/wasmfs_fetch.js')] + args)
 
   @no_firefox('no OPFS support yet')
+  @also_with_wasm2js
   @parameterized({
     '': (['-pthread', '-sPROXY_TO_PTHREAD'],),
     'jspi': (['-sJSPI'],),
-    'jspi_wasm_bigint': (['-sJSPI', '-sWASM_BIGINT'],),
     'asyncify': (['-sASYNCIFY=1'],),
   })
   @no_safari('TODO: Fails with abort:Assertion failed: err == 0') # Fails in Safari 17.6 (17618.3.11.11.7, 17618), Safari 26.0.1 (21622.1.22.11.15)

test/test_core.py

@@ -48,7 +48,6 @@
   also_with_pthreads,
   also_with_standalone_wasm,
   also_with_wasmfs,
-  also_without_bigint,
   can_do_standalone,
   crossplatform,
   disabled,
@@ -2080,7 +2079,7 @@ def test_em_js(self, args, force_c):
   @no_wasm2js('test depends on WASM_BIGINT which is not compatible with wasm2js')
   def test_em_js_i64(self):
     expected = 'emcc: error: using 64-bit arguments in EM_JS function without WASM_BIGINT is not yet fully supported: `foo`'
-    self.assert_fail([EMCC, '-Werror', '-sWASM_BIGINT=0', test_file('core/test_em_js_i64.c')], expected)
+    self.assert_fail([EMCC, '-Werror', '-sWASM=0', test_file('core/test_em_js_i64.c')], expected)
     self.do_core_test('test_em_js_i64.c')
 
   def test_em_js_address_taken(self):
@@ -4419,7 +4418,6 @@ def test_dylink_i64_b(self):
     ''', 'other says -1311768467750121224.\nmy fp says: 43.\nmy second fp says: 43.', force_c=True)
 
   @with_dylink_reversed
-  @also_without_bigint
   def test_dylink_i64_c(self):
     self.dylink_test(r'''
       #include <stdio.h>
@@ -4471,7 +4469,6 @@ def test_dylink_i64_c(self):
       EMSCRIPTEN_KEEPALIVE int64_t function_ret_64(int32_t i, int32_t j, int32_t k);
     ''', force_c=True)
 
-  @also_without_bigint
   @parameterized({
     '': (False,),
     'rtld_local': (True,),
@@ -5728,7 +5725,6 @@ def test_readdir(self):
       self.cflags += ['-DWASMFS_NODERAWFS']
     self.do_runf_out_file('dirent/test_readdir.c')
 
-  @also_without_bigint
   def test_readdir_empty(self):
     self.do_runf_out_file('dirent/test_readdir_empty.c')
 
@@ -5782,7 +5778,6 @@ def test_fcntl_open(self):
       self.skipTest('noderawfs fails here under non-linux')
     self.do_runf_out_file('fcntl/test_fcntl_open.c')
 
-  @also_without_bigint
   def test_fcntl_misc(self):
     if self.get_setting('WASMFS'):
       self.cflags += ['-sFORCE_FILESYSTEM']
@@ -5860,7 +5855,6 @@ def test_utf8(self):
     self.do_runf('core/test_utf8.c', 'done\n')
 
   @with_both_text_decoder
-  @also_without_bigint
   def test_utf8_bench(self):
     self.cflags += ['--embed-file', test_file('test_utf8_bench.txt') + '@/utf8_corpus.txt']
     self.do_runf('test_utf8_bench.c', 'done\n')
@@ -6304,7 +6298,6 @@ def test_unistd_symlink_on_nodefs(self):
     # Calling readlink() on a non-link gives error 22 EINVAL on Unix, but simply error 0 OK on Windows.
     self.do_runf_out_file('unistd/symlink_on_nodefs.c', cflags=['-lnodefs.js'])
 
-  @also_without_bigint
   @also_with_nodefs
   def test_unistd_io(self):
     if self.get_setting('WASMFS'):
@@ -7269,7 +7262,6 @@ def test_dyncall_ptr_handling(self):
   def test_dyncall_pointers(self, args):
     self.do_core_test('test_dyncall_pointers.c', cflags=args)
 
-  @also_without_bigint
   @no_modularize_instance('uses Module object directly')
   def test_getValue_setValue(self):
     # these used to be exported, but no longer are by default
@@ -7704,7 +7696,6 @@ def test_embind_float_constants(self):
   def test_embind_negative_constants(self):
     self.do_runf_out_file('embind/test_negative_constants.cpp', cflags=['-lembind'])
 
-  @also_without_bigint
   def test_embind_unsigned(self):
     self.do_runf_out_file('embind/test_unsigned.cpp', cflags=['-lembind'])
 
@@ -8242,7 +8233,6 @@ def test_modularize_closure_pre(self):
 
   @no_wasm2js('symbol names look different wasm2js backtraces')
   @no_modularize_instance('assumes .js output filename')
-  @also_without_bigint
   @no_bun('https://github.com/emscripten-core/emscripten/issues/26197')
   def test_emscripten_log(self):
     self.cflags += ['-g', '-DRUN_FROM_JS_SHELL', '-Wno-deprecated-pragma']
@@ -9788,7 +9778,6 @@ def test_pipe_select(self, args):
   def test_pipe_pollhup(self):
     self.do_runf('core/test_pipe_pollhup.c', 'done\n')
 
-  @also_without_bigint
   def test_jslib_i64_params(self):
     # Tests the defineI64Param and receiveI64ParamAsI53 helpers that are
     # used to receive i64 argument in syscalls.

