[flang] I/O Runtime failure with `BLANK=zero` in READ

[DanielCChen]

Consider the following code:

      implicit none

      integer, parameter :: in = 11

      real(4)    :: rl4
      real(8)    :: rl8
      complex(4) :: cx4
      complex(8) :: cx8

      open(in, file='modeBlankNaNInfIO002.dat', blank='zero')

      ! read the values in using BLANK mode of ZERO
      read(in, *, blank='zero')  rl4, rl8, cx4, cx8

      ! read the values in using BLANK mode of NULL
      read(in, *, blank='null')  rl4, rl8, cx4, cx8

      ! read the values in using BLANK mode of ZERO
      read(in, *, blank='zero')  rl4, rl8, cx4, cx8

      close(in)

      end

The modeBlankNaNInfIO002.dat is:

 -NaN(Q)   -NaN(S)   (  +Inf  ,+3.14  ) (Infinity   ,  NaN(_abcd123)   )
 -NaN(Q)   -NaN(S)   (  +Inf  ,+3.14  ) (Infinity   ,  NaN(_abcd123)   )
  +NaN(S)   +NaN(Q)   (  -3.14  ,  -NaN()  ) (  -Infinity , nan )
  +NaN(S)   +NaN(Q)   (  -3.14  ,  -NaN()  ) (  -Infinity , nan )

Flang failed at execution as:

> a.out

fatal Fortran runtime error(t.f:19): Bad real input data at column 44 of record 3
IOT/Abort trap(coredump)

Both gfortran and XLF executes the code successfully.

If I remove all of the blank= specifier from the open and read statements, it works fine.

[llvmbot]

@llvm/issue-subscribers-flang-runtime

Author: Daniel Chen (DanielCChen)

Consider the following code: ``` implicit none

  integer, parameter :: in = 11

  real(4)    :: rl4
  real(8)    :: rl8
  complex(4) :: cx4
  complex(8) :: cx8

  open(in, file='modeBlankNaNInfIO002.dat', blank='zero')

  ! read the values in using BLANK mode of ZERO
  read(in, *, blank='zero')  rl4, rl8, cx4, cx8

  ! read the values in using BLANK mode of NULL
  read(in, *, blank='null')  rl4, rl8, cx4, cx8

  ! read the values in using BLANK mode of ZERO
  read(in, *, blank='zero')  rl4, rl8, cx4, cx8

  close(in)

  end

The `modeBlankNaNInfIO002.dat` is:

-NaN(Q) -NaN(S) ( +Inf ,+3.14 ) (Infinity , NaN(_abcd123) )
-NaN(Q) -NaN(S) ( +Inf ,+3.14 ) (Infinity , NaN(_abcd123) )
+NaN(S) +NaN(Q) ( -3.14 , -NaN() ) ( -Infinity , nan )
+NaN(S) +NaN(Q) ( -3.14 , -NaN() ) ( -Infinity , nan )

Flang failed at execution as:

> a.out

fatal Fortran runtime error(t.f:19): Bad real input data at column 44 of record 3
IOT/Abort trap(coredump)

Both gfortran and XLF executes the code successfully.

If I remove all of the `blank=` specifier from the `open` and `read` statements, it works fine.
</details>

[eugeneepshteyn]

@DanielCChen , is this with Peter's #149606 change applied to flang?

[DanielCChen]

@DanielCChen , is this with Peter's #149606 change applied to flang?

Correct. This error is after I applied Peter's fix in #149606. Note that Flang is now complaining about the 3rd record. Peter's fix allows Flang parsing the first 2 records.

[klausler]

Works now with latest #149606.

[DanielCChen]

Fixed by the latest patch of #149606.