Remove code for automatically adding archive indexes (#21121)

Now that wasm-ld no longer requires and index this code is no longer
needed.

Author: sbc100

site/source/docs/tools_reference/settings_reference.rst

@@ -1467,7 +1467,6 @@ Changes enabled by this:
   - IGNORE_MISSING_MAIN is disabled.
   - AUTO_JS_LIBRARIES is disabled.
   - AUTO_NATIVE_LIBRARIES is disabled.
-  - AUTO_ARCHIVE_INDEXES is disabled.
   - DEFAULT_TO_CXX is disabled.
   - USE_GLFW is set to 0 rather than 2 by default.
   - ALLOW_UNIMPLEMENTED_SYSCALLS is disabled.
@@ -1485,16 +1484,6 @@ If this is disabled then one must provide a ``main`` symbol or explicitly
 opt out by passing ``--no-entry`` or an EXPORTED_FUNCTIONS list that doesn't
 include ``_main``.
 
-.. _auto_archive_indexes:
-
-AUTO_ARCHIVE_INDEXES
-====================
-
-Automatically attempt to add archive indexes at link time to archives that
-don't already have them.  This can happen when GNU ar or GNU ranlib is used
-rather than ``llvm-ar`` or ``emar`` since the former don't understand the wasm
-object format.
-
 .. _strict_js:
 
 STRICT_JS

src/settings.js

@@ -1153,7 +1153,6 @@ var LINKABLE = false;
 //   - IGNORE_MISSING_MAIN is disabled.
 //   - AUTO_JS_LIBRARIES is disabled.
 //   - AUTO_NATIVE_LIBRARIES is disabled.
-//   - AUTO_ARCHIVE_INDEXES is disabled.
 //   - DEFAULT_TO_CXX is disabled.
 //   - USE_GLFW is set to 0 rather than 2 by default.
 //   - ALLOW_UNIMPLEMENTED_SYSCALLS is disabled.
@@ -1168,13 +1167,6 @@ var STRICT = false;
 // [link]
 var IGNORE_MISSING_MAIN = true;
 
-// Automatically attempt to add archive indexes at link time to archives that
-// don't already have them.  This can happen when GNU ar or GNU ranlib is used
-// rather than ``llvm-ar`` or ``emar`` since the former don't understand the wasm
-// object format.
-// [link]
-var AUTO_ARCHIVE_INDEXES = true;
-
 // Add ``"use strict;"`` to generated JS
 // [link]
 var STRICT_JS = false;
@@ -2188,4 +2180,5 @@ var LEGACY_SETTINGS = [
   ['MIN_EDGE_VERSION', [0x7FFFFFFF], 'No longer supported'],
   ['MIN_IE_VERSION', [0x7FFFFFFF], 'No longer supported'],
   ['WORKAROUND_OLD_WEBGL_UNIFORM_UPLOAD_IGNORED_OFFSET_BUG', [0], 'No longer supported'],
+  ['AUTO_ARCHIVE_INDEXES', [0, 1], 'No longer needed'],
 ];

test/test_other.py

@@ -9121,22 +9121,6 @@ def test_response_file_bom(self):
     create_file('test.rsp', b'\xef\xbb\xbf--version', binary=True)
     self.run_process([EMCC, '@test.rsp'])
 
-  def test_archive_empty(self):
-    # This test added because we had an issue with the AUTO_ARCHIVE_INDEXES failing on empty
-    # archives (which inherently don't have indexes).
-    self.run_process([EMAR, 'crS', 'libfoo.a'])
-    self.run_process([EMCC, '-Werror', 'libfoo.a', test_file('hello_world.c')])
-
-  def test_archive_no_index(self):
-    create_file('foo.c', 'int foo = 1;')
-    self.run_process([EMCC, '-c', 'foo.c'])
-    self.run_process([EMCC, '-c', test_file('hello_world.c')])
-    # The `S` flag means don't add an archive index
-    self.run_process([EMAR, 'crS', 'libfoo.a', 'foo.o'])
-    # wasm-ld supports archive files without an index (unlike GNU ld) as of
-    # https://github.com/llvm/llvm-project/pull/78821
-    self.run_process([EMCC, 'libfoo.a', 'hello_world.o'])
-
   def test_archive_non_objects(self):
     create_file('file.txt', 'test file')
     self.run_process([EMCC, '-c', test_file('hello_world.c')])

tools/link.py

@@ -35,7 +35,7 @@
 from . import webassembly
 from .utils import read_file, read_binary, write_file, delete_file
 from .utils import removeprefix, exit_with_error
-from .shared import in_temp, safe_copy, do_replace, run_process, OFormat
+from .shared import in_temp, safe_copy, do_replace, OFormat
 from .shared import DEBUG, WINDOWS, DYNAMICLIB_ENDINGS, STATICLIB_ENDINGS
 from .shared import unsuffixed, unsuffixed_basename, get_file_suffix
 from .settings import settings, default_setting, user_settings, JS_ONLY_SETTINGS
@@ -201,38 +201,6 @@ def embed_memfile(options):
             not settings.GENERATE_SOURCE_MAP)))
 
 
-def is_ar_file_with_missing_index(archive_file):
-  # We parse the archive header outselves because llvm-nm --print-armap is slower and less
-  # reliable.
-  # See: https://github.com/emscripten-core/emscripten/issues/10195
-  archive_header = b'!<arch>\n'
-  file_header_size = 60
-
-  with open(archive_file, 'rb') as f:
-    header = f.read(len(archive_header))
-    if header != archive_header:
-      # This is not even an ar file
-      return False
-    file_header = f.read(file_header_size)
-    if len(file_header) != file_header_size:
-      # We don't have any file entires at all so we don't consider the index missing
-      return False
-
-  name = file_header[:16].strip()
-  # If '/' is the name of the first file we have an index
-  return name != b'/'
-
-
-def ensure_archive_index(archive_file):
-  # Fastcomp linking works without archive indexes.
-  if not settings.AUTO_ARCHIVE_INDEXES:
-    return
-  if is_ar_file_with_missing_index(archive_file):
-    diagnostics.warning('emcc', '%s: archive is missing an index; Use emar when creating libraries to ensure an index is created', archive_file)
-    diagnostics.warning('emcc', '%s: adding index', archive_file)
-    run_process([shared.LLVM_RANLIB, archive_file])
-
-
 def generate_js_sym_info():
   # Runs the js compiler to generate a list of all symbols available in the JS
   # libraries.  This must be done separately for each linker invokation since the
@@ -903,7 +871,6 @@ def phase_linker_setup(options, state, newargs):
     default_setting('DEFAULT_TO_CXX', 0)
     default_setting('AUTO_JS_LIBRARIES', 0)
     default_setting('AUTO_NATIVE_LIBRARIES', 0)
-    default_setting('AUTO_ARCHIVE_INDEXES', 0)
     default_setting('IGNORE_MISSING_MAIN', 0)
     default_setting('ALLOW_UNIMPLEMENTED_SYSCALLS', 0)
     if options.oformat == OFormat.HTML and options.shell_path == DEFAULT_SHELL_HTML:
@@ -2696,10 +2663,6 @@ def process_libraries(state, linker_inputs):
   settings.JS_LIBRARIES = [lib[1] for lib in settings.JS_LIBRARIES]
   state.link_flags = new_flags
 
-  for _, f in linker_inputs:
-    if building.is_ar(f):
-      ensure_archive_index(f)
-
 
 class ScriptSource:
   def __init__(self):