1 files changed, 16 insertions, 12 deletions
diff --git a/lib/Tooling/InterpolatingCompilationDatabase.cpp b/lib/Tooling/InterpolatingCompilationDatabase.cpp
index 4d0d84f660a2..53c8dd448fd9 100644
--- a/lib/Tooling/InterpolatingCompilationDatabase.cpp
+++ b/lib/Tooling/InterpolatingCompilationDatabase.cpp
@@ -1,9 +1,8 @@
 //===- InterpolatingCompilationDatabase.cpp ---------------------*- C++ -*-===//
 //
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
@@ -151,7 +150,8 @@ struct TransferableCommand {
     // spelling of each argument; re-rendering is lossy for aliased flags.
     // E.g. in CL mode, /W4 maps to -Wall.
     auto OptTable = clang::driver::createDriverOptTable();
-    Cmd.CommandLine.emplace_back(OldArgs.front());
+    if (!OldArgs.empty())
+      Cmd.CommandLine.emplace_back(OldArgs.front());
     for (unsigned Pos = 1; Pos < OldArgs.size();) {
       using namespace driver::options;
 
@@ -206,10 +206,13 @@ struct TransferableCommand {
     bool TypeCertain;
     auto TargetType = guessType(Filename, &TypeCertain);
     // If the filename doesn't determine the language (.h), transfer with -x.
-    if (TargetType != types::TY_INVALID && !TypeCertain && Type) {
-      TargetType = types::onlyPrecompileType(TargetType) // header?
-                       ? types::lookupHeaderTypeForSourceType(*Type)
-                       : *Type;
+    if ((!TargetType || !TypeCertain) && Type) {
+      // Use *Type, or its header variant if the file is a header.
+      // Treat no/invalid extension as header (e.g. C++ standard library).
+      TargetType =
+          (!TargetType || types::onlyPrecompileType(TargetType)) // header?
+              ? types::lookupHeaderTypeForSourceType(*Type)
+              : *Type;
       if (ClangCLMode) {
         const StringRef Flag = toCLFlag(TargetType);
         if (!Flag.empty())
@@ -227,6 +230,7 @@ struct TransferableCommand {
           LangStandard::getLangStandardForKind(Std).getName()).str());
     }
     Result.CommandLine.push_back(Filename);
+    Result.Heuristic = "inferred from " + Cmd.Filename;
     return Result;
   }
 
@@ -240,7 +244,8 @@ private:
     }
 
     // Otherwise just check the clang executable file name.
-    return llvm::sys::path::stem(CmdLine.front()).endswith_lower("cl");
+    return !CmdLine.empty() &&
+           llvm::sys::path::stem(CmdLine.front()).endswith_lower("cl");
   }
 
   // Map the language from the --std flag to that of the -x flag.
@@ -473,8 +478,7 @@ private:
                                  ArrayRef<SubstringAndIndex> Idx) const {
     assert(!Idx.empty());
     // Longest substring match will be adjacent to a direct lookup.
-    auto It =
-        std::lower_bound(Idx.begin(), Idx.end(), SubstringAndIndex{Key, 0});
+    auto It = llvm::lower_bound(Idx, SubstringAndIndex{Key, 0});
     if (It == Idx.begin())
       return *It;
     if (It == Idx.end())