[clang] Use StringRef::consume_front (NFC)

Author: kazutakahirata

clang/lib/CodeGen/CodeGenAction.cpp

@@ -1139,8 +1139,7 @@ CodeGenAction::loadModule(MemoryBufferRef MBRef) {
 
   // Strip off a leading diagnostic code if there is one.
   StringRef Msg = Err.getMessage();
-  if (Msg.starts_with("error: "))
-    Msg = Msg.substr(7);
+  Msg.consume_front("error: ");
 
   unsigned DiagID =
       CI.getDiagnostics().getCustomDiagID(DiagnosticsEngine::Error, "%0");

clang/lib/Driver/ToolChains/CommonArgs.cpp

@@ -2388,8 +2388,7 @@ static void GetSDLFromOffloadArchive(
       FoundAOB = true;
     }
   } else {
-    if (Lib.starts_with("-l"))
-      Lib = Lib.drop_front(2);
+    Lib.consume_front("-l");
     for (auto LPath : LibraryPaths) {
       ArchiveOfBundles.clear();
       auto LibFile = (Lib.starts_with(":") ? Lib.drop_front()

clang/lib/Frontend/DependencyGraph.cpp

@@ -110,8 +110,7 @@ void DependencyGraphCallback::OutputGraphFile() {
     writeNodeReference(OS, AllFiles[I]);
     OS << " [ shape=\"box\", label=\"";
     StringRef FileName = AllFiles[I].getName();
-    if (FileName.starts_with(SysRoot))
-      FileName = FileName.substr(SysRoot.size());
+    FileName.consume_front(SysRoot);
 
     OS << DOT::EscapeString(std::string(FileName)) << "\"];\n";
   }

clang/lib/Frontend/VerifyDiagnosticConsumer.cpp

@@ -1144,8 +1144,7 @@ std::unique_ptr<Directive> Directive::create(bool RegexKind,
   std::string RegexStr;
   StringRef S = Text;
   while (!S.empty()) {
-    if (S.starts_with("{{")) {
-      S = S.drop_front(2);
+    if (S.consume_front("{{")) {
       size_t RegexMatchLength = S.find("}}");
       assert(RegexMatchLength != StringRef::npos);
       // Append the regex, enclosed in parentheses.

clang/lib/Sema/SemaChecking.cpp

@@ -1219,8 +1219,8 @@ void Sema::checkFortifiedBuiltinMemoryFunction(FunctionDecl *FD,
     if (IsChkVariant) {
       FunctionName = FunctionName.drop_front(std::strlen("__builtin___"));
       FunctionName = FunctionName.drop_back(std::strlen("_chk"));
-    } else if (FunctionName.starts_with("__builtin_")) {
-      FunctionName = FunctionName.drop_front(std::strlen("__builtin_"));
+    } else {
+      FunctionName.consume_front("__builtin_");
     }
     return FunctionName;
   };

clang/lib/Sema/SemaDeclAttr.cpp

@@ -5825,8 +5825,7 @@ struct IntrinToName {
 static bool ArmBuiltinAliasValid(unsigned BuiltinID, StringRef AliasName,
                                  ArrayRef<IntrinToName> Map,
                                  const char *IntrinNames) {
-  if (AliasName.starts_with("__arm_"))
-    AliasName = AliasName.substr(6);
+  AliasName.consume_front("__arm_");
   const IntrinToName *It =
       llvm::lower_bound(Map, BuiltinID, [](const IntrinToName &L, unsigned Id) {
         return L.Id < Id;

clang/lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp

@@ -140,8 +140,7 @@ void WalkAST::VisitCallExpr(CallExpr *CE) {
   if (!II)   // if no identifier, not a simple C function
     return;
   StringRef Name = II->getName();
-  if (Name.starts_with("__builtin_"))
-    Name = Name.substr(10);
+  Name.consume_front("__builtin_");
 
   // Set the evaluation function by switching on the callee name.
   FnCheck evalFunction =
@@ -763,8 +762,7 @@ void WalkAST::checkDeprecatedOrUnsafeBufferHandling(const CallExpr *CE,
   enum { DEPR_ONLY = -1, UNKNOWN_CALL = -2 };
 
   StringRef Name = FD->getIdentifier()->getName();
-  if (Name.starts_with("__builtin_"))
-    Name = Name.substr(10);
+  Name.consume_front("__builtin_");
 
   int ArgIndex =
       llvm::StringSwitch<int>(Name)

clang/lib/Tooling/Refactoring/Lookup.cpp

@@ -98,8 +98,8 @@ static StringRef getBestNamespaceSubstr(const DeclContext *DeclA,
     // from NewName if it has an identical prefix.
     std::string NS =
         "::" + cast<NamespaceDecl>(DeclA)->getQualifiedNameAsString() + "::";
-    if (NewName.starts_with(NS))
-      return NewName.substr(NS.size());
+    if (NewName.consume_front(NS))
+      return NewName;
 
     // No match yet. Strip of a namespace from the end of the chain and try
     // again. This allows to get optimal qualifications even if the old and new

clang/lib/Tooling/Tooling.cpp

@@ -255,9 +255,7 @@ llvm::Expected<std::string> getAbsolutePath(llvm::vfs::FileSystem &FS,
                                             StringRef File) {
   StringRef RelativePath(File);
   // FIXME: Should '.\\' be accepted on Win32?
-  if (RelativePath.starts_with("./")) {
-    RelativePath = RelativePath.substr(strlen("./"));
-  }
+  RelativePath.consume_front("./");
 
   SmallString<1024> AbsolutePath = RelativePath;
   if (auto EC = FS.makeAbsolute(AbsolutePath))