[clang][Tooling] Filter flags that generate output in SyntaxOnlyAdjuster

Summary:
Flags that generate output could result in failures when creating
syntax only actions. This patch introduces initial logic for filtering out
those. The first such flag is "save-temps", which saves intermediate
files(bitcode, assembly, etc.) into a specified directory.

Fixes https://github.com/clangd/clangd/issues/191

Reviewers: hokein

Subscribers: ilya-biryukov, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D70173

1 files changed, 14 insertions, 2 deletions

diff --git a/clang/lib/Tooling/ArgumentsAdjusters.cpp b/clang/lib/Tooling/ArgumentsAdjusters.cpp
index f56d08c47b9..a609e4ed246 100644
--- a/clang/lib/Tooling/ArgumentsAdjusters.cpp
+++ b/clang/lib/Tooling/ArgumentsAdjusters.cpp
@@ -13,20 +13,32 @@
 
 #include "clang/Tooling/ArgumentsAdjusters.h"
 #include "clang/Basic/LLVM.h"
+#include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringRef.h"
 #include <cstddef>
+#include <vector>
 
 namespace clang {
 namespace tooling {
 
-/// Add -fsyntax-only option to the command line arguments.
+/// Add -fsyntax-only option and drop options that triggers output generation.
 ArgumentsAdjuster getClangSyntaxOnlyAdjuster() {
   return [](const CommandLineArguments &Args, StringRef /*unused*/) {
     CommandLineArguments AdjustedArgs;
     bool HasSyntaxOnly = false;
+    const std::vector<llvm::StringRef> OutputCommands = {
+        // FIXME: Add other options that generate output.
+        "-save-temps",
+        "--save-temps",
+    };
     for (size_t i = 0, e = Args.size(); i < e; ++i) {
       StringRef Arg = Args[i];
-      // FIXME: Remove options that generate output.
+      // Skip output commands.
+      if (llvm::any_of(OutputCommands, [&Arg](llvm::StringRef OutputCommand) {
+            return Arg.startswith(OutputCommand);
+          }))
+        continue;
+
       if (!Arg.startswith("-fcolor-diagnostics") &&
           !Arg.startswith("-fdiagnostics-color"))
         AdjustedArgs.push_back(Args[i]);