[JSONCompilationDatabase] Strip distcc/ccache/gomacc wrappers from parsed commands.

Summary:
It's common to use compiler wrappers by setting CC="gomacc clang++".
This results in both args appearing in compile_commands.json, and clang's driver
can't handle this.

This patch attempts to recognize this pattern (by looking for well-known
wrappers) and dropping argv0 in this case.

It conservatively ignores other cases for now:
 - wrappers with unknown names
 - wrappers that accept -flags
 - wrappers where the compiler to use is implied (usually cc or gcc)

This is done at the JSONCompilationDatabase level rather than somewhere more
fundamental, as (hopefully) this isn't a general conceptual problem, but a messy
aspect of the nature of the ecosystem around compile_commands.json.
i.e. compilation databases more tightly tied to the build system should not have
this problem.

Reviewers: phosek, klimek

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D64297

llvm-svn: 365887

1 files changed, 24 insertions, 0 deletions

diff --git a/clang/unittests/Tooling/CompilationDatabaseTest.cpp b/clang/unittests/Tooling/CompilationDatabaseTest.cpp
index da7ae09..6794029 100644
--- a/clang/unittests/Tooling/CompilationDatabaseTest.cpp
+++ b/clang/unittests/Tooling/CompilationDatabaseTest.cpp
@@ -370,6 +370,30 @@ TEST(findCompileArgsInJsonDatabase, FindsEntry) {
   EXPECT_EQ("command4", FoundCommand.CommandLine[0]) << ErrorMessage;
 }
 
+TEST(findCompileArgsInJsonDatabase, ParsesCompilerWrappers) {
+  std::vector<std::pair<std::string, std::string>> Cases = {
+      {"distcc gcc foo.c", "gcc foo.c"},
+      {"gomacc clang++ foo.c", "clang++ foo.c"},
+      {"ccache gcc foo.c", "gcc foo.c"},
+      {"ccache.exe gcc foo.c", "gcc foo.c"},
+      {"ccache g++.exe foo.c", "g++.exe foo.c"},
+      {"ccache distcc gcc foo.c", "gcc foo.c"},
+
+      {"distcc foo.c", "distcc foo.c"},
+      {"distcc -I/foo/bar foo.c", "distcc -I/foo/bar foo.c"},
+  };
+  std::string ErrorMessage;
+
+  for (const auto &Case : Cases) {
+    std::string DB = R"([{"directory":".", "file":"/foo.c", "command":")" +
+                     Case.first + "\"}]";
+    CompileCommand FoundCommand =
+        findCompileArgsInJsonDatabase("/foo.c", DB, ErrorMessage);
+    EXPECT_EQ(Case.second, llvm::join(FoundCommand.CommandLine, " "))
+        << Case.first;
+  }
+}
+
 static std::vector<std::string> unescapeJsonCommandLine(StringRef Command) {
   std::string JsonDatabase =
     ("[{\"directory\":\"//net/root\", \"file\":\"test\", \"command\": \"" +