Fix for -lGL + AUTO_NATIVE_LIBRARIES=0

When calling `map_to_js_libs('GL')` we were mapping this to the JS
libraries, and not also including the native `libgl` library.  Normally
this doesn't matter since `libgl` is normally included by default but
not when `AUTO_NATIVE_LIBRARIES=0` is used.

This also happens to fix an old bug (#10171) where we would look on the
file system for `libGL.a` before looking in `map_to_js_libs`.

Fixes: #10171
Fixes: #14335

Author: sbc100

emcc.py

@@ -3507,31 +3507,45 @@ def find_library(lib, lib_dirs):
   return None
 
 
+def find_library_shortname(lib, lib_dirs):
+  suffixes = STATICLIB_ENDINGS + DYNAMICLIB_ENDINGS
+
+  for suff in suffixes:
+    name = 'lib' + lib + suff
+    path = find_library(name, lib_dirs)
+    if path:
+      return path
+
+  return None
+
+
 def process_libraries(libs, lib_dirs, linker_inputs):
   libraries = []
   consumed = []
-  suffixes = STATICLIB_ENDINGS + DYNAMICLIB_ENDINGS
 
   # Find library files
   for i, lib in libs:
     logger.debug('looking for library "%s"', lib)
 
-    path = None
-    for suff in suffixes:
-      name = 'lib' + lib + suff
-      path = find_library(name, lib_dirs)
-      if path:
-        break
-
-    if path:
-      linker_inputs.append((i, path))
+    js_libs, native_lib = building.map_to_js_libs(lib)
+    if js_libs is not None:
+      libraries += [(i, js_lib) for js_lib in js_libs]
+      consumed.append(i)
+      # If native_lib is returned then proceed to look that
+      # up using `find_library` below.
+      # TODO(sbc): We should be able to remove
+      # settings.AUTO_NATIVE_LIBRARIES part of this condition once
+      # we fix: https://github.com/emscripten-core/emscripten/issues/14341
+      if native_lib and not settings.AUTO_NATIVE_LIBRARIES:
+        path = find_library_shortname(native_lib, lib_dirs)
+        if path:
+          linker_inputs.append((i, path))
+    elif building.map_and_apply_to_settings(lib):
       consumed.append(i)
     else:
-      jslibs = building.map_to_js_libs(lib)
-      if jslibs is not None:
-        libraries += [(i, jslib) for jslib in jslibs]
-        consumed.append(i)
-      elif building.map_and_apply_to_settings(lib):
+      path = find_library_shortname(lib, lib_dirs)
+      if path:
+        linker_inputs.append((i, path))
         consumed.append(i)
 
   settings.SYSTEM_JS_LIBRARIES += libraries

tests/other/test_explict_gl_linking.c

@@ -0,0 +1,5 @@
+#include <EGL/egl.h>
+
+int main() {
+    return (int)eglGetProcAddress("foo");
+}

tests/test_other.py

@@ -35,7 +35,7 @@
 from runner import RunnerCore, path_from_root, is_slow_test, ensure_dir, disabled, make_executable
 from runner import env_modify, no_mac, no_windows, requires_native_clang, with_env_modify
 from runner import create_file, parameterized, NON_ZERO, node_pthreads, TEST_ROOT, test_file
-from runner import compiler_for, read_file, read_binary
+from runner import compiler_for, read_file, read_binary, EMBUILDER
 from tools import shared, building, utils, deps_info
 import jsrun
 import clang_native
@@ -10607,3 +10607,8 @@ def test_no_deprecated(self):
   def test_bad_export_name(self):
     err = self.expect_fail([EMCC, '-sEXPORT_NAME=foo bar', test_file('hello_world.c')])
     self.assertContained('error: EXPORT_NAME is not a valid JS identifier: `foo bar`', err)
+
+  def test_explict_gl_linking(self):
+    # ensure libgl exists
+    self.run_process([EMBUILDER, 'build', 'libgl'])
+    self.run_process([EMCC, test_file('other/test_explict_gl_linking.c'), '-sNO_AUTO_NATIVE_LIBRARIES', '-lGL'])

tools/building.py

@@ -1339,7 +1339,6 @@ def is_wasm_dylib(filename):
 def map_to_js_libs(library_name):
   # Some native libraries are implemented in Emscripten as system side JS libraries
   library_map = {
-    'c': [],
     'dl': [],
     'EGL': ['library_egl.js'],
     'GL': ['library_webgl.js', 'library_html5_webgl.js'],
@@ -1357,20 +1356,23 @@ def map_to_js_libs(library_name):
     'pthread': [],
     'X11': ['library_xlib.js'],
     'SDL': ['library_sdl.js'],
-    'stdc++': [],
     'uuid': ['library_uuid.js'],
     'websocket': ['library_websocket.js']
   }
+  # And some are hybrid and require JS and native libraries to be included
+  native_library_map = {
+    'GL': 'gl',
+  }
 
   if library_name in library_map:
     libs = library_map[library_name]
     logger.debug('Mapping library `%s` to JS libraries: %s' % (library_name, libs))
-    return libs
+    return (libs, native_library_map.get(library_name))
 
   if library_name.endswith('.js') and os.path.isfile(path_from_root('src', 'library_' + library_name)):
-    return ['library_' + library_name]
+    return (['library_' + library_name], None)
 
-  return None
+  return (None, None)
 
 
 # Map a linker flag to a settings. This lets a user write -lSDL2 and it will have the same effect as