[llvm] [LLVM][Coverage][Unittest] Fix dangling reference in unittest (PR #147118)

[Ellis Hoag via llvm-commits]

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@@ -233,13 +235,10 @@ struct CoverageMappingTest : ::testing::TestWithParam<std::tuple<bool, bool>> {
 
   void readCoverageRegions(const std::string &Coverage,
                            OutputFunctionCoverageData &Data) {
-    // We will re-use the StringRef in duplicate tests, clear it to avoid
-    // clobber previous ones.
-    Filenames.clear();
-    Filenames.resize(Files.size() + 1);
+    Data.FilenamesStorage.resize(Files.size() + 1);
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ellishg wrote:

Why `+ 1`?

https://github.com/llvm/llvm-project/pull/147118