E2026 Constant expression expected (Object Pascal)
The compiler expected a constant expression here, but the expression it found turned out not to be constant.
program Produce; const Message = 'Hello World!'; WPosition = Pos('W', Message); begin end.
The call to Pos is not a constant expression to the compiler, even though its arguments are constants, and it could in principle be evaluated at compile time.
program Solve; const Message = 'Hello World!'; WPosition = 7; begin end.
So in this case, we just have to calculate the right value for WPosition ourselves.