test/test_jslib.py

@@ -6,7 +6,7 @@
 from subprocess import PIPE
 
 from common import RunnerCore, copy_asset, create_file, read_file, test_file
-from decorators import also_with_wasm64, also_without_bigint, parameterized, requires_node_25
+from decorators import also_with_wasm2js, also_with_wasm64, parameterized, requires_node_25
 
 from tools.shared import EMCC
 from tools.utils import delete_file
@@ -375,7 +375,7 @@ def test_jslib_invalid_decorator(self):
                      "lib.js: Decorator (jslibfunc__export) has wrong type. Expected 'boolean' not 'string'")
 
   @also_with_wasm64
-  @also_without_bigint
+  @also_with_wasm2js
   def test_jslib_i53abi(self):
     create_file('lib.js', r'''
 addToLibrary({
@@ -597,7 +597,7 @@ def test_jslib_include(self):
     self.assert_fail([EMCC, test_file('hello_world.c'), '--js-library', 'foo.js'], 'foo.js:5: file not found: inc.js')
 
   @also_with_wasm64
-  @also_without_bigint
+  @also_with_wasm2js
   @parameterized({
     '': ([],),
     'closure': (['--closure=1'],),

test/test_other.py

@@ -71,7 +71,6 @@
   also_with_wasm2js,
   also_with_wasm64,
   also_with_wasmfs,
-  also_without_bigint,
   crossplatform,
   disabled,
   flaky,
@@ -7961,6 +7960,7 @@ def test_EM_ASM_i64(self):
 
   def test_EM_ASM_i64_nobigint(self):
     self.set_setting('WASM_BIGINT', 0)
+    self.cflags.append('-Wno-error=deprecated')
     self.do_runf('other/test_em_asm_i64.cpp', 'Invalid character 106("j") in readEmAsmArgs!', assert_returncode=NON_ZERO)
 
   def test_eval_ctor_ordering(self):
@@ -9471,9 +9471,9 @@ def test_full_js_library_except(self):
   @crossplatform
   @parameterized({
     '': ([],),
-    # bigint support is interesting to test here because it changes which
+    # wasm2js support is interesting to test here because it changes which
     # binaryen tools get run, which can affect how debug info is kept around
-    'nobigint': (['-sWASM_BIGINT=0'],),
+    'wasm2js': (['-sWASM=0'],),
     'pthread': (['-pthread', '-Wno-experimental'],),
     'pthread_offscreen': (['-pthread', '-Wno-experimental', '-sOFFSCREEN_FRAMEBUFFER'],),
     'wasmfs': (['-sWASMFS'],),
@@ -9482,6 +9482,12 @@ def test_full_js_library_except(self):
   })
   def test_closure_full_js_library(self, args):
     # Test for closure errors and warnings in the entire JS library.
+    # Enable as many features as possible in order to maximise
+    # the amount of library code we include here.
+    if '-sWASM=0' in args:
+      args += ['-sEXPORT_ALL']
+    else:
+      args += ['-sMAIN_MODULE']
     self.build('hello_world.c', cflags=[
       '--closure=1',
       '--minify=0',
@@ -9492,9 +9498,6 @@ def test_closure_full_js_library(self, args):
       '-sAUTO_JS_LIBRARIES',
       '-sINCLUDE_FULL_LIBRARY',
       '-sOFFSCREEN_FRAMEBUFFER',
-      # Enable as many features as possible in order to maximise
-      # the amount of library code we include here.
-      '-sMAIN_MODULE',
       '-sFETCH',
       '-sFETCH_SUPPORT_INDEXEDDB',
       '-sLEGACY_GL_EMULATION',
@@ -14103,7 +14106,7 @@ def test_jspi_code_size(self):
   def test_no_cfi(self):
     self.assert_fail([EMCC, '-fsanitize=cfi', '-flto', test_file('hello_world.c')], 'emcc: error: emscripten does not currently support -fsanitize=cfi')
 
-  @also_without_bigint
+  @also_with_wasm2js
   def test_parseTools(self):
     # Suppress js compiler warnings because we deliberately use legacy parseTools functions
     self.cflags += ['-Wno-js-compiler', '--js-library', test_file('other/test_parseTools.js')]
@@ -14355,7 +14358,7 @@ def test_itimer_pthread(self):
     self.do_other_test('test_itimer.c')
 
   def test_itimer_standalone(self):
-    self.do_other_test('test_itimer_standalone.c', cflags=['-sSTANDALONE_WASM', '-sWASM_BIGINT'])
+    self.do_other_test('test_itimer_standalone.c', cflags=['-sSTANDALONE_WASM'])
     for engine in config.WASM_ENGINES:
       print('wasm engine', engine)
       self.assertContained('done\n', self.run_js('test_itimer_standalone.wasm', engine))

tools/settings.py

@@ -109,6 +109,7 @@
 DEPRECATED_SETTINGS = {
     'RUNTIME_LINKED_LIBS': 'you can simply list the libraries directly on the commandline now',
     'CLOSURE_WARNINGS': 'use -Wclosure/-Wno-closure instead',
+    'WASM_BIGINT': 'no longer needed. Should only ever be implicitly disabled by -sWASM=0',
     'ASYNCIFY_EXPORTS': 'please use JSPI_EXPORTS instead',
     'LINKABLE': 'under consideration for removal (https://github.com/emscripten-core/emscripten/issues/25262)',
     'EXPORT_EXCEPTION_HANDLING_HELPERS': 'getExceptionMessage is exported anyway when ASSERTIONS or EXCEPTION_STACK_TRACES is set, which are set by default at -O0. At -O1 or above, you can export it separately by -sEXPORTED_RUNTIME_METHODS=getExceptionMessage,decrementExceptionRefcount.',