Avoid converting user JS library paths to absolute paths. NFC (emscripten-core#23798)

System library paths are converted to absolute paths, both in link.py
and in modules.mjs, but use JS libraries are left in their original
form.

Added a test to confirm that a user library can have the same name as as
system library without issue.

Split out from emscripten-core#23787

Author: sbc100

emcc.py

@@ -1219,7 +1219,6 @@ def consume_arg_file():
         options.memory_profiler = True
       newargs[i] = ''
       settings_changes.append('EMSCRIPTEN_TRACING=1')
-      settings.JS_LIBRARIES.append('libtrace.js')
     elif check_flag('--emit-symbol-map'):
       options.emit_symbol_map = True
       settings.EMIT_SYMBOL_MAP = 1

src/modules.mjs

@@ -5,7 +5,6 @@
  */
 
 import * as path from 'node:path';
-import * as fs from 'node:fs';
 import {fileURLToPath} from 'node:url';
 import assert from 'node:assert';
 
@@ -201,20 +200,15 @@ function calculateLibraries() {
     libraries.push('liblittle_endian_heap.js');
   }
 
+  // Resolve system libraries
+  libraries = libraries.map((filename) => path.join(systemLibdir, filename));
+
   // Add all user specified JS library files to the link.
   // These must be added last after all Emscripten-provided system libraries
   // above, so that users can override built-in JS library symbols in their
   // own code.
   libraries.push(...JS_LIBRARIES);
 
-  // Resolve all filenames to absolute paths
-  libraries = libraries.map((filename) => {
-    if (!path.isAbsolute(filename) && fs.existsSync(path.join(systemLibdir, filename))) {
-      filename = path.join(systemLibdir, filename);
-    }
-    return path.resolve(filename);
-  });
-
   // Deduplicate libraries to avoid processing any library file multiple times
   libraries = libraries.filter((item, pos) => libraries.indexOf(item) == pos);
 

test/test_other.py

@@ -5001,6 +5001,23 @@ def test_jslib_new_objects_non_empty(self):
     err = self.expect_fail([EMCC, test_file('hello_world.c'), '--js-library=lib.js', '-sEXPORTED_FUNCTIONS=obj,_main'])
     self.assertContained('cannot stringify Map with data', err)
 
+  def test_jslib_system_lib_name(self):
+    create_file('libcore.js', r'''
+addToLibrary({
+ jslibfunc: (x) => 2 * x
+});
+''')
+    create_file('src.c', r'''
+#include <emscripten.h>
+#include <stdio.h>
+int jslibfunc(int x);
+int main() {
+  printf("jslibfunc: %d\n", jslibfunc(6));
+  return 0;
+}
+''')
+    self.do_runf('src.c', 'jslibfunc: 12', emcc_args=['--js-library', 'libcore.js'])
+
   def test_EMCC_BUILD_DIR(self):
     # EMCC_BUILD_DIR was necessary in the past since we used to force the cwd to be src/ for
     # technical reasons.

tools/link.py

@@ -217,8 +217,6 @@ def get_js_sym_info():
   assert jslibs
   input_files.extend(read_file(jslib) for jslib in sorted(jslibs))
   for jslib in settings.JS_LIBRARIES:
-    if not os.path.isabs(jslib):
-      jslib = utils.path_from_root('src/lib', jslib)
     input_files.append(read_file(jslib))
   content = '\n'.join(input_files)
   content_hash = hashlib.sha1(content.encode('utf-8')).hexdigest()
@@ -629,6 +627,12 @@ def check_browser_versions():
       exit_with_error(f'{key} older than {oldest} is not supported')
 
 
+def add_system_js_lib(lib):
+  lib = utils.path_from_root('src/lib', lib)
+  assert os.path.exists(lib)
+  settings.JS_LIBRARIES.append(lib)
+
+
 @ToolchainProfiler.profile_block('linker_setup')
 def phase_linker_setup(options, linker_args):  # noqa: C901, PLR0912, PLR0915
   """Future modifications should consider refactoring to reduce complexity.
@@ -1246,7 +1250,7 @@ def phase_linker_setup(options, linker_args):  # noqa: C901, PLR0912, PLR0915
   if settings.WASMFS:
     settings.FILESYSTEM = 1
     settings.SYSCALLS_REQUIRE_FILESYSTEM = 0
-    settings.JS_LIBRARIES.append('libwasmfs.js')
+    add_system_js_lib('libwasmfs.js')
     if settings.ASSERTIONS:
       # used in assertion checks for unflushed content
       settings.REQUIRED_EXPORTS += ['wasmfs_flush']
@@ -1362,14 +1366,14 @@ def phase_linker_setup(options, linker_args):  # noqa: C901, PLR0912, PLR0915
 
   if settings.PTHREADS:
     setup_pthreads()
-    settings.JS_LIBRARIES.append('libpthread.js')
+    add_system_js_lib('libpthread.js')
     if settings.PROXY_TO_PTHREAD:
       settings.PTHREAD_POOL_SIZE_STRICT = 0
       settings.DEFAULT_LIBRARY_FUNCS_TO_INCLUDE += ['$runtimeKeepalivePush']
   else:
     if settings.PROXY_TO_PTHREAD:
       exit_with_error('-sPROXY_TO_PTHREAD requires -pthread to work!')
-    settings.JS_LIBRARIES.append('libpthread_stub.js')
+    add_system_js_lib('libpthread_stub.js')
 
   if settings.MEMORY64:
     # Any "pointers" passed to JS will now be i64's, in both modes.
@@ -1383,7 +1387,7 @@ def phase_linker_setup(options, linker_args):  # noqa: C901, PLR0912, PLR0915
     # set location of Wasm Worker bootstrap JS file
     if settings.WASM_WORKERS == 1:
       settings.WASM_WORKER_FILE = unsuffixed(os.path.basename(target)) + '.ww.js'
-    settings.JS_LIBRARIES.append('libwasm_worker.js')
+    add_system_js_lib('libwasm_worker.js')
 
