[mesa-users] Inline Comments in Namelists

[Josiah Schwab]

Hi All,

Did you know that inline comments in namelists are treated differently
than in the body of a program in a compiler-dependent way?  I didn't!

For example, in a fortran program an assignment of the form

  val = 3.14!2.78

obviously assigns the value 3.14 to the variable val.

If you write the same thing in a fortran namelist (an inlist),

  + with ifort, it behaves as you would naively expect
  + with gfortran, whole line is is effectively ignored

I've attached a trivial test program that demonstrates this.


GNU Fortran (GCC) 4.9.3 20141212 (prerelease)
,----
| henyey: ~$ gfortran -o test.x test_namelist.f90 && ./test.x
| 
| assign: val =  3.14
| namelist: val = -1.00
`----

ifort (IFORT) 14.0.2 20140120
,----
| henyey: ~$ ifort -o test.x test_namelist.f90 && ./test.x
|
| assign: val =  3.14
| namelist: val =  3.14
`----

I spent a while today chasing a problem that boiled down to this
peculiarity.  I figured I'd send a mail so that someday someone will
think of this more quickly than I did.

I tried looking up the standard, but couldn't find anything specific
enough to tell whether this behavior is specified or undefined.

Best,
Josiah

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