Android: Check R8 output for references to missing symbols

javac prevents missing symbols via compiler errors, but they
can still occur by including prebuilts with incomplete deps,
or by using jar_excluded_patterns to remove a class that is
actually used.

Bug: 1142530
Change-Id: Idebb28c9e1133d9021d899c570e35a5ff16d5f14
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2510236
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Peter Kotwicz <pkotwicz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824739}

build/android/gyp/proguard.py

@@ -84,9 +84,9 @@ def _ParseOptions():
       action='store_true',
       help='Disable the outlining optimization provided by R8.')
   parser.add_argument(
-      '--disable-checkdiscard',
-      action='store_true',
-      help='Disable -checkdiscard directives')
+    '--disable-checks',
+    action='store_true',
+    help='Disable -checkdiscard directives and missing symbols check')
   parser.add_argument('--sourcefile', help='Value for source file attribute')
   parser.add_argument(
       '--force-enable-assertions',
@@ -233,14 +233,9 @@ def _OptimizeWithR8(options,
         tmp_mapping_path,
     ]
 
-    if options.disable_checkdiscard:
+    if options.disable_checks:
       # Info level priority logs are not printed by default.
-      cmd += [
-          '--map-diagnostics:'
-          'com.android.tools.r8.errors.CheckDiscardDiagnostic',
-          'error',
-          'info',
-      ]
+      cmd += ['--map-diagnostics:CheckDiscardDiagnostic', 'error', 'info']
 
     if options.desugar_jdk_libs_json:
       cmd += [
@@ -329,6 +324,102 @@ def _OptimizeWithR8(options,
       out_file.writelines(l for l in in_file if not l.startswith('#'))
 
 
+def _CheckForMissingSymbols(r8_path, dex_files, classpath, warnings_as_errors):
+  cmd = build_utils.JavaCmd(warnings_as_errors) + [
+      '-cp', r8_path, 'com.android.tools.r8.tracereferences.TraceReferences',
+      '--map-diagnostics:MissingDefinitionsDiagnostic', 'error', 'warning'
+  ]
+
+  for path in classpath:
+    cmd += ['--lib', path]
+  for path in dex_files:
+    cmd += ['--source', path]
+
+  def stderr_filter(stderr):
+    ignored_lines = [
+        # Summary contains warning count, which our filtering makes wrong.
+        'Warning: Tracereferences found',
+
+        # TODO(agrieve): Create interface jars for these missing classes rather
+        #     than allowlisting here.
+        'dalvik/system',
+        'libcore/io',
+        'sun/misc/Unsafe',
+
+        # Found in: com/facebook/fbui/textlayoutbuilder/StaticLayoutHelper
+        ('android/text/StaticLayout;<init>(Ljava/lang/CharSequence;IILandroid'
+         '/text/TextPaint;ILandroid/text/Layout$Alignment;Landroid/text/'
+         'TextDirectionHeuristic;FFZLandroid/text/TextUtils$TruncateAt;II)V'),
+
+        # Found in
+        # com/google/android/gms/cast/framework/media/internal/ResourceProvider
+        # Missing due to setting "strip_resources = true".
+        'com/google/android/gms/cast/framework/R',
+
+        # Found in com/google/android/gms/common/GoogleApiAvailability
+        # Missing due to setting "strip_drawables = true".
+        'com/google/android/gms/base/R$drawable',
+
+        # Explicictly guarded by try (NoClassDefFoundError) in Flogger's
+        # PlatformProvider.
+        'com/google/common/flogger/backend/google/GooglePlatform',
+        'com/google/common/flogger/backend/system/DefaultPlatform',
+
+        # trichrome_webview_google_bundle contains this missing reference.
+        # TODO(crbug.com/1142530): Fix this missing reference properly.
+        'org/chromium/base/library_loader/NativeLibraries',
+
+        # Currently required when enable_chrome_android_internal=true.
+        'com/google/protos/research/ink/InkEventProto',
+        'ink_sdk/com/google/protobuf/Internal$EnumVerifier',
+        'ink_sdk/com/google/protobuf/MessageLite',
+
+        # Referenced from GeneratedExtensionRegistryLite.
+        # Exists only for Chrome Modern (not Monochrome nor Trichrome).
+        # TODO(agrieve): Figure out why. Perhaps related to Feed V2.
+        ('com/google/wireless/android/play/playlog/proto/ClientAnalytics$'
+         'ClientInfo'),
+
+        # TODO(agrieve): Exclude these only when use_jacoco_coverage=true.
+        'Ljava/lang/instrument/ClassFileTransformer',
+        'Ljava/lang/instrument/IllegalClassFormatException',
+        'Ljava/lang/instrument/Instrumentation',
+        'Ljava/lang/management/ManagementFactory',
+        'Ljavax/management/MBeanServer',
+        'Ljavax/management/ObjectInstance',
+        'Ljavax/management/ObjectName',
+        'Ljavax/management/StandardMBean',
+    ]
+
+    had_unfiltered_items = '  ' in stderr
+    stderr = build_utils.FilterLines(
+        stderr, '|'.join(re.escape(x) for x in ignored_lines))
+    if stderr:
+      if '  ' in stderr:
+        stderr = """
+DEX contains references to non-existent symbols after R8 optimization.
+Tip: Build with:
+        is_java_debug=false
+        treat_warnings_as_errors=false
+        enable_proguard_obfuscation=false
+     and then use dexdump to see which class(s) reference them.
+
+     E.g.:
+       third_party/android_sdk/public/build-tools/*/dexdump -d \
+out/Release/apks/YourApk.apk > dex.txt
+""" + stderr
+      elif had_unfiltered_items:
+        # Left only with empty headings. All indented items filtered out.
+        stderr = ''
+    return stderr
+
+  logging.debug('cmd: %s', ' '.join(cmd))
+  build_utils.CheckOutput(cmd,
+                          print_stdout=True,
+                          stderr_filter=stderr_filter,
+                          fail_on_output=warnings_as_errors)
+
+
 def _CombineConfigs(configs, dynamic_config_data, exclude_generated=False):
   ret = []
 
