don't link in invalid object files, even if we are force-including all object files (e.g. because the input is a sole .a file, so we want it all); a .a may contain metadata or other stuff we should ignore (#5777)

Author: kripken

tests/test_other.py

@@ -5463,6 +5463,18 @@ def test_link_with_a_static(self):
       Popen([PYTHON, EMCC, 'z.o', 'libtest.a'] + args).communicate()
       out = run_js('a.out.js', assert_returncode=161)
 
+  def test_link_with_bad_o_in_a(self):
+    # when building a .a, we force-include all the objects inside it. but, some
+    # may not be valid bitcode, e.g. if it contains metadata or something else
+    # weird. we should just ignore those
+    subprocess.check_call([PYTHON, EMCC, path_from_root('tests', 'hello_world.c'), '-o', 'a.bc'])
+    open('bad.bc', 'w').write('this is not a good file, it should be ignored!')
+    subprocess.check_call([LLVM_AR, 'r', 'a.a', 'a.bc', 'bad.bc'])
+    assert os.path.exists('a.a')
+    subprocess.check_call([PYTHON, EMCC, 'a.a'])
+    assert os.path.exists('a.out.js'), output
+    self.assertContained('hello, world!', run_js('a.out.js'))
+
   def test_require(self):
     inname = path_from_root('tests', 'hello_world.c')
     Building.emcc(inname, output_filename='a.out.js')

tools/shared.py

@@ -1297,6 +1297,9 @@ def __init__(self, returncode, output, defs=set(), undefs=set(), commons=set()):
     self.undefs = undefs
     self.commons = commons
 
+  def is_valid(self):
+    return self.returncode == 0
+
 # Due to a python pickling issue, the following two functions must be at top level, or multiprocessing pool spawn won't find them.
 
 def g_llvm_nm_uncached(filename):
@@ -1736,6 +1739,9 @@ def link(files, target, force_archive_contents=False, temp_files=None, just_calc
     # returns True.
     def consider_object(f, force_add=False):
       new_symbols = Building.llvm_nm(f)
+      if not new_symbols.is_valid():
+        logging.warning('object %s is not valid, cannot link' % (f))
+        return False
       provided = new_symbols.defs.union(new_symbols.commons)
       do_add = force_add or not unresolved_symbols.isdisjoint(provided)
       if do_add: