[clang] 966fac1 - [clang][Tooling] Fix potential UB in ExpandResponseFilesCompilationDatabase

[Sam McCall via cfe-commits]

Author: Sam McCall
Date: 2019-12-09T12:24:23+01:00
New Revision: 966fac1941ea99e076a7654d229b27e1e6e4ad17

URL: https://github.com/llvm/llvm-project/commit/966fac1941ea99e076a7654d229b27e1e6e4ad17
DIFF: https://github.com/llvm/llvm-project/commit/966fac1941ea99e076a7654d229b27e1e6e4ad17.diff

LOG: [clang][Tooling] Fix potential UB in ExpandResponseFilesCompilationDatabase

Summary:
`vector::assign` will cause UB at here.

fixes: https://github.com/clangd/clangd/issues/223

Reviewers: kadircet, sammccall, hokein

Reviewed By: sammccall

Subscribers: merge_guards_bot, ilya-biryukov, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D71172

Added: 
    

Modified: 
    clang/lib/Tooling/ExpandResponseFilesCompilationDatabase.cpp

Removed: 
    


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diff  --git a/clang/lib/Tooling/ExpandResponseFilesCompilationDatabase.cpp b/clang/lib/Tooling/ExpandResponseFilesCompilationDatabase.cpp
index 84936ba05b20..99298316718b 100644
--- a/clang/lib/Tooling/ExpandResponseFilesCompilationDatabase.cpp
+++ b/clang/lib/Tooling/ExpandResponseFilesCompilationDatabase.cpp
@@ -61,7 +61,9 @@ class ExpandResponseFilesDatabase : public CompilationDatabase {
       llvm::StringSaver Saver(Alloc);
       llvm::cl::ExpandResponseFiles(Saver, Tokenizer, Argv, false, false, *FS,
                                     llvm::StringRef(Cmd.Directory));
-      Cmd.CommandLine.assign(Argv.begin(), Argv.end());
+      // Don't assign directly, Argv aliases CommandLine.
+      std::vector<std::string> ExpandedArgv(Argv.begin(), Argv.end());
+      Cmd.CommandLine = std::move(ExpandedArgv);
     }
     return Cmds;
   }