[PATCH] D105120: [clang] Fix UB when string.front() is used for the empty string

[Dmitry Polukhin via Phabricator via cfe-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rGfceaf8621179: [clang] Fix UB when string.front() is used for the empty string (authored by DmitryPolukhin).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D105120/new/

https://reviews.llvm.org/D105120

Files:
  clang/lib/Tooling/ExpandResponseFilesCompilationDatabase.cpp
  clang/unittests/Tooling/CompilationDatabaseTest.cpp


Index: clang/unittests/Tooling/CompilationDatabaseTest.cpp
===================================================================
--- clang/unittests/Tooling/CompilationDatabaseTest.cpp
+++ clang/unittests/Tooling/CompilationDatabaseTest.cpp
@@ -700,6 +700,10 @@
     SmallVector<StringRef, 8> Argv = {Clang, File, "-D", File};
     llvm::SplitString(Flags, Argv);
 
+    // Trim double quotation from the argumnets if any.
+    for (auto *It = Argv.begin(); It != Argv.end(); ++It)
+      *It = It->trim("\"");
+
     SmallString<32> Dir;
     llvm::sys::path::system_temp_directory(false, Dir);
 
@@ -962,5 +966,12 @@
   EXPECT_EQ(getCommand("bar.cpp"), "clang bar.cpp -D bar.cpp -Dflag");
 }
 
+TEST_F(ExpandResponseFilesTest, ExpandResponseFilesEmptyArgument) {
+  addFile(path(StringRef("rsp1.rsp")), "-Dflag");
+
+  add("foo.cpp", "clang", "@rsp1.rsp \"\"");
+  EXPECT_EQ(getCommand("foo.cpp"), "clang foo.cpp -D foo.cpp -Dflag ");
+}
+
 } // end namespace tooling
 } // end namespace clang
Index: clang/lib/Tooling/ExpandResponseFilesCompilationDatabase.cpp
===================================================================
--- clang/lib/Tooling/ExpandResponseFilesCompilationDatabase.cpp
+++ clang/lib/Tooling/ExpandResponseFilesCompilationDatabase.cpp
@@ -54,7 +54,8 @@
       Argv.reserve(Cmd.CommandLine.size());
       for (auto &Arg : Cmd.CommandLine) {
         Argv.push_back(Arg.c_str());
-        SeenRSPFile |= Arg.front() == '@';
+        if (!Arg.empty())
+          SeenRSPFile |= Arg.front() == '@';
       }
       if (!SeenRSPFile)
         continue;


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