[clang] Use StringRef::operator== instead of StringRef::equals (NFC) (#91844)

I'm planning to remove StringRef::equals in favor of
StringRef::operator==.

- StringRef::operator==/!= outnumber StringRef::equals by a factor of
  24 under clang/ in terms of their usage.

- The elimination of StringRef::equals brings StringRef closer to
  std::string_view, which has operator== but not equals.

- S == "foo" is more readable than S.equals("foo"), especially for
  !Long.Expression.equals("str") vs Long.Expression != "str".

2 files changed, 3 insertions, 3 deletions

diff --git a/clang/tools/diagtool/ShowEnabledWarnings.cpp b/clang/tools/diagtool/ShowEnabledWarnings.cpp
index 285efe6..66a295d 100644
--- a/clang/tools/diagtool/ShowEnabledWarnings.cpp
+++ b/clang/tools/diagtool/ShowEnabledWarnings.cpp
@@ -90,11 +90,11 @@ int ShowEnabledWarnings::run(unsigned int argc, char **argv, raw_ostream &Out) {
   bool ShouldShowLevels = true;
   if (argc > 0) {
     StringRef FirstArg(*argv);
-    if (FirstArg.equals("--no-levels")) {
+    if (FirstArg == "--no-levels") {
       ShouldShowLevels = false;
       --argc;
       ++argv;
-    } else if (FirstArg.equals("--levels")) {
+    } else if (FirstArg == "--levels") {
       ShouldShowLevels = true;
       --argc;
       ++argv;
diff --git a/clang/tools/diagtool/TreeView.cpp b/clang/tools/diagtool/TreeView.cpp
index 00d1097..8d1ce14 100644
--- a/clang/tools/diagtool/TreeView.cpp
+++ b/clang/tools/diagtool/TreeView.cpp
@@ -144,7 +144,7 @@ int TreeView::run(unsigned int argc, char **argv, llvm::raw_ostream &out) {
   bool Internal = false;
   if (argc > 0) {
     StringRef FirstArg(*argv);
-    if (FirstArg.equals("--internal")) {
+    if (FirstArg == "--internal") {
       Internal = true;
       --argc;
       ++argv;