[patch,fortran] PR33268 read ('(f3.3)'), a rejected due to the extra (...)

[Jerry DeLisle]

Jerry DeLisle wrote:
> Hi Folks,
> 
> This patch provides for the "format" form of the READ and PRINT 
> statements.  By "format" form I mean with no UNIT specified. The patch 
> also rejects the WRITE statement with this form.  See section 9.5 of the 
> F2003 Standard.
> 
> By example:
> 
> print('a'), 'Hello'       ! Invalid, missing parens inside format string
> write(*,('(a)')) 'Hello'  ! Valid
> write (*,'(f8.3)'), 3.141597  ! Extension, comma after the ')'
> write ('(a)'), "invalid"  ! Invalid, "format" form not allowed for WRITE
> print ('(a)'), "valid"    ! Valid, "format" form accepted
> read ('(f3.3)')), a       ! Valid, "format form accepted
> 
> To accomplish this, I added a new expression pointer, extra_comma, to 
> pass the io_kind and locus to gfc_resolve_dt.  If this pointer is 
> non-NULL, it indicates that an extra comma preceding the I/O list was 
> encountered.  This signals a possible alternate form of the I/O statement.
> 
> If the alternate form was used, the io_unit expression will come in as a 
> character type of expression.  If so, it is assumed to be a format 
> expression and not a unit, and the pointers involved are adjusted so 
> that the format expression refers to the character expression in 
> io_unit, and the io_unit is pointed to the default unit for the io_kind.
> 
> The io_kind is passed in extra_comma->value.logical.  I used this since 
> it is an int and can hold the enumerator type without problem.  Another 
> option would be to add "io_kind k" to the union for value in gfc_expr, 
> giving more readable code.
> 
> Regression tested on x86-64.
> 
> OK for trunk?
> 
ping