do not apply -l if not generating an executable or a library

emcc

@@ -540,6 +540,15 @@ for i in range(len(sys.argv)-1):
     sys.argv = sys.argv[:i] + sys.argv[i+2:]
     break
 
+specified_target = target
+target = specified_target if specified_target is not None else 'a.out.js' # specified_target is the user-specified one, target is what we will generate
+target_basename = unsuffixed_basename(target)
+
+if '.' in target:
+  final_suffix = target.split('.')[-1]
+else:
+  final_suffix = ''
+
 if header: # header or such
   if len(sys.argv) >= 3: # if there is a source and a target, then copy, otherwise do nothing
     sys.argv = filter(lambda arg: not arg.startswith('-I'), sys.argv)
@@ -789,6 +798,17 @@ try:
 
   newargs = [ arg for arg in newargs if arg is not '' ]
 
+  # -c means do not link in gcc, and for us, the parallel is to not go all the way to JS, but stop at bitcode
+  has_dash_c = '-c' in newargs
+  if has_dash_c:
+    assert has_source_inputs, 'Must have source code inputs to use -c'
+    target = target_basename + '.o'
+    final_suffix = 'o'
+
+  # do not link in libs when just generating object code (not an 'executable', i.e. JS, or a library)
+  if ('.' + final_suffix) in BITCODE_SUFFIXES:
+    libs = []
+
   # Find library files
   for lib in libs:
     if DEBUG: print >> sys.stderr, 'emcc: looking for library "%s"' % lib
@@ -816,22 +836,6 @@ try:
 
   newargs += CC_ADDITIONAL_ARGS
 
-  specified_target = target
-  target = specified_target if specified_target is not None else 'a.out.js' # specified_target is the user-specified one, target is what we will generate
-
-  target_basename = unsuffixed_basename(target)
-
-  # -c means do not link in gcc, and for us, the parallel is to not go all the way to JS, but stop at bitcode
-  has_dash_c = '-c' in newargs
-  if has_dash_c:
-    assert has_source_inputs, 'Must have source code inputs to use -c'
-    target = target_basename + '.o'
-
-  if '.' in target:
-    final_suffix = target.split('.')[-1]
-  else:
-    final_suffix = ''
-
   assert not (Compression.on and final_suffix != 'html'), 'Compression only works when generating HTML'
 
   # If we are using embind and generating JS, now is the time to link in bind.cpp
@@ -904,7 +908,7 @@ try:
         assert len(original_input_files) == 1 or not has_dash_c, 'fatal error: cannot specify -o with -c with multiple files' + str(sys.argv) + ':' + str(original_input_files)
         # We have a specified target (-o <target>), which is not JavaScript or HTML, and
         # we have multiple files: Link them
-        if DEBUG: print >> sys.stderr, 'emcc: link: ' + str(temp_files)
+        if DEBUG: print >> sys.stderr, 'emcc: link: ' + str(temp_files), specified_target
         shared.Building.link(temp_files, specified_target, remove_duplicates=remove_duplicates)
     exit(0)
 

tests/runner.py

@@ -7850,6 +7850,36 @@ f.close()
       self.assertContained('hello from lib', run_js(os.path.join(self.get_dir(), 'a.out.js')))
       assert not os.path.exists('a.out') and not os.path.exists('a.exe'), 'Must not leave unneeded linker stubs'
 
+    def test_multiply_defined_libsymbols(self):
+      lib = "int mult() { return 1; }"
+      lib_name = os.path.join(self.get_dir(), 'libA.c')
+      open(lib_name, 'w').write(lib)
+      a2 = "void x() {}"
+      a2_name = os.path.join(self.get_dir(), 'a2.c')
+      open(a2_name, 'w').write(a2)
+      b2 = "void y() {}"
+      b2_name = os.path.join(self.get_dir(), 'b2.c')
+      open(b2_name, 'w').write(b2)
+      main = r'''
+        #include <stdio.h>
+        int mult();
+        int main() {
+          printf("result: %d\n", mult());
+          return 0;
+        }
+      '''
+      main_name = os.path.join(self.get_dir(), 'main.c')
+      open(main_name, 'w').write(main)
+
+      Building.emcc(lib_name, output_filename='libA.so')
+
+      Building.emcc(a2_name, ['-L.', '-lA'])
+      Building.emcc(b2_name, ['-L.', '-lA'])
+
+      Building.emcc(main_name, ['-L.', '-lA', a2_name+'.o', b2_name+'.o'], output_filename='a.out.js')
+
+      self.assertContained('result: 1', run_js(os.path.join(self.get_dir(), 'a.out.js')))
+
     def test_abspaths(self):
       # Includes with absolute paths are generally dangerous, things like -I/usr/.. will get to system local headers, not our portable ones.