Reapply [Tooling] Make clang-tool find libc++ dir on mac when running on a file without compilation database.

This reverts commit r351282, and re-lands r351222 and r351229 with the
use-after-free fixed.

3 files changed, 49 insertions, 38 deletions

diff --git a/clang/lib/Tooling/CompilationDatabase.cpp b/clang/lib/Tooling/CompilationDatabase.cpp
index 246d3c0a78f..cce8e1f1df2 100644
--- a/clang/lib/Tooling/CompilationDatabase.cpp
+++ b/clang/lib/Tooling/CompilationDatabase.cpp
@@ -227,6 +227,16 @@ struct FilterUnusedFlags {
   }
 };
 
+std::string GetClangToolCommand() {
+  static int Dummy;
+  std::string ClangExecutable =
+      llvm::sys::fs::getMainExecutable("clang", (void *)&Dummy);
+  SmallString<128> ClangToolPath;
+  ClangToolPath = llvm::sys::path::parent_path(ClangExecutable);
+  llvm::sys::path::append(ClangToolPath, "clang-tool");
+  return ClangToolPath.str();
+}
+
 } // namespace
 
 /// Strips any positional args and possible argv[0] from a command-line
@@ -266,9 +276,10 @@ static bool stripPositionalArgs(std::vector<const char *> Args,
       Diagnostics));
   NewDriver->setCheckInputsExist(false);
 
-  // This becomes the new argv[0]. The value is actually not important as it
-  // isn't used for invoking Tools.
-  Args.insert(Args.begin(), "clang-tool");
+  // This becomes the new argv[0]. The value is used to detect libc++ include
+  // dirs on Mac, it isn't used for other platforms.
+  std::string Argv0 = GetClangToolCommand();
+  Args.insert(Args.begin(), Argv0.c_str());
 
   // By adding -c, we force the driver to treat compilation as the last phase.
   // It will then issue warnings via Diagnostics about un-used options that
@@ -366,7 +377,7 @@ FixedCompilationDatabase::loadFromFile(StringRef Path, std::string &ErrorMsg) {
 
 FixedCompilationDatabase::
 FixedCompilationDatabase(Twine Directory, ArrayRef<std::string> CommandLine) {
-  std::vector<std::string> ToolCommandLine(1, "clang-tool");
+  std::vector<std::string> ToolCommandLine(1, GetClangToolCommand());
   ToolCommandLine.insert(ToolCommandLine.end(),
                          CommandLine.begin(), CommandLine.end());
   CompileCommands.emplace_back(Directory, StringRef(),
diff --git a/clang/test/Tooling/clang-check-mac-libcxx-fixed-compilation-db.cpp b/clang/test/Tooling/clang-check-mac-libcxx-fixed-compilation-db.cpp
new file mode 100644
index 00000000000..035155c96c9
--- /dev/null
+++ b/clang/test/Tooling/clang-check-mac-libcxx-fixed-compilation-db.cpp
@@ -0,0 +1,16 @@
+// Clang on MacOS can find libc++ living beside the installed compiler.
+// This test makes sure our libTooling-based tools emulate this properly with
+// fixed compilation database.
+//
+// RUN: rm -rf %t
+// RUN: mkdir %t
+//
+// Install the mock libc++ (simulates the libc++ directory structure).
+// RUN: cp -r %S/Inputs/mock-libcxx %t/
+//
+// RUN: cp $(which clang-check) %t/mock-libcxx/bin/
+// RUN: cp "%s" "%t/test.cpp"
+// RUN: %t/mock-libcxx/bin/clang-check -p "%t" "%t/test.cpp" -- -stdlib=libc++
+
+#include <mock_vector>
+vector v;
diff --git a/clang/unittests/Tooling/CompilationDatabaseTest.cpp b/clang/unittests/Tooling/CompilationDatabaseTest.cpp
index 125ba4896ef..949d6a3b739 100644
--- a/clang/unittests/Tooling/CompilationDatabaseTest.cpp
+++ b/clang/unittests/Tooling/CompilationDatabaseTest.cpp
@@ -14,11 +14,15 @@
 #include "clang/Tooling/JSONCompilationDatabase.h"
 #include "clang/Tooling/Tooling.h"
 #include "llvm/Support/Path.h"
+#include "gmock/gmock.h"
 #include "gtest/gtest.h"
 
 namespace clang {
 namespace tooling {
 
+using testing::ElementsAre;
+using testing::EndsWith;
+
 static void expectFailure(StringRef JSONDatabase, StringRef Explanation) {
   std::string ErrorMessage;
   EXPECT_EQ(nullptr,
@@ -467,21 +471,15 @@ TEST(unescapeJsonCommandLine, ParsesSingleQuotedString) {
 }
 
