Remove most Objective-C dbg and opt compiler flags

Currently, Bazel sticks some extra compiler flags in when you compile
Objective-C in dbg or opt mode. These flags should really be set in a
CROSSTOOL rather than in the Bazel core, so remove them.

RELNOTES:
Bazel uses fewer compiler flags by default when building Objective-C. In
particular, Bazel no longer sets `-O0`, `-DDEBUG=1`,
`-fstack-protector`, `-fstack-protector-all`, or `-g` in dbg mode, and
Bazel no longer sets `-Os`, `-DNDEBUG=1`, `-Wno-unused-variable`,
`-Winit-self`, or `-Wno-extra` in opt mode. If you want to apply these
flags to your project, you can reenable them in your CROSSTOOL.
PiperOrigin-RevId: 305065752

src/main/java/com/google/devtools/build/lib/rules/objc/ObjcConfiguration.java

@@ -33,19 +33,10 @@
 public class ObjcConfiguration extends BuildConfiguration.Fragment
     implements ObjcConfigurationApi<PlatformType> {
   @VisibleForTesting
-  static final ImmutableList<String> DBG_COPTS =
-      ImmutableList.of("-O0", "-DDEBUG=1", "-fstack-protector", "-fstack-protector-all", "-g");
-
-  @VisibleForTesting
   static final ImmutableList<String> GLIBCXX_DBG_COPTS =
       ImmutableList.of(
           "-D_GLIBCXX_DEBUG", "-D_GLIBCXX_DEBUG_PEDANTIC", "-D_GLIBCPP_CONCEPT_CHECKS");
 
-  @VisibleForTesting
-  static final ImmutableList<String> OPT_COPTS =
-      ImmutableList.of(
-          "-Os", "-DNDEBUG=1", "-Wno-unused-variable", "-Winit-self", "-Wno-extra");
-
   private final DottedVersion iosSimulatorVersion;
   private final String iosSimulatorDevice;
   private final DottedVersion watchosSimulatorVersion;
@@ -180,17 +171,14 @@ public ImmutableList<String> getCoptsForCompilationMode() {
     switch (compilationMode) {
       case DBG:
         if (this.debugWithGlibcxx) {
-          return ImmutableList.<String>builder()
-              .addAll(DBG_COPTS)
-              .addAll(GLIBCXX_DBG_COPTS)
-              .build();
+          return GLIBCXX_DBG_COPTS;
         } else {
-          return DBG_COPTS;
+          return ImmutableList.of();
         }
       case FASTBUILD:
         return fastbuildOptions;
       case OPT:
-        return OPT_COPTS;
+        return ImmutableList.of();
       default:
         throw new AssertionError();
     }

src/test/java/com/google/devtools/build/lib/rules/objc/ObjcRuleTestCase.java

@@ -237,20 +237,6 @@ private static String compilationModeFlag(CompilationMode mode) {
     throw new AssertionError();
   }
 
-  private static List<String> compilationModeCopts(CompilationMode mode) {
-    switch (mode) {
-      case DBG:
-        return ImmutableList.<String>builder()
-            .addAll(ObjcConfiguration.DBG_COPTS)
-            .build();
-      case OPT:
-        return ObjcConfiguration.OPT_COPTS;
-      case FASTBUILD:
-        return FASTBUILD_COPTS;
-    }
-    throw new AssertionError();
-  }
-
   @Override
   protected void useConfiguration(String... args) throws Exception {
     ImmutableList<String> extraArgs = MockObjcSupport.requiredObjcCrosstoolFlags();
@@ -972,9 +958,8 @@ protected void checkErrorsWrongFileTypeForSrcsWhenCompiling(RuleType ruleType)
 
   protected void checkClangCoptsForCompilationMode(RuleType ruleType, CompilationMode mode,
       CodeCoverageMode codeCoverageMode) throws Exception {
-    ImmutableList.Builder<String> allExpectedCoptsBuilder = ImmutableList.<String>builder()
-        .addAll(CompilationSupport.DEFAULT_COMPILER_FLAGS)
-        .addAll(compilationModeCopts(mode));
+    ImmutableList.Builder<String> allExpectedCoptsBuilder =
+        ImmutableList.<String>builder().addAll(CompilationSupport.DEFAULT_COMPILER_FLAGS);
 
     switch (codeCoverageMode) {
       case NONE:
@@ -1008,9 +993,8 @@ protected void checkClangCoptsForCompilationMode(RuleType ruleType, CompilationM
   }
 
   protected void checkClangCoptsForDebugModeWithoutGlib(RuleType ruleType) throws Exception {
-     ImmutableList.Builder<String> allExpectedCoptsBuilder = ImmutableList.<String>builder()
-        .addAll(CompilationSupport.DEFAULT_COMPILER_FLAGS)
-        .addAll(ObjcConfiguration.DBG_COPTS);
+    ImmutableList.Builder<String> allExpectedCoptsBuilder =
+        ImmutableList.<String>builder().addAll(CompilationSupport.DEFAULT_COMPILER_FLAGS);
 
     useConfiguration(
         "--apple_platform_type=ios", "--compilation_mode=dbg", "--objc_debug_with_GLIBCXX=false");

src/test/java/com/google/devtools/build/lib/rules/objc/ObjcSkylarkTest.java

@@ -812,15 +812,12 @@ public void testSkylarkCanAccessObjcConfiguration() throws Exception {
 
     @SuppressWarnings("unchecked")
     List<String> copts = (List<String>) myInfo.getValue("copts");
-    @SuppressWarnings("unchecked")
-    List<String> compilationModeCopts = (List<String>) myInfo.getValue("compilation_mode_copts");
     Object iosSimulatorDevice = myInfo.getValue("ios_simulator_device");
     Object iosSimulatorVersion = myInfo.getValue("ios_simulator_version");
     Object signingCertificateName = myInfo.getValue("signing_certificate_name");
     Boolean generateDsym = (Boolean) myInfo.getValue("generate_dsym");
 
     assertThat(copts).contains("-DTestObjcCopt");
-    assertThat(compilationModeCopts).containsExactlyElementsIn(ObjcConfiguration.OPT_COPTS);
     assertThat(iosSimulatorDevice).isEqualTo("'iPhone 6'");
     assertThat(iosSimulatorVersion).isEqualTo("8.4");
     assertThat(signingCertificateName).isEqualTo("'Apple Developer'");