Add [[nodiscard]] to GetParam() to prevent accidental misuse.

This helps avoid a situation where someone sets up a parameterized test but forgets to actually use the parameter.

PiperOrigin-RevId: 758455362
Change-Id: Ie4db03e82b6a4e1787be96f154b3fbb25657ae64

Author: mkruskal-google

googletest/include/gtest/gtest.h

@@ -1693,7 +1693,7 @@ class WithParamInterface {
 
   // The current parameter value. Is also available in the test fixture's
   // constructor.
-  static const ParamType& GetParam() {
+  [[nodiscard]] static const ParamType& GetParam() {
     GTEST_CHECK_(parameter_ != nullptr)
         << "GetParam() can only be called inside a value-parameterized test "
         << "-- did you intend to write TEST_P instead of TEST_F?";

googletest/test/googletest-param-test-test.cc

@@ -1174,7 +1174,7 @@ TEST_P(ParameterizedDerivedTest, SeesSequence) {
 class ParameterizedDeathTest : public ::testing::TestWithParam<int> {};
 
 TEST_F(ParameterizedDeathTest, GetParamDiesFromTestF) {
-  EXPECT_DEATH_IF_SUPPORTED(GetParam(), ".* value-parameterized test .*");
+  EXPECT_DEATH_IF_SUPPORTED((void)GetParam(), ".* value-parameterized test .*");
 }
 
 INSTANTIATE_TEST_SUITE_P(RangeZeroToFive, ParameterizedDerivedTest,