src: replace unreachable code with static_assert

This function divides an unsigned 32-bit integer by 8, effectively
right-shifting it by three bits, so the result must be less than
INT_MAX.

Refs: #46209
PR-URL: #46250
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

src/crypto/crypto_keygen.cc

@@ -16,7 +16,6 @@ using v8::Int32;
 using v8::Just;
 using v8::Local;
 using v8::Maybe;
-using v8::Nothing;
 using v8::Object;
 using v8::Uint32;
 using v8::Value;
@@ -62,15 +61,11 @@ Maybe<bool> SecretKeyGenTraits::AdditionalConfig(
     const FunctionCallbackInfo<Value>& args,
     unsigned int* offset,
     SecretKeyGenConfig* params) {
-  Environment* env = Environment::GetCurrent(args);
   CHECK(args[*offset]->IsUint32());
-  params->length = args[*offset].As<Uint32>()->Value() / CHAR_BIT;
-  if (params->length > INT_MAX) {
-    THROW_ERR_OUT_OF_RANGE(env,
-                           "length must be less than or equal to %u bits",
-                           static_cast<uint64_t>(INT_MAX) * CHAR_BIT);
-    return Nothing<bool>();
-  }
+  uint32_t bits = args[*offset].As<Uint32>()->Value();
+  static_assert(std::numeric_limits<decltype(bits)>::max() / CHAR_BIT <=
+                INT_MAX);
+  params->length = bits / CHAR_BIT;
   *offset += 1;
   return Just(true);
 }