That is true, but has nothing to do with "==" vs "=" vs ":=". You can do: func(x = 42); /* syntax error: expression operator expected, got '=' */ x = 42; /

That is true, but has nothing to do with "==" vs "=" vs ":=". You can do: func(x = 42); /* syntax error: expression operator expected, got '=' */ x = 42; /* OK */ x == 42; /* warning: statement expression has no effect */ just fine if you require "=" to be a statement.