Skip the search for dynamic libraries when static library exists (#23593)

This is a fix for a regression caused by #23336.  

Prior to #23336 all `-l` flags were expanded by emcc to full filenames,
with `.a` files being searched for first. After #23336 we only expand
the the paths of fake shared libraries which wasm-ld itself don't look
for.

Fixes: #23591

Author: sbc100

test/test_other.py

@@ -6736,7 +6736,7 @@ def test(args, be_clean):
       if be_clean:
         assert len(clutter) == 0, 'should not leave clutter ' + str(clutter)
       else:
-         assert len(clutter) == 2, 'should leave .o files'
+        assert len(clutter) == 2, 'should leave .o files'
     test(['-o', 'c.so', '-r'], True)
     test(['-o', 'c.js'], True)
     test(['-o', 'c.html'], True)
@@ -9322,6 +9322,20 @@ def test_side_module_folder_deps(self):
     self.run_process([EMCC, test_file('hello_world.c'), '-sSIDE_MODULE', '-o', 'subdir/libside2.so', '-L', 'subdir', '-lside1'])
     self.run_process([EMCC, test_file('hello_world.c'), '-sMAIN_MODULE', '-o', 'main.js', '-L', 'subdir', '-lside2'])
 
+  @crossplatform
+  def test_side_module_ignore(self):
+    self.run_process([EMCC, test_file('hello_world.c'), '-sSIDE_MODULE', '-o', 'libside.so'])
+
+    # Attempting to link statically against a side module (libside.so) should fail.
+    err = self.expect_fail([EMCC, '-L.', '-lside'])
+    self.assertContained('error: attempted static link of dynamic object ./libside.so', err)
+
+    # But a static library in the same location (libside.a) should take precedence.
+    self.run_process([EMCC, test_file('hello_world.c'), '-c'])
+    self.run_process([EMAR, 'cr', 'libside.a', 'hello_world.o'])
+    self.run_process([EMCC, '-L.', '-lside'])
+    self.assertContained('hello, world!', self.run_js('a.out.js'))
+
   @is_slow_test
   @parameterized({
     '': ([],),

tools/link.py

@@ -2821,7 +2821,8 @@ def process_libraries(state):
       settings.JS_LIBRARIES.append(os.path.abspath(path))
       continue
 
-    if not settings.RELOCATABLE:
+    static_lib = f'lib{lib}.a'
+    if not settings.RELOCATABLE and not find_library(static_lib, state.lib_dirs):
       # Normally we can rely on the native linker to expand `-l` args.
       # However, emscripten also supports `.so` files that are actually just
       # regular object file.  This means we need to support `.so` files even