[flang] Incorrect warning message about default integer kind

[DanielCChen]

Consider the following reducer

  PROGRAM  main
  IMPLICIT NONE

  INTEGER(1), PARAMETER :: I1Max=127

  INTEGER(2), PARAMETER :: I2Max=32767

  print*, I2Max+I1Max-1          

  END

Flang complains:

./t.f:8:12: warning: INTEGER(2) addition overflowed [-Wfolding-exception]
    print*, (I2Max+I1Max-1)
             ^^^^^^^^^^^

The result integer kind of the expression should be default integer kind, which is 4.
The error message seems incorrect, which also caused incorrect run result.

[llvmbot]

@llvm/issue-subscribers-flang-frontend

Author: Daniel Chen (DanielCChen)

Consider the following reducer ``` PROGRAM main IMPLICIT NONE

INTEGER(1), PARAMETER :: I1Max=127

INTEGER(2), PARAMETER :: I2Max=32767

print*, I2Max+I1Max-1

END

Flang complains:

./t.f:8:12: warning: INTEGER(2) addition overflowed [-Wfolding-exception]
print*, (I2Max+I1Max-1)
^^^^^^^^^^^

The result integer kind should be default integer kind, which is 4.
The error message seems incorrect, which also caused incorrect run result.
</details>

[DanielCChen]

The KIND parameter of the expression seems based on the kind of the first operand.