src: add CHECK_IMPLIES macro

This change introduces the CHECK_IMPLIES macro
similar to its definition in v8 and replaces instances of
CHECK with CHECK_IMPLIES where it seems appropriate.

PR-URL: #20914
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

Author: tniessen

src/callback_scope.cc

@@ -44,9 +44,7 @@ InternalCallbackScope::InternalCallbackScope(Environment* env,
     async_context_(asyncContext),
     object_(object),
     callback_scope_(env) {
-  if (expect == kRequireResource) {
-    CHECK(!object.IsEmpty());
-  }
+  CHECK_IMPLIES(expect == kRequireResource, !object.IsEmpty());
 
   if (!env->can_call_into_js()) {
     failed_ = true;

src/inspector_io.cc

@@ -197,7 +197,7 @@ bool InspectorIo::Start() {
 }
 
 void InspectorIo::Stop() {
-  CHECK(state_ == State::kAccepting || !sessions_.empty());
+  CHECK_IMPLIES(sessions_.empty(), state_ == State::kAccepting);
   Write(TransportAction::kKill, 0, StringView());
   int err = uv_thread_join(&thread_);
   CHECK_EQ(err, 0);

src/tls_wrap.cc

@@ -676,7 +676,7 @@ void TLSWrap::OnStreamRead(ssize_t nread, const uv_buf_t& buf) {
   if (!hello_parser_.IsEnded()) {
     size_t avail = 0;
     uint8_t* data = reinterpret_cast<uint8_t*>(enc_in->Peek(&avail));
-    CHECK(avail == 0 || data != nullptr);
+    CHECK_IMPLIES(data == nullptr, avail == 0);
     return hello_parser_.Parse(data, avail);
   }
 

src/util-inl.h

@@ -365,21 +365,21 @@ inline T* UncheckedCalloc(size_t n) {
 template <typename T>
 inline T* Realloc(T* pointer, size_t n) {
   T* ret = UncheckedRealloc(pointer, n);
-  if (n > 0) CHECK_NE(ret, nullptr);
+  CHECK_IMPLIES(n > 0, ret != nullptr);
   return ret;
 }
 
 template <typename T>
 inline T* Malloc(size_t n) {
   T* ret = UncheckedMalloc<T>(n);
-  if (n > 0) CHECK_NE(ret, nullptr);
+  CHECK_IMPLIES(n > 0, ret != nullptr);
   return ret;
 }
 
 template <typename T>
 inline T* Calloc(size_t n) {
   T* ret = UncheckedCalloc<T>(n);
-  if (n > 0) CHECK_NE(ret, nullptr);
+  CHECK_IMPLIES(n > 0, ret != nullptr);
   return ret;
 }
 

src/util.h

@@ -129,6 +129,7 @@ void DumpBacktrace(FILE* fp);
 #define CHECK_LE(a, b) CHECK((a) <= (b))
 #define CHECK_LT(a, b) CHECK((a) < (b))
 #define CHECK_NE(a, b) CHECK((a) != (b))
+#define CHECK_IMPLIES(a, b) CHECK(!(a) || (b))
 
 #define UNREACHABLE() ABORT()