Error with real-valued regular DO loop control variable

[svedan]

Failure with this test:

nag_f95_syntax/909t918.f90 error: Must have INTEGER type, but is REAL(4)

Per PKlausler: Error is legitimate due to the use of a real-valued I/O implied DO loop control variable. These have been invalid since at least F’90.
But since other compilers support this case, we need to add this as an extension.

[svedan]

Note the error is from semantics. So this will have to be addressed in the FE and in lowering.

[klausler]

This is an I/O implied DO loop, not a regular DO loop.