Fixes for C++20 support.

* Structs with user-declared constructors are no longer aggregates.
  Delete the declarations.
* u8"" no longer produces const char*.  Change to "", which also accepts
  UTF-8 literals.  This requires a few follow-on conversions/casts.
* Math between disparate enums is deprecated.  Use constexprs.
* Various algorithms' lambdas must fit tighter constraints.  Add consts.
* Remove some unnecessary qualifications in preparations for later
  constexpr changes.
* std::iterator is removed.  Expose the type aliases directly.
* Types on both sides of comparison operators should be the same.

Bug: 1284275
Change-Id: Icaed9c2ec7d914cc5aba156133ea34152d8ca606
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3632589
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Reviewed-by: Ted Choc <tedchoc@chromium.org>
Auto-Submit: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1001773}

components/autofill/core/browser/form_data_importer.h

@@ -138,10 +138,6 @@ class FormDataImporter {
     // Metadata about the import, used for metric collection in
     // ProfileImportProcess after the user's decision.
     ProfileImportMetadata import_metadata;
-    AddressProfileImportCandidate(AddressProfileImportCandidate&& other) =
-        default;
-    AddressProfileImportCandidate& operator=(
-        AddressProfileImportCandidate&& other) = default;
   };
 
   // Scans the given |form| for importable Autofill data. If the form includes

components/autofill/core/browser/payments/card_unmask_challenge_option.h

@@ -21,12 +21,6 @@ enum class CardUnmaskChallengeOptionType {
 // The struct used by Autofill components to represent a card unmask challenge
 // option.
 struct CardUnmaskChallengeOption {
-  CardUnmaskChallengeOption() = default;
-  CardUnmaskChallengeOption(const CardUnmaskChallengeOption&) = default;
-  ~CardUnmaskChallengeOption() = default;
-  CardUnmaskChallengeOption& operator=(const CardUnmaskChallengeOption&) =
-      default;
-
   // The unique identifier for the challenge option.
   std::string id = std::string();
 

components/autofill/core/browser/payments/credit_card_fido_authenticator.h

@@ -65,9 +65,6 @@ class CreditCardFIDOAuthenticator
   // The response of FIDO authentication, including necessary information needed
   // by the subclasses.
   struct FidoAuthenticationResponse {
-    FidoAuthenticationResponse() = default;
-    ~FidoAuthenticationResponse() = default;
-
     // Whether the authentication was successful.
     bool did_succeed = false;
     // The fetched credit card if the authentication was successful. Can be

components/crx_file/crx_creator.cc

@@ -81,7 +81,8 @@ CreatorResult SignArchiveAndCreateHeader(const base::FilePath& output_path,
   // through, run ZIP through.
   auto signer = crypto::SignatureCreator::Create(
       signing_key, crypto::SignatureCreator::HashAlgorithm::SHA256);
-  signer->Update(kSignatureContext, std::size(kSignatureContext));
+  signer->Update(reinterpret_cast<const uint8_t*>(kSignatureContext),
+                 std::size(kSignatureContext));
   signer->Update(signed_header_size_octets,
                  std::size(signed_header_size_octets));
   signer->Update(

components/crx_file/crx_file.h

@@ -11,7 +11,7 @@ namespace crx_file {
 constexpr char kCrxFileHeaderMagic[] = "Cr24";
 constexpr char kCrxDiffFileHeaderMagic[] = "CrOD";
 constexpr int kCrxFileHeaderMagicSize = 4;
-constexpr unsigned char kSignatureContext[] = u8"CRX3 SignedData";
+constexpr char kSignatureContext[] = "CRX3 SignedData";
 
