[clang] [Format] Do not crash on non-null terminated strings (PR #131299)

[Owen Pan via cfe-commits]

================
@@ -29096,6 +29096,17 @@ TEST_F(FormatTest, BreakBeforeClassName) {
                "    ArenaSafeUniquePtr {};");
 }
 
+TEST_F(FormatTest, DoesNotCrashOnNonNullTerminatedStringRefs) {
+  llvm::StringRef TwoLines = "namespace foo {}\n"
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owenca wrote:

```suggestion
  StringRef TwoLines = "namespace foo {}\n"
```

https://github.com/llvm/llvm-project/pull/131299