[clang-tidy] Fail gracefully upon empty database fields

Fix bz#42281

Differential Revision: https://reviews.llvm.org/D63613

llvm-svn: 363975

1 files changed, 4 insertions, 2 deletions

diff --git a/clang/lib/Tooling/InterpolatingCompilationDatabase.cpp b/clang/lib/Tooling/InterpolatingCompilationDatabase.cpp
index 8b1030f3607..a467d1318e2 100644
--- a/clang/lib/Tooling/InterpolatingCompilationDatabase.cpp
+++ b/clang/lib/Tooling/InterpolatingCompilationDatabase.cpp
@@ -150,7 +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;
 
@@ -243,7 +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.