 }  // namespace crx_file
 

components/crx_file/crx_verifier.cc

@@ -188,7 +188,7 @@ VerifierResult VerifyCrx3(
                          base::as_bytes(base::make_span(sig)),
                          base::as_bytes(base::make_span(key))))
         return VerifierResult::ERROR_SIGNATURE_INITIALIZATION_FAILED;
-      v->VerifyUpdate(kSignatureContext);
+      v->VerifyUpdate(base::as_bytes(base::make_span(kSignatureContext)));
       v->VerifyUpdate(header_size_octets);
       v->VerifyUpdate(base::as_bytes(base::make_span(signed_header_data_str)));
       verifiers.push_back(std::move(v));

components/feed/core/v2/public/types.h

@@ -106,10 +106,6 @@ struct NetworkResponse {
   std::string response_bytes;
   // HTTP status code if available, or net::Error otherwise.
   int status_code;
-
-  NetworkResponse() = default;
-  NetworkResponse(NetworkResponse&& other) = default;
-  NetworkResponse& operator=(NetworkResponse&& other) = default;
 };
 
 // For the snippets-internals page.

components/metrics/file_metrics_provider.cc

@@ -53,10 +53,8 @@ struct SourceOptions {
   bool is_read_only;
 };
 
-enum : int {
-  // Opening a file typically requires at least these flags.
-  STD_OPEN = base::File::FLAG_OPEN | base::File::FLAG_READ,
-};
+// Opening a file typically requires at least these flags.
+constexpr int STD_OPEN = base::File::FLAG_OPEN | base::File::FLAG_READ;
 
 constexpr SourceOptions kSourceOptions[] = {
     // SOURCE_HISTOGRAMS_ATOMIC_FILE

components/omnibox/browser/history_fuzzy_provider.cc

@@ -206,10 +206,6 @@ bool Node::FindCorrections(const std::u16string& text,
     // TODO(orinj): This should be optimized in final algorithm; stop copying.
     Correction correction;
 
-    Step(const Step&) = default;
-    Step(Step&&) = default;
-    Step& operator=(Step&&) = default;
-
     // std::priority_queue keeps the greatest element on top, so we want this
     // operator implementation to make bad steps less than good steps.
     // Prioritize minimum distance, with index and length to break ties.

components/omnibox/browser/omnibox_edit_model_unittest.cc

@@ -163,24 +163,24 @@ TEST_F(OmniboxEditModelTest, AdjustTextForCopy) {
 
       // Verifies that non-ASCII characters are %-escaped for valid copied URLs,
       // as long as the host has not been modified from the page URL.
-      {u8"https://ja.wikipedia.org/wiki/目次", 0, "", false,
-       u8"https://ja.wikipedia.org/wiki/目次",
+      {"https://ja.wikipedia.org/wiki/目次", 0, "", false,
+       "https://ja.wikipedia.org/wiki/目次",
        "https://ja.wikipedia.org/wiki/%E7%9B%AE%E6%AC%A1", true,
        "https://ja.wikipedia.org/wiki/%E7%9B%AE%E6%AC%A1"},
       // Test escaping when part of the path was not copied.
-      {u8"https://ja.wikipedia.org/wiki/目次", 0, "", false,
-       u8"https://ja.wikipedia.org/wiki/目",
+      {"https://ja.wikipedia.org/wiki/目次", 0, "", false,
+       "https://ja.wikipedia.org/wiki/目",
        "https://ja.wikipedia.org/wiki/%E7%9B%AE", true,
        "https://ja.wikipedia.org/wiki/%E7%9B%AE"},
       // Correctly handle escaping in the scheme-elided case as well.
-      {u8"https://ja.wikipedia.org/wiki/目次", 0, "", false,
-       u8"ja.wikipedia.org/wiki/目次",
+      {"https://ja.wikipedia.org/wiki/目次", 0, "", false,
+       "ja.wikipedia.org/wiki/目次",
        "https://ja.wikipedia.org/wiki/%E7%9B%AE%E6%AC%A1", true,
        "https://ja.wikipedia.org/wiki/%E7%9B%AE%E6%AC%A1",
-       u8"ja.wikipedia.org/wiki/目次"},
+       "ja.wikipedia.org/wiki/目次"},
       // Don't escape when host was modified.
-      {u8"https://ja.wikipedia.org/wiki/目次", 0, "", false,
-       u8"https://wikipedia.org/wiki/目次", u8"https://wikipedia.org/wiki/目次",
+      {"https://ja.wikipedia.org/wiki/目次", 0, "", false,
+       "https://wikipedia.org/wiki/目次", "https://wikipedia.org/wiki/目次",
        false, ""},
   };
 

