Add MSAN support with a functional test.

PiperOrigin-RevId: 800008865

e2e_tests/testdata/fuzz_tests_for_microbenchmarking.cc

diff --git a/e2e_tests/testdata/fuzz_tests_for_microbenchmarking.cc b/e2e_tests/testdata/fuzz_tests_for_microbenchmarking.cc
index 1282a92..f1c7d63 100644
--- a/e2e_tests/testdata/fuzz_tests_for_microbenchmarking.cc
+++ b/e2e_tests/testdata/fuzz_tests_for_microbenchmarking.cc
@@ -27,6 +27,7 @@
 #include <array>
 #include <cmath>
 #include <cstdint>
+#include <cstdio>
 #include <cstdlib>
 #include <optional>
 #include <string>
@@ -87,6 +88,15 @@
 }
 FUZZ_TEST(MySuite, DereferenceEmptyOptional);
 
+// We use this test to make sure we catch reading uninitialized memory.
+void UninitializedReadWithString(const std::string& s) {
+  if (s.empty()) return;
+  volatile uint8_t uninitialized_memory[1];
+  printf("Read byte %x\n", uninitialized_memory[0]);
+}
+FUZZ_TEST(MySuite, UninitializedReadWithString)
+    .WithDomains(fuzztest::Arbitrary<std::string>());
+
 // Always disable optimization for this example, otherwise (when optimization is
 // enabled) SanCov doesn't instrument all edges (and therefore no feedback).
 // TODO(b/182297432): Make this unnecessary.