Fix clang Wrange-loop-analysis in BuildTree.cpp

[jthemphill]

Summary

Building on Mac OS with clang 12:

jhemphill@jhemphill-mbp build % clang --version
Apple clang version 12.0.0 (clang-1200.0.26.2)
Target: x86_64-apple-darwin19.6.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

yields one warning:

/Users/jhemphill/oss/llvm-project/clang/lib/Tooling/Syntax/BuildTree.cpp:1126:22: warning: loop variable 'Arg' is always a copy because the range of type 'llvm::iterator_range<clang::Stmt::CastIterator<clang::Expr, clang::Expr *, clang::Stmt *> >' does not return a reference [-Wrange-loop-analysis]
    for (const auto &Arg : Args) {
                     ^
/Users/jhemphill/oss/llvm-project/clang/lib/Tooling/Syntax/BuildTree.cpp:1126:10: note: use non-reference type 'clang::Expr *'
    for (const auto &Arg : Args) {

It appears that Arg is an Expr*, passed by value rather than by const reference.

[jthemphill]

Will someone come by and land this?

[gribozavr2]

Sorry, I didn't realize you don't have commit access. Pushed this patch to git, thanks for the contribution!

clang/lib/Tooling/Syntax/BuildTree.cpp

bool WalkUpFromBinaryOperator(BinaryOperator *S) {
     return true;
   }
 
   /// Builds `CallArguments` syntax node from arguments that appear in source
   /// code, i.e. not default arguments.
   syntax::CallArguments *
   buildCallArguments(CallExpr::arg_range ArgsAndDefaultArgs) {
     auto Args = dropDefaultArgs(ArgsAndDefaultArgs);
-    for (const auto &Arg : Args) {
+    for (auto *Arg : Args) {
       Builder.markExprChild(Arg, syntax::NodeRole::ListElement);
       const auto *DelimiterToken =
           std::next(Builder.findToken(Arg->getEndLoc()));
       if (DelimiterToken->kind() == clang::tok::TokenKind::comma)
         Builder.markChildToken(DelimiterToken, syntax::NodeRole::ListDelimiter);
     }
 
     auto *Arguments = new (allocator()) syntax::CallArguments;