Cleanup zlib tests. NFC (#16903)

Use `get_zlib_library` in both tests.

Document all `-W` flags and remove unnecessary ones.

Author: sbc100

tests/common.py

@@ -1227,15 +1227,23 @@ def get_poppler_library(self, env_init=None):
 
     return poppler + freetype
 
-  def get_zlib_library(self):
-    # TODO: remove -Wno-unknown-warning-option when clang rev 11da1b53 rolls into emscripten
-    self.emcc_args += ['-Wno-deprecated-non-prototype', '-Wno-unknown-warning-option']
-    if WINDOWS:
-      return self.get_library(os.path.join('third_party', 'zlib'), os.path.join('libz.a'),
-                              configure=['cmake', '.'],
-                              make=['cmake', '--build', '.'],
-                              make_args=[])
-    return self.get_library(os.path.join('third_party', 'zlib'), os.path.join('libz.a'), make_args=['libz.a'])
+  def get_zlib_library(self, cmake):
+    assert cmake or not WINDOWS, 'on windows, get_zlib_library only supports cmake'
+
+    old_args = self.emcc_args.copy()
+    # inflate.c does -1L << 16
+    self.emcc_args.append('-Wno-shift-negative-value')
+    # adler32.c uses K&R sytyle function declarations
+    self.emcc_args.append('-Wno-deprecated-non-prototype')
+    if cmake:
+      rtn = self.get_library(os.path.join('third_party', 'zlib'), os.path.join('libz.a'),
+                             configure=['cmake', '.'],
+                             make=['cmake', '--build', '.', '--'],
+                             make_args=[])
+    else:
+      rtn = self.get_library(os.path.join('third_party', 'zlib'), os.path.join('libz.a'), make_args=['libz.a'])
+    self.emcc_args = old_args
+    return rtn
 
 
 # Run a server and a web page. When a test runs, we tell the server about it,

tests/test_core.py

@@ -4920,9 +4920,11 @@ def test_dylink_spaghetti(self):
   @needs_make('mingw32-make')
   @needs_dylink
   def test_dylink_zlib(self):
-    self.emcc_args += ['-Wno-shift-negative-value', '-I' + test_file('third_party/zlib')]
     self.set_setting('RELOCATABLE')
-    zlib_archive = self.get_zlib_library()
+    zlib_archive = self.get_zlib_library(cmake=WINDOWS)
+    # example.c uses K&R style function declarations
+    self.emcc_args.append('-Wno-deprecated-non-prototype')
+    self.emcc_args.append('-I' + test_file('third_party/zlib'))
     self.dylink_test(main=read_file(test_file('third_party/zlib/example.c')),
                      side=zlib_archive,
                      expected=read_file(test_file('core/test_zlib.out')),
@@ -6579,27 +6581,18 @@ def test_zlib(self, use_cmake):
       self.skipTest("Windows cannot run configure sh scripts")
 
     self.maybe_closure()
-
-    self.emcc_args.append('-Wno-shift-negative-value')
-    self.emcc_args.append('-Wno-pointer-sign')
-
     if '-g' in self.emcc_args:
       self.emcc_args.append('-gsource-map') # more source maps coverage
 
-    if use_cmake:
-      make_args = []
-      configure = ['cmake', '.']
-    else:
-      make_args = ['libz.a']
-      configure = ['sh', './configure']
+    zlib = self.get_zlib_library(use_cmake)
 
-    # TODO: remove Wno-unknown-warning-option when clang rev 11da1b53 rolls into emscripten
-    self.emcc_args += ['-Wno-deprecated-non-prototype', '-Wno-unknown-warning-option']
+    # example.c uses K&R style function declarations
+    self.emcc_args += ['-Wno-deprecated-non-prototype']
     self.do_run_from_file(
         test_file('third_party/zlib/example.c'),
         test_file('core/test_zlib.out'),
-        libraries=self.get_library('third_party/zlib', 'libz.a', make_args=make_args, configure=configure),
-        includes=[test_file('third_party/zlib'), 'building', 'zlib'])
+        libraries=zlib,
+        includes=[test_file('third_party/zlib')])
 
   @needs_make('make')
   @is_slow_test