Mismatch between constant pattern and value typeDRT-W1263

The analyzer produces this diagnostic when a constant pattern can never match the value it's being tested against because the type of the constant is known to never match the type of the value.

Example

The following code produces this diagnostic because the type of the constant pattern (true) is bool, and the type of the value being matched (x) is int, and a Boolean can never match an integer:

void f(int x) {
  if (x case true) {}
}

Common fixes

If the type of the value is correct, then rewrite the pattern to be compatible:

void f(int x) {
  if (x case 3) {}
}

If the type of the constant is correct, then rewrite the value to be compatible:

void f(bool x) {
  if (x case true) {}
}