[libc] Add -Wextra for libc tests (#133643)

* Relates to: #119281

Author: vinay-deshmukh

libc/cmake/modules/LLVMLibCTestRules.cmake

@@ -40,7 +40,7 @@ function(_get_common_test_compile_options output_var c_test flags)
     endif()
 
     # list(APPEND compile_options "-Wall")
-    # list(APPEND compile_options "-Wextra")
+    list(APPEND compile_options "-Wextra")
     # -DLIBC_WNO_ERROR=ON if you can't build cleanly with -Werror.
     if(NOT LIBC_WNO_ERROR)
       # list(APPEND compile_options "-Werror")

libc/test/UnitTest/FPExceptMatcher.cpp

@@ -31,7 +31,7 @@ namespace testing {
 static thread_local sigjmp_buf jumpBuffer;
 static thread_local bool caughtExcept;
 
-static void sigfpeHandler(int sig) {
+static void sigfpeHandler([[maybe_unused]] int sig) {
   caughtExcept = true;
   siglongjmp(jumpBuffer, -1);
 }

libc/test/UnitTest/FPExceptMatcher.h

@@ -43,7 +43,7 @@ class FPExceptMatcher : public Matcher<bool> {
   // Takes ownership of func.
   explicit FPExceptMatcher(FunctionCaller *func);
 
-  bool match(bool unused) { return exceptionRaised; }
+  bool match([[maybe_unused]] bool unused) { return exceptionRaised; }
 
   void explainError() override {
     tlog << "A floating point exception should have been raised but it "

libc/test/UnitTest/HermeticTestUtils.cpp

@@ -29,7 +29,9 @@ int atexit(void (*func)(void));
 // add_libc_hermetic_test properly. Such that they won't get correct linkage
 // against the object containing this function. We create a dummy function that
 // always returns 0 to indicate a failure.
-[[gnu::weak]] unsigned long getauxval(unsigned long id) { return 0; }
+[[gnu::weak]] unsigned long getauxval([[maybe_unused]] unsigned long id) {
+  return 0;
+}
 
 } // namespace LIBC_NAMESPACE_DECL
 
@@ -124,7 +126,7 @@ unsigned long __getauxval(unsigned long id) {
 
 } // extern "C"
 
-void *operator new(size_t size, void *ptr) { return ptr; }
+void *operator new([[maybe_unused]] size_t size, void *ptr) { return ptr; }
 
 void *operator new(size_t size) { return malloc(size); }
 
@@ -136,7 +138,9 @@ void operator delete(void *) {
   __builtin_trap();
 }
 
-void operator delete(void *ptr, size_t size) { __builtin_trap(); }
+void operator delete([[maybe_unused]] void *ptr, [[maybe_unused]] size_t size) {
+  __builtin_trap();
+}
 
 // Defining members in the std namespace is not preferred. But, we do it here
 // so that we can use it to define the operator new which takes std::align_val_t
@@ -145,8 +149,11 @@ namespace std {
 enum class align_val_t : size_t {};
 } // namespace std
 
-void operator delete(void *mem, std::align_val_t) noexcept { __builtin_trap(); }
+void operator delete([[maybe_unused]] void *mem, std::align_val_t) noexcept {
+  __builtin_trap();
+}
 
-void operator delete(void *mem, unsigned int, std::align_val_t) noexcept {
+void operator delete([[maybe_unused]] void *mem, unsigned int,
+                     std::align_val_t) noexcept {
   __builtin_trap();
 }

libc/test/UnitTest/LibcDeathTestExecutors.cpp

@@ -22,7 +22,8 @@ namespace LIBC_NAMESPACE_DECL {
 namespace testing {
 
 bool Test::testProcessKilled(testutils::FunctionCaller *Func, int Signal,
-                             const char *LHSStr, const char *RHSStr,
+                             const char *LHSStr,
+                             [[maybe_unused]] const char *RHSStr,
                              internal::Location Loc) {
   testutils::ProcessStatus Result =
       testutils::invoke_in_subprocess(Func, TIMEOUT_MS);

libc/test/UnitTest/LibcTest.h

@@ -81,7 +81,7 @@ struct Message {
 // A trivial object to catch the Message, this enables custom logging and
 // returning from the test function, see LIBC_TEST_SCAFFOLDING_ below.
 struct Failure {
-  void operator=(Message msg) {}
+  void operator=([[maybe_unused]] Message msg) {}
 };
 
 struct RunContext {

libc/test/include/stdbit_stub.h

@@ -17,11 +17,21 @@
 #include <stdbool.h> // bool in C
 
 #define STDBIT_STUB_FUNCTION(FUNC_NAME, LEADING_VAL)                           \
-  unsigned FUNC_NAME##_uc(unsigned char x) { return LEADING_VAL##AU; }         \
-  unsigned FUNC_NAME##_us(unsigned short x) { return LEADING_VAL##BU; }        \
-  unsigned FUNC_NAME##_ui(unsigned int x) { return LEADING_VAL##CU; }          \
-  unsigned FUNC_NAME##_ul(unsigned long x) { return LEADING_VAL##DU; }         \
-  unsigned FUNC_NAME##_ull(unsigned long long x) { return LEADING_VAL##EU; }
+  unsigned FUNC_NAME##_uc([[maybe_unused]] unsigned char x) {                  \
+    return LEADING_VAL##AU;                                                    \
+  }                                                                            \
+  unsigned FUNC_NAME##_us([[maybe_unused]] unsigned short x) {                 \
+    return LEADING_VAL##BU;                                                    \
+  }                                                                            \
+  unsigned FUNC_NAME##_ui([[maybe_unused]] unsigned int x) {                   \
+    return LEADING_VAL##CU;                                                    \
+  }                                                                            \
+  unsigned FUNC_NAME##_ul([[maybe_unused]] unsigned long x) {                  \
+    return LEADING_VAL##DU;                                                    \
+  }                                                                            \
+  unsigned FUNC_NAME##_ull([[maybe_unused]] unsigned long long x) {            \
+    return LEADING_VAL##EU;                                                    \
+  }
 
