[llvm] [libcxx] [libc++][NFC] Make AssertionInfoMatcher::CheckMessageMatches Stricter (PR #77721)

[Will Hawkins via llvm-commits]

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@@ -89,8 +89,7 @@ struct AssertionInfoMatcher {
     std::size_t found_at = got_msg.find(msg_);
     if (found_at == std::string_view::npos)
       return false;
-    // Allow any match
-    return true;
+    return found_at == 0 && got_msg.size() == msg_.size();
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hawkinsw wrote:

Thanks!!

https://github.com/llvm/llvm-project/pull/77721