components/omnibox/browser/titled_url_match_utils.cc

@@ -26,11 +26,12 @@ std::u16string ConcatAncestorsTitles(
     std::vector<base::StringPiece16> ancestors) {
   return ancestors.empty()
              ? std::u16string()
-             : std::accumulate(std::next(ancestors.rbegin()), ancestors.rend(),
-                               std::u16string(*ancestors.rbegin()),
-                               [](std::u16string& a, base::StringPiece16& b) {
-                                 return a + u"/" + std::u16string(b);
-                               });
+             : std::accumulate(
+                   std::next(ancestors.rbegin()), ancestors.rend(),
+                   std::u16string(*ancestors.rbegin()),
+                   [](const std::u16string& a, const base::StringPiece16& b) {
+                     return a + u"/" + std::u16string(b);
+                   });
 }
 
 }  // namespace

components/page_load_metrics/browser/page_load_metrics_observer.h

@@ -105,8 +105,6 @@ struct PageRenderData {
 
 // Information related to layout shift normalization for different strategies.
 struct NormalizedCLSData {
-  NormalizedCLSData() = default;
-
   // Maximum CLS of session windows. The gap between two consecutive shifts is
   // not bigger than 1000ms and the maximum window size is 5000ms.
   float session_windows_gap1000ms_max5000ms_max_cls = 0.0;

components/password_manager/core/browser/site_affiliation/asset_link_data_unittest.cc

@@ -15,7 +15,7 @@ using ::testing::ElementsAre;
 using ::testing::UnorderedElementsAre;
 
 TEST(AssetLinkData, NonJSON) {
-  constexpr char json[] = u8R"([trash])";
+  constexpr char json[] = R"([trash])";
   AssetLinkData data;
   EXPECT_FALSE(data.Parse(json));
   EXPECT_THAT(data.includes(), IsEmpty());
@@ -24,7 +24,7 @@ TEST(AssetLinkData, NonJSON) {
 
 TEST(AssetLinkData, NotList) {
   constexpr char json[] =
-      u8R"({
+      R"({
       "include": "https://example/.well-known/assetlinks.json"
   })";
   AssetLinkData data;
@@ -35,7 +35,7 @@ TEST(AssetLinkData, NotList) {
 
 TEST(AssetLinkData, IncludeWrongValue) {
   constexpr char json[] =
-      u8R"([{
+      R"([{
       "include": 24
   }])";
   AssetLinkData data;
@@ -46,7 +46,7 @@ TEST(AssetLinkData, IncludeWrongValue) {
 
 TEST(AssetLinkData, IncludeFile) {
   constexpr char json[] =
-      u8R"([{
+      R"([{
       "include": "https://example/.well-known/assetlinks.json"
   }])";
   AssetLinkData data;
@@ -58,7 +58,7 @@ TEST(AssetLinkData, IncludeFile) {
 
 TEST(AssetLinkData, IncludeHTTPFile) {
   constexpr char json[] =
-      u8R"([{
+      R"([{
       "include": "http://example/.well-known/assetlinks.json"
   }])";
   AssetLinkData data;
@@ -69,7 +69,7 @@ TEST(AssetLinkData, IncludeHTTPFile) {
 
 TEST(AssetLinkData, IncludeInvalidFile) {
   constexpr char json[] =
-      u8R"([{
+      R"([{
       "include": "www.example/assetlinks.json"
   }])";
   AssetLinkData data;
@@ -80,7 +80,7 @@ TEST(AssetLinkData, IncludeInvalidFile) {
 
