Add NXT_UNUSED to silence unused warnings

src/common/Assert.h

@@ -55,7 +55,7 @@
 #    else
 #        define NXT_ASSERT_CALLSITE_HELPER(file, func, line, condition) \
             do {                                                        \
-                (void)sizeof(condition);                                \
+                NXT_UNUSED(sizeof(condition));                          \
             } while (NXT_ASSERT_LOOP_CONDITION)
 #    endif
 #endif

src/common/Compiler.h

@@ -22,6 +22,7 @@
 //  - NXT_NO_DISCARD: An attribute that is C++17 [[nodiscard]] where available
 //  - NXT_(UN)?LIKELY(EXPR): Where available, hints the compiler that the expression will be true
 //      (resp. false) to help it generate code that leads to better branch prediction.
+//  - NXT_UNUSED(EXPR): Prevents unused variable/expression warnings on EXPR.
 
 // Clang and GCC
 #if defined(__GNUC__)
@@ -72,6 +73,9 @@ extern void __cdecl __debugbreak(void);
 #    error "Unsupported compiler"
 #endif
 
+// It seems that (void) EXPR works on all compilers to silence the unused variable warning.
+#define NXT_UNUSED(EXPR) (void)EXPR
+
 // Add noop replacements for macros for features that aren't supported by the compiler.
 #if !defined(NXT_LIKELY)
 #    define NXT_LIKELY(X) X

src/tests/unittests/BitSetIteratorTests.cpp

@@ -51,7 +51,7 @@ TEST_F(BitSetIteratorTest, EmptySet) {
     // causing an unreachable code warning in MSVS
     bool sawBit = false;
     for (unsigned long bit : IterateBitSet(mStateBits)) {
-        (void) bit;
+        NXT_UNUSED(bit);
         sawBit = true;
     }
     EXPECT_FALSE(sawBit);

src/tests/unittests/ErrorTests.cpp

@@ -178,7 +178,7 @@ TEST(ErrorTests, TRY_RESULT_Error) {
     auto Try = [ReturnError]() -> ResultOrError<int*> {
         int* result = nullptr;
         NXT_TRY_ASSIGN(result, ReturnError());
-        (void) result;
+        NXT_UNUSED(result);
 
         // NXT_TRY should return before this point
         EXPECT_FALSE(true);
@@ -233,7 +233,7 @@ TEST(ErrorTests, TRY_RESULT_ConversionToError) {
     auto Try = [ReturnError]() -> MaybeError {
         int* result = nullptr;
         NXT_TRY_ASSIGN(result, ReturnError());
-        (void) result;
+        NXT_UNUSED(result);
 
         return {};
     };

src/tests/unittests/SerialQueueTests.cpp

@@ -27,7 +27,7 @@ TEST(SerialQueue, BasicTest) {
 
     // Iterating on empty queue 1) works 2) doesn't produce any values
     for (int value : queue.IterateAll()) {
-        (void) value;
+        NXT_UNUSED(value);
         ASSERT_TRUE(false);
     }
 
@@ -50,7 +50,7 @@ TEST(SerialQueue, BasicTest) {
     ASSERT_TRUE(queue.Empty());
 
     for (int value : queue.IterateAll()) {
-        (void) value;
+        NXT_UNUSED(value);
         ASSERT_TRUE(false);
     }
 }