Fix a min-max bug

[Liuyunlong0336]

This patch solves two problems:

1. According to the fortran 2008 standard, add syntax check for MAX/MIN intrinsic, as follows:

   The arguments shall all be of the same type which shall be integer, real, or character and they shall all have the same kind type parameter.

2. The final type of argument with MIN/MAX intrinsic is determined by the type of highest precision argument, not the first argument.

[bryanpkc]

The code doesn't compile. Did you push an incomplete patch?

[bryanpkc]

Can you clarify why the argument type checks and promotion cannot be done for I_MAX and I_MIN in the intrinsic_error block? It semes that that block of code was designed to handle these two intrinsics.

[Liuyunlong0336]

The logic in this function is relatively complex.

For intrinsic_error ,these situations will occur:

The first scenario is as follows：

program test
  implicit none
  integer :: a, b, c
  a = 1
  b = 2
  c = max(a)
end program test

The second scenario is as follows：

program test
  implicit none
  integer :: a, b, c
  a = 1
  b = 2
  c = max()
end program test

I understand that when there is an obvious error in the arguments, there are no arguments or the arguments number is wrong, in this case intrinsic_error will be called.

And For logic in the intrinsic_error block, it is prepared for generic situations：
As follows:

/* Need to add a check for min and max first */
if (STYPEG(sptre) == ST_GENERIC && (intrin == I_MAX || intrin == I_MIN)) {

So I don’t dare to modify this logic.

And For our case, for example, argument type program will not trigger intrinsic_error.
For example:

program test
  implicit none
  integer :: a, c
  real :: b
  a = 1
  b = 2
  c = max(a, b)
end program test

In this case, the compilation can still pass, but the native version of the compiler will occur a warning.

F90-W-0093-Type conversion of expression performed

This is what a general check of this logic reports，chktyp(sp, argtyp, TRUE); in this logic will be checked, and this check is for many kinds of intrinsics.

             if (((intrin == I_BGE) || (intrin == I_BGT) ||
                  (intrin == I_BLE) || (intrin == I_BLT)) &&
                 (SST_IDG(sp) == S_CONST || SST_IDG(sp) == S_IDENT)) {
               mkexpr1(sp);
             } else
               chktyp(sp, argtyp, TRUE);

So I haven’t found a perfect method yet. For type judgment and type selection, I chose to add judgment and type update logic in front like this PR.

[pawosm-arm]

a small typo in the commit message: precision atgument vs. precision argument

[pawosm-arm]

Anything happens here?