 TEST(FixedCompilationDatabase, ReturnsFixedCommandLine) {
-  std::vector<std::string> CommandLine;
-  CommandLine.push_back("one");
-  CommandLine.push_back("two");
-  FixedCompilationDatabase Database(".", CommandLine);
+  FixedCompilationDatabase Database(".", /*CommandLine*/ {"one", "two"});
   StringRef FileName("source");
   std::vector<CompileCommand> Result =
     Database.getCompileCommands(FileName);
   ASSERT_EQ(1ul, Result.size());
-  std::vector<std::string> ExpectedCommandLine(1, "clang-tool");
-  ExpectedCommandLine.insert(ExpectedCommandLine.end(),
-                             CommandLine.begin(), CommandLine.end());
-  ExpectedCommandLine.push_back("source");
   EXPECT_EQ(".", Result[0].Directory);
   EXPECT_EQ(FileName, Result[0].Filename);
-  EXPECT_EQ(ExpectedCommandLine, Result[0].CommandLine);
+  EXPECT_THAT(Result[0].CommandLine,
+              ElementsAre(EndsWith("clang-tool"), "one", "two", "source"));
 }
 
 TEST(FixedCompilationDatabase, GetAllFiles) {
@@ -537,12 +535,8 @@ TEST(ParseFixedCompilationDatabase, ReturnsArgumentsAfterDoubleDash) {
     Database->getCompileCommands("source");
   ASSERT_EQ(1ul, Result.size());
   ASSERT_EQ(".", Result[0].Directory);
-  std::vector<std::string> CommandLine;
-  CommandLine.push_back("clang-tool");
-  CommandLine.push_back("-DDEF3");
-  CommandLine.push_back("-DDEF4");
-  CommandLine.push_back("source");
-  ASSERT_EQ(CommandLine, Result[0].CommandLine);
+  ASSERT_THAT(Result[0].CommandLine, ElementsAre(EndsWith("clang-tool"),
+                                                 "-DDEF3", "-DDEF4", "source"));
   EXPECT_EQ(2, Argc);
 }
 
@@ -558,10 +552,8 @@ TEST(ParseFixedCompilationDatabase, ReturnsEmptyCommandLine) {
     Database->getCompileCommands("source");
   ASSERT_EQ(1ul, Result.size());
   ASSERT_EQ(".", Result[0].Directory);
-  std::vector<std::string> CommandLine;
-  CommandLine.push_back("clang-tool");
-  CommandLine.push_back("source");
-  ASSERT_EQ(CommandLine, Result[0].CommandLine);
+  ASSERT_THAT(Result[0].CommandLine,
+              ElementsAre(EndsWith("clang-tool"), "source"));
   EXPECT_EQ(2, Argc);
 }
 
@@ -577,12 +569,8 @@ TEST(ParseFixedCompilationDatabase, HandlesPositionalArgs) {
     Database->getCompileCommands("source");
   ASSERT_EQ(1ul, Result.size());
   ASSERT_EQ(".", Result[0].Directory);
-  std::vector<std::string> Expected;
-  Expected.push_back("clang-tool");
-  Expected.push_back("-c");
-  Expected.push_back("-DDEF3");
-  Expected.push_back("source");
-  ASSERT_EQ(Expected, Result[0].CommandLine);
+  ASSERT_THAT(Result[0].CommandLine,
+              ElementsAre(EndsWith("clang-tool"), "-c", "-DDEF3", "source"));
   EXPECT_EQ(2, Argc);
 }
 
@@ -599,12 +587,9 @@ TEST(ParseFixedCompilationDatabase, HandlesPositionalArgsSyntaxOnly) {
   std::vector<CompileCommand> Result = Database->getCompileCommands("source");
   ASSERT_EQ(1ul, Result.size());
   ASSERT_EQ(".", Result[0].Directory);
-  std::vector<std::string> Expected;
-  Expected.push_back("clang-tool");
-  Expected.push_back("-fsyntax-only");
-  Expected.push_back("-DDEF3");
-  Expected.push_back("source");
-  ASSERT_EQ(Expected, Result[0].CommandLine);
+  ASSERT_THAT(
+      Result[0].CommandLine,
+      ElementsAre(EndsWith("clang-tool"), "-fsyntax-only", "-DDEF3", "source"));
 }
 
 TEST(ParseFixedCompilationDatabase, HandlesArgv0) {
@@ -620,9 +605,8 @@ TEST(ParseFixedCompilationDatabase, HandlesArgv0) {
   ASSERT_EQ(1ul, Result.size());
   ASSERT_EQ(".", Result[0].Directory);
   std::vector<std::string> Expected;
-  Expected.push_back("clang-tool");
-  Expected.push_back("source");
-  ASSERT_EQ(Expected, Result[0].CommandLine);
+  ASSERT_THAT(Result[0].CommandLine,
+              ElementsAre(EndsWith("clang-tool"), "source"));
   EXPECT_EQ(2, Argc);
 }