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Aug 3, 2025
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Fortran does not guarantee logical AND short circuit #189

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7 changes: 7 additions & 0 deletions DEVELOPER_NOTES.md
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Original file line number Diff line number Diff line change
Expand Up @@ -929,4 +929,11 @@ The problem is reported in https://llvm.org/bugs/show_bug.cgi?id=14713
through the ncmpio driver directly.

---
### Note on Fortran programming
* Unlike C, the Fortran standard does not mandate or prohibit short-circuit
evaluation for logical expressions. Thus, Fortran does not guarantee that
the .AND. operator will skip evaluating the second logical expression if
the first one is false. See PR #189.

---

19 changes: 14 additions & 5 deletions test/nf_test/test_write.F
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Expand Up @@ -539,11 +539,20 @@ subroutine test_nfmpi_abort()
err = nfmpi_inq_file_info(ncid, infoused)
if (err .eq. NF_NOERR) then
call MPI_Info_get(infoused, "nc_burst_buf",
+ MPI_MAX_INFO_VAL, hint, flag, err)
if (flag .AND. hint .EQ. 'enable') then
err = nfmpi_flush(ncid)
if (err .ne. NF_NOERR)
+ call errore('nfmpi_flush: ', err)
+ MPI_MAX_INFO_VAL-1, hint, flag, err)
! The Fortran standard does not mandate or prohibit
! short-circuit evaluation for logical expressions.
! Fortran does not guarantee that the .and. operator will
! skip evaluating the second logical expression if the
! first one is false.
!
! if (flag .AND. hint .EQ. 'enable') then
if (flag) then
if (hint .EQ. 'enable') then
err = nfmpi_flush(ncid)
if (err .ne. NF_NOERR)
+ call errore('nfmpi_flush: ', err)
endif
endif
call MPI_Info_free(infoused, err);
endif
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