   # Set min browser versions based on certain settings such as WASM_BIGINT,
   # PTHREADS, AUDIO_WORKLET
@@ -1401,7 +1405,7 @@ def phase_linker_setup(options, linker_args):  # noqa: C901, PLR0912, PLR0915
   if settings.AUDIO_WORKLET:
     if settings.AUDIO_WORKLET == 1:
       settings.AUDIO_WORKLET_FILE = unsuffixed(os.path.basename(target)) + '.aw.js'
-    settings.JS_LIBRARIES.append('libwebaudio.js')
+    add_system_js_lib('libwebaudio.js')
     if not settings.MINIMAL_RUNTIME:
       # If we are in the audio worklet environment, we can only access the Module object
       # and not the global scope of the main JS script. Therefore we need to export
@@ -1774,11 +1778,13 @@ def get_full_import_name(name):
   if not js_manipulation.isidentifier(settings.EXPORT_NAME):
     exit_with_error(f'EXPORT_NAME is not a valid JS identifier: `{settings.EXPORT_NAME}`')
 
-  if settings.EMSCRIPTEN_TRACING and settings.ALLOW_MEMORY_GROWTH:
-    settings.DEFAULT_LIBRARY_FUNCS_TO_INCLUDE += ['emscripten_trace_report_memory_layout']
-    settings.REQUIRED_EXPORTS += ['emscripten_stack_get_current',
-                                  'emscripten_stack_get_base',
-                                  'emscripten_stack_get_end']
+  if settings.EMSCRIPTEN_TRACING:
+    add_system_js_lib('libtrace.js')
+    if settings.ALLOW_MEMORY_GROWTH:
+      settings.DEFAULT_LIBRARY_FUNCS_TO_INCLUDE += ['emscripten_trace_report_memory_layout']
+      settings.REQUIRED_EXPORTS += ['emscripten_stack_get_current',
+                                    'emscripten_stack_get_base',
+                                    'emscripten_stack_get_end']
 
   settings.EMSCRIPTEN_VERSION = utils.EMSCRIPTEN_VERSION
   settings.SOURCE_MAP_BASE = options.source_map_base or ''
@@ -1999,11 +2005,11 @@ def run_embind_gen(options, wasm_target, js_syms, extra_settings):
   setup_environment_settings()
   # Use a separate Wasm file so the JS does not need to be modified after emscripten.emscript.
   settings.SINGLE_FILE = False
-  # Embind may be included multiple times, de-duplicate the list first.
-  settings.JS_LIBRARIES = dedup_list(settings.JS_LIBRARIES)
   # Replace embind with the TypeScript generation version.
-  embind_index = settings.JS_LIBRARIES.index('libembind.js')
-  settings.JS_LIBRARIES[embind_index] = 'libembind_gen.js'
+  for i, lib in enumerate(settings.JS_LIBRARIES):
+    dirname, basename = os.path.split(lib)
+    if basename == 'libembind.js':
+      settings.JS_LIBRARIES[i] = os.path.join(dirname, 'libembind_gen.js')
   if settings.MEMORY64:
     settings.MIN_NODE_VERSION = 160000
   # Source maps haven't been generated yet and aren't needed to run embind_gen.
@@ -2774,7 +2780,7 @@ def process_libraries(options, flags):
   # Process `-l` and `--js-library` flags
   for flag in flags:
     if flag.startswith('--js-library='):
-      js_lib = os.path.abspath(flag.split('=', 1)[1])
+      js_lib = flag.split('=', 1)[1]
       settings.JS_LIBRARIES.append(js_lib)
       continue
     if not flag.startswith('-l'):
@@ -2786,7 +2792,8 @@ def process_libraries(options, flags):
 
     js_libs = map_to_js_libs(lib)
     if js_libs is not None:
-      settings.JS_LIBRARIES += js_libs
+      for l in js_libs:
+        add_system_js_lib(l)
 
     # We don't need to resolve system libraries to absolute paths here, we can just
     # let wasm-ld handle that.  However, we do want to map to the correct variant.

tools/maint/gen_sig_info.py

@@ -318,6 +318,7 @@ def extract_sig_info(sig_info, extra_settings=None, extra_cflags=None, cxx=False
   }
   if extra_settings:
     settings.update(extra_settings)
+  settings['JS_LIBRARIES'] = [os.path.join(utils.path_from_root('src/lib'), s) for s in settings['JS_LIBRARIES']]
   with tempfiles.get_file('.json') as settings_json:
     utils.write_file(settings_json, json.dumps(settings))
     output = shared.run_js_tool(utils.path_from_root('tools/compiler.mjs'),