 __BEGIN_C_DECLS
 
@@ -36,24 +46,42 @@ STDBIT_STUB_FUNCTION(stdc_first_trailing_one, 0x1)
 STDBIT_STUB_FUNCTION(stdc_count_zeros, 0x2)
 STDBIT_STUB_FUNCTION(stdc_count_ones, 0x3)
 
-bool stdc_has_single_bit_uc(unsigned char x) { return false; }
-bool stdc_has_single_bit_us(unsigned short x) { return false; }
-bool stdc_has_single_bit_ui(unsigned x) { return false; }
-bool stdc_has_single_bit_ul(unsigned long x) { return false; }
-bool stdc_has_single_bit_ull(unsigned long long x) { return false; }
+bool stdc_has_single_bit_uc([[maybe_unused]] unsigned char x) { return false; }
+bool stdc_has_single_bit_us([[maybe_unused]] unsigned short x) { return false; }
+bool stdc_has_single_bit_ui([[maybe_unused]] unsigned x) { return false; }
+bool stdc_has_single_bit_ul([[maybe_unused]] unsigned long x) { return false; }
+bool stdc_has_single_bit_ull([[maybe_unused]] unsigned long long x) {
+  return false;
+}
 
 STDBIT_STUB_FUNCTION(stdc_bit_width, 0x4)
 
-unsigned char stdc_bit_floor_uc(unsigned char x) { return 0x5AU; }
-unsigned short stdc_bit_floor_us(unsigned short x) { return 0x5BU; }
-unsigned stdc_bit_floor_ui(unsigned x) { return 0x5CU; }
-unsigned long stdc_bit_floor_ul(unsigned long x) { return 0x5DUL; }
-unsigned long long stdc_bit_floor_ull(unsigned long long x) { return 0x5EULL; }
-
-unsigned char stdc_bit_ceil_uc(unsigned char x) { return 0x6AU; }
-unsigned short stdc_bit_ceil_us(unsigned short x) { return 0x6BU; }
-unsigned stdc_bit_ceil_ui(unsigned x) { return 0x6CU; }
-unsigned long stdc_bit_ceil_ul(unsigned long x) { return 0x6DUL; }
-unsigned long long stdc_bit_ceil_ull(unsigned long long x) { return 0x6EULL; }
+unsigned char stdc_bit_floor_uc([[maybe_unused]] unsigned char x) {
+  return 0x5AU;
+}
+unsigned short stdc_bit_floor_us([[maybe_unused]] unsigned short x) {
+  return 0x5BU;
+}
+unsigned stdc_bit_floor_ui([[maybe_unused]] unsigned x) { return 0x5CU; }
+unsigned long stdc_bit_floor_ul([[maybe_unused]] unsigned long x) {
+  return 0x5DUL;
+}
+unsigned long long stdc_bit_floor_ull([[maybe_unused]] unsigned long long x) {
+  return 0x5EULL;
+}
+
+unsigned char stdc_bit_ceil_uc([[maybe_unused]] unsigned char x) {
+  return 0x6AU;
+}
+unsigned short stdc_bit_ceil_us([[maybe_unused]] unsigned short x) {
+  return 0x6BU;
+}
+unsigned stdc_bit_ceil_ui([[maybe_unused]] unsigned x) { return 0x6CU; }
+unsigned long stdc_bit_ceil_ul([[maybe_unused]] unsigned long x) {
+  return 0x6DUL;
+}
+unsigned long long stdc_bit_ceil_ull([[maybe_unused]] unsigned long long x) {
+  return 0x6EULL;
+}
 
 __END_C_DECLS

libc/test/integration/src/pthread/pthread_mutex_test.cpp

@@ -23,7 +23,7 @@ constexpr int MAX = 10000;
 pthread_mutex_t mutex;
 static int shared_int = START;
 
-void *counter(void *arg) {
+void *counter([[maybe_unused]] void *arg) {
   int last_count = START;
   while (true) {
     LIBC_NAMESPACE::pthread_mutex_lock(&mutex);
@@ -72,7 +72,7 @@ void relay_counter() {
 pthread_mutex_t start_lock, step_lock;
 bool started, step;
 
-void *stepper(void *arg) {
+void *stepper([[maybe_unused]] void *arg) {
   LIBC_NAMESPACE::pthread_mutex_lock(&start_lock);
   started = true;
   LIBC_NAMESPACE::pthread_mutex_unlock(&start_lock);

libc/test/integration/src/spawn/posix_spawn_test.cpp

@@ -45,7 +45,8 @@ void spawn_and_wait_for_normal_exit(char **envp) {
   ASSERT_EQ(exit_status, 0);
 }
 
-TEST_MAIN(int argc, char **argv, char **envp) {
+TEST_MAIN([[maybe_unused]] int argc, [[maybe_unused]] char **argv,
+          char **envp) {
   spawn_and_wait_for_normal_exit(envp);
   return 0;
 }

libc/test/integration/src/spawn/posix_spawn_test_binary.cpp

@@ -2,7 +2,7 @@
 #include <string.h>
 #include <unistd.h>
 
-int main(int argc, char **argv) {
+int main(int argc, [[maybe_unused]] char **argv) {
   if (argc != 1)
     return 5;
   constexpr size_t bufsize = sizeof(TEXT);