 TEST(AssetLinkData, HandleURLsPermission) {
   constexpr char json[] =
-      u8R"([{
+      R"([{
   "relation": ["delegate_permission/common.handle_all_urls"],
   "target": {
     "namespace": "web",
@@ -102,7 +102,7 @@ TEST(AssetLinkData, HandleURLsPermission) {
 
 TEST(AssetLinkData, BrokenRelation) {
   constexpr char json[] =
-      u8R"([{
+      R"([{
   "relation": "delegate_permission/common.get_login_creds",
   "target": {
     "namespace": "web",
@@ -117,7 +117,7 @@ TEST(AssetLinkData, BrokenRelation) {
 
 TEST(AssetLinkData, GetLoginCredsPermission) {
   constexpr char json[] =
-      u8R"([{
+      R"([{
   "relation": ["delegate_permission/common.get_login_creds"],
   "target": {
     "namespace": "web",
@@ -154,7 +154,7 @@ TEST(AssetLinkData, GetLoginCredsPermission) {
 
 TEST(AssetLinkData, MultiplePermissions) {
   constexpr char json[] =
-      u8R"([{
+      R"([{
   "relation": ["something","delegate_permission/common.get_login_creds"],
   "target": {
     "namespace": "web",
@@ -191,7 +191,7 @@ TEST(AssetLinkData, MultiplePermissions) {
 
 TEST(AssetLinkData, MixedStatements) {
   constexpr char json[] =
-      u8R"([{
+      R"([{
   "relation": ["delegate_permission/common.get_login_creds"],
   "target": {
     "namespace": "web",

components/prefs/pref_registry.h

@@ -37,19 +37,19 @@ class COMPONENTS_PREFS_EXPORT PrefRegistry
   // behave or be stored. This will be passed in a bitmask when the pref is
   // registered. Subclasses of PrefRegistry can specify their own flags. Care
   // must be taken to ensure none of these overlap with the flags below.
-  enum PrefRegistrationFlags : uint32_t {
-    // No flags are specified.
-    NO_REGISTRATION_FLAGS = 0,
+  using PrefRegistrationFlags = uint32_t;
 
-    // The first 8 bits are reserved for subclasses of PrefRegistry to use.
+  // No flags are specified.
+  static constexpr PrefRegistrationFlags NO_REGISTRATION_FLAGS = 0;
 
-    // This marks the pref as "lossy". There is no strict time guarantee on when
-    // a lossy pref will be persisted to permanent storage when it is modified.
-    LOSSY_PREF = 1 << 8,
+  // The first 8 bits are reserved for subclasses of PrefRegistry to use.
 
-    // Registering a pref as public allows other services to access it.
-    PUBLIC = 1 << 9,
-  };
+  // This marks the pref as "lossy". There is no strict time guarantee on when
+  // a lossy pref will be persisted to permanent storage when it is modified.
+  static constexpr PrefRegistrationFlags LOSSY_PREF = 1 << 8;
+
+  // Registering a pref as public allows other services to access it.
+  static constexpr PrefRegistrationFlags PUBLIC = 1 << 9;
 
   typedef PrefValueMap::const_iterator const_iterator;
   typedef std::unordered_map<std::string, uint32_t> PrefRegistrationFlagsMap;

components/segmentation_platform/internal/database/ukm_metrics_table.h

@@ -31,9 +31,6 @@ class UkmMetricsTable {
 
   // Represents a row in the metrics table.
   struct MetricsRow {
-    MetricsRow() = default;
-    ~MetricsRow() = default;
-
     // Timestamp of the event, all the metrics in the event will have the same
     // timestamp. The timestamp is approximate and generated by the database
     // when getting notifications about UKM. Timestamps are required since its

components/services/storage/indexed_db/locks/disjoint_range_lock_manager.cc

@@ -133,7 +133,7 @@ bool DisjointRangeLockManager::AcquireLock(
   if (it == level_locks.end()) {
     it = level_locks
              .emplace(std::piecewise_construct,
-                      std::forward_as_tuple(std::move(request.range)),
+                      std::forward_as_tuple(request.range),
                       std::forward_as_tuple())
              .first;
   }