@@ -458,6 +549,16 @@ def main():
   _OptimizeWithR8(options, proguard_configs, libraries, dynamic_config_data,
                   print_stdout)
 
+  if not options.disable_checks:
+    logging.debug('Running tracereferences')
+    all_dex_files = []
+    if options.output_path:
+      all_dex_files.append(options.output_path)
+    if options.dex_dests:
+      all_dex_files.extend(options.dex_dests)
+    _CheckForMissingSymbols(options.r8_path, all_dex_files, options.classpath,
+                            options.warnings_as_errors)
+
   for output in options.extra_mapping_output_paths:
     shutil.copy(options.mapping_output, output)
 

build/config/android/internal_rules.gni

@@ -1245,8 +1245,9 @@ if (enable_java_templates) {
       _args += [ "--disable-outlining" ]
     }
 
-    if (defined(invoker.disable_checkdiscard) && invoker.disable_checkdiscard) {
-      _args += [ "--disable-checkdiscard" ]
+    if (defined(invoker.enable_proguard_checks) &&
+        !invoker.enable_proguard_checks) {
+      _args += [ "--disable-checks" ]
     }
 
     if (defined(invoker.is_static_library) && invoker.is_static_library) {
@@ -1487,8 +1488,8 @@ if (enable_java_templates) {
                                  "data",
                                  "data_deps",
                                  "deps",
-                                 "disable_checkdiscard",
                                  "disable_r8_outlining",
+                                 "enable_proguard_checks",
                                  "expected_proguard_config",
                                  "expected_proguard_config_base",
                                  "is_static_library",

build/config/android/rules.gni

@@ -2139,8 +2139,8 @@ if (enable_java_templates) {
   #     (optional).
   #   product_config_java_packages: Optional list of java packages. If given, a
   #     ProductConfig.java file will be generated for each package.
-  #   disable_checkdiscard: Turn off -checkdiscard directives in the proguard
-  #     step.
+  #   enable_proguard_checks: Turns on -checkdiscard directives and missing
+  #     symbols check in the proguard step (default=true).
   #   disable_r8_outlining: Turn off outlining during the proguard step.
   #   annotation_processor_deps: List of java_annotation_processor targets to
   #     use when compiling the sources given to this target (optional).
@@ -2387,7 +2387,6 @@ if (enable_java_templates) {
 
     if (_is_static_library_provider) {
       _shared_resources_allowlist_target = _resource_ids_provider_dep
-      disable_checkdiscard = true
     } else if (defined(invoker.shared_resources_allowlist_target)) {
       _shared_resources_allowlist_target =
           invoker.shared_resources_allowlist_target
@@ -2902,8 +2901,8 @@ if (enable_java_templates) {
       if (defined(invoker.negative_main_dex_globs)) {
         not_needed(invoker, [ "negative_main_dex_globs" ])
       }
-      if (defined(invoker.disable_checkdiscard)) {
-        not_needed(invoker, [ "disable_checkdiscard" ])
+      if (defined(invoker.enable_proguard_checks)) {
+        not_needed(invoker, [ "enable_proguard_checks" ])
       }
       if (defined(invoker.disable_r8_outlining)) {
         not_needed(invoker, [ "disable_r8_outlining" ])
@@ -2922,9 +2921,9 @@ if (enable_java_templates) {
       dex(_final_dex_target_name) {
         forward_variables_from(invoker,
                                [
-                                 "disable_checkdiscard",
                                  "disable_r8_outlining",
                                  "dexlayout_profile",
+                                 "enable_proguard_checks",
                                ])
         min_sdk_version = _min_sdk_version
         proguard_enabled = _proguard_enabled
@@ -3477,13 +3476,13 @@ if (enable_java_templates) {
                                "data_deps",
                                "deps",
                                "dexlayout_profile",
-                               "disable_checkdiscard",
                                "disable_r8_outlining",
                                "dist_ijar_path",
                                "enable_lint",
                                "enable_jetify",
                                "enable_multidex",
                                "enable_native_mocks",
+                               "enable_proguard_checks",
                                "enforce_resource_overlays_in_tests",
                                "expected_android_manifest",
                                "expected_android_manifest_base",
@@ -3831,7 +3830,7 @@ if (enable_java_templates) {
         if (defined(invoker.proguard_configs)) {
           proguard_configs += invoker.proguard_configs
         }
-        disable_checkdiscard = true
+        enable_proguard_checks = false
         if (defined(invoker.final_apk_path)) {
           _final_apk_path = final_apk_path
         } else {

components/cronet/android/BUILD.gn

@@ -1188,6 +1188,7 @@ if (!is_component_build) {
         "//base/android/proguard/chromium_apk.flags",
         "//testing/android/proguard_for_test.flags",
       ]
+      enable_proguard_checks = false
     }
   }
 

remoting/android/remoting_apk_tmpl.gni

@@ -13,7 +13,9 @@ template("remoting_apk_tmpl") {
     if (!is_java_debug) {
       proguard_enabled = true
       enable_multidex = false
-      disable_checkdiscard = true
+
+      # -checkdiscard checks fail due to -dontoptimize.
+      enable_proguard_checks = false
       if (!defined(proguard_configs)) {
         proguard_configs = []
       }