Fix issues reported by -Wrange-loop-analysis when building with latest Clang (trunk). NFC.

Fixes warning: loop variable 'E' of type 'const llvm::StringRef' creates a copy from type 'const llvm::StringRef' [-Wrange-loop-analysis]

clang-tools-extra/clangd/unittests/ParsedASTTests.cpp

@@ -56,7 +56,7 @@ MATCHER_P(WithTemplateArgs, ArgName, "") {
       LangOptions LO;
       PrintingPolicy Policy(LO);
       Policy.adjustForCPlusPlus();
-      for (const auto Arg : Args->asArray()) {
+      for (const auto &Arg : Args->asArray()) {
         if (SpecializationArgs.size() > 0)
           SpecializationArgs += ",";
         SpecializationArgs += Arg.getAsType().getAsString(Policy);

clang-tools-extra/clangd/unittests/RenameTests.cpp

@@ -404,7 +404,7 @@ TEST(RenameTest, WithinFileRename) {
         template <> struct Bar<[[Foo]]> {};
       )cpp",
   };
-  for (const auto T : Tests) {
+  for (llvm::StringRef T : Tests) {
     Annotations Code(T);
     auto TU = TestTU::withCode(Code.code());
     TU.ExtraArgs.push_back("-fno-delayed-template-parsing");

llvm/lib/Support/Windows/Program.inc

@@ -197,7 +197,7 @@ static bool Execute(ProcessInfo &PI, StringRef Program,
     // An environment block consists of a null-terminated block of
     // null-terminated strings. Convert the array of environment variables to
     // an environment block by concatenating them.
-    for (const auto E : *Env) {
+    for (StringRef E : *Env) {
       SmallVector<wchar_t, MAX_PATH> EnvString;
       if (std::error_code ec = windows::UTF8ToUTF16(E, EnvString)) {
         SetLastError(ec.value());