Handle functions outside namespaces in GetFunctionName().

In the debug mode, the string containing the symbolized function name starts
with the path to the source file and the line number of the function. If the
function is not in an anonymous namespace, those incorrectly get printed out
as part of the function name.

PiperOrigin-RevId: 679602262

fuzztest/internal/type_support.h

@@ -335,6 +335,31 @@ constexpr bool HasFunctionName() {
   return std::is_function_v<std::remove_pointer_t<F>>;
 }
 
+inline void ConsumeFileAndLineNumber(absl::string_view& v) {
+  // We're essentially matching the regexp "[^:]\:\d+ ", but manually since we
+  // don't want to introduce a dependency on RE2.
+  absl::string_view::size_type pos = 0;
+  while (pos < v.size()) {
+    pos = v.find(':', pos);
+    if (pos == v.npos) return;
+    // Skip the colon.
+    ++pos;
+    if (pos >= v.size() || !std::isdigit(v[pos])) {
+      // Colon not followed by a digit. Skip any subsequent colons and continue.
+      while (pos < v.size() && v[pos] == ':') ++pos;
+      continue;
+    }
+    // Skip the digits.
+    ++pos;
+    while (pos < v.size() && std::isdigit(v[pos])) ++pos;
+    if (pos >= v.size() || v[pos] != ' ') continue;
+    // Skip the space.
+    ++pos;
+    v.remove_prefix(pos);
+    return;
+  }
+}
+
 template <typename F>
 std::string GetFunctionName(const F& f, absl::string_view default_name) {
   if constexpr (HasFunctionName<F>()) {
@@ -343,6 +368,7 @@ std::string GetFunctionName(const F& f, absl::string_view default_name) {
                         sizeof(buffer))) {
       absl::string_view v = buffer;
       absl::ConsumeSuffix(&v, "()");
+      ConsumeFileAndLineNumber(v);
       SkipAnonymous(v);
       return std::string(v);
     }

fuzztest/internal/type_support_test.cc

@@ -383,6 +383,26 @@ TEST(MapTest, Printer) {
               Each("\"0x15\""));
 }
 
+}  // namespace
+}  // namespace fuzztest::internal
+
+auto DoubleValueOutsideNamespace(int n) { return 2 * n; }
+
+namespace fuzztest::internal {
+namespace {
+
+TEST(MapTest, PrintsMapperOutsideNamespace) {
+  auto domain = Map(DoubleValueOutsideNamespace, InRange(2, 5));
+  std::tuple<int> corpus_value(3);
+
+  EXPECT_THAT(
+      TestPrintValue(corpus_value, domain),
+      ElementsAre("6",
+                  // Takes into account that the function name may
+                  // contain ABI annotations after de-mangling.
+                  MatchesRegex(R"re(DoubleValueOutsideNamespace.*\(3\))re")));
+}
+
 auto ValueInRange(int a, int b) {
   int min = std::min(a, b);
   int max = std::max(a, b);