components/services/storage/indexed_db/locks/leveled_lock_range.h

@@ -15,8 +15,6 @@ namespace content {
 // The range is [begin, end). Bytewise comparison is used to determine
 // overlapping ranges.
 struct COMPONENT_EXPORT(LOCK_MANAGER) LeveledLockRange {
-  LeveledLockRange() = default;
-  ~LeveledLockRange() = default;
   std::string begin;
   std::string end;
 

components/signin/core/browser/signin_status_metrics_provider_helpers.h

@@ -31,8 +31,6 @@ enum class SigninOrSyncStatus {
 // Provides information relating to the status of profiles in the embedder:
 // how many are open, how many are signed in, and how many are syncing.
 struct ProfilesStatus {
-  ProfilesStatus() = default;
-
   size_t num_opened_profiles = 0;
   size_t num_signed_in_profiles = 0;
   size_t num_syncing_profiles = 0;

components/url_pattern_index/ngram_extractor.h

@@ -37,8 +37,14 @@ template <size_t N,
 class NGramExtractor {
  public:
   // An STL compatible input iterator over N-grams contained in a string.
-  class Iterator : public std::iterator<std::input_iterator_tag, NGramType> {
+  class Iterator {
    public:
+    using iterator_category = std::input_iterator_tag;
+    using value_type = NGramType;
+    using difference_type = std::ptrdiff_t;
+    using pointer = NGramType*;
+    using reference = NGramType&;
+
     // Creates an iterator, which points to the leftmost valid N-gram within the
     // |extractor|'s string, starting from |head|.
     Iterator(const NGramExtractor& extractor,

components/url_pattern_index/string_splitter.h

@@ -23,9 +23,14 @@ namespace url_pattern_index {
 template <typename IsSeparator>
 class StringSplitter {
  public:
-  class Iterator
-      : public std::iterator<std::input_iterator_tag, base::StringPiece> {
+  class Iterator {
    public:
+    using iterator_category = std::input_iterator_tag;
+    using value_type = base::StringPiece;
+    using difference_type = std::ptrdiff_t;
+    using pointer = base::StringPiece*;
+    using reference = base::StringPiece&;
+
     // Creates an iterator, which points to the leftmost token within the
     // |splitter|'s |text|, starting from |head|.
     Iterator(const StringSplitter& splitter,

components/viz/service/display/dc_layer_overlay.h

@@ -169,10 +169,10 @@ class VIZ_SERVICE_EXPORT DCLayerOverlayProcessor
   struct OverlayRect {
     gfx::Rect rect;
     bool is_overlay;  // If false, it's an underlay.
-    bool operator==(const OverlayRect& b) {
+    bool operator==(const OverlayRect& b) const {
       return rect == b.rect && is_overlay == b.is_overlay;
     }
-    bool operator!=(const OverlayRect& b) { return !(*this == b); }
+    bool operator!=(const OverlayRect& b) const { return !(*this == b); }
   };
   std::vector<OverlayRect> previous_frame_overlay_rects_;
   std::vector<OverlayRect> current_frame_overlay_rects_;

components/web_package/web_bundle_builder.cc

@@ -155,8 +155,7 @@ cbor::Value WebBundleBuilder::CreateEncodedSigned(
 
 std::vector<uint8_t> WebBundleBuilder::CreateTopLevel() {
   cbor::Value::ArrayValue toplevel_array;
-  toplevel_array.emplace_back(
-      CreateByteString(u8"\U0001F310\U0001F4E6"));  // "🌐📦"
+  toplevel_array.emplace_back(CreateByteString("🌐📦"));
   toplevel_array.emplace_back(CreateByteString(base::StringPiece("b2\0\0", 4)));
   toplevel_array.emplace_back(Encode(cbor::Value(section_lengths_)));
   toplevel_array.emplace_back(sections_);