https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94110
--- Comment #2 from José Rui Faustino de Sousa <jrfsousa at gmail dot com> --- Hi Thomas! IIRC assumed-size arrays are implemented has packaged descriptor less arrays. In order to point to them or to pass them to a procedure expecting an assumed or deferred-shape array one has to create an array descriptor. To create such descriptor one must know the array bounds, which one does not for assumed-size arrays. Fortran pointers, unlike their C brethren, also carry bound information and AFAIK one can not have an array, or a pointer to an array, which has undefined bounds (what would the intrinsics like shape, ubound and size return?). So in order to point to, or pass, an assumed-size array to a procedure expecting an assumed or deferred-shape array the user must provide the missing bound information, which can be done by specifying an array section effectively creating an explicit-shape array (see PR94022). So if one has an assumed-size array “arr”, rank 3, and a procedure “sub”, with either an assumed or deferred-shape array dummy argument, one can do: a = arr(:,:,1:n) p => arr(:,:,1:n) call sub(arr(:,:,1:n)) Assuming appropriate declarations of both “a” and “p”. But one can not address the whole assumed-size array: a = arr ! already generates error p=> arr ! already generates error call sub(arr) ! The case here What IMHO might be relevant and that I could find in the standard: 8.5.8.3 Assumed-shape array (par 1): “An assumed-shape array is a nonallocatable nonpointer dummy argument array that takes its shape from its effective argument.” 8.5.8.5 Assumed-size array: C835: “An object whose array bounds are specified by an implied-shape-or-assumed-size-spec shall be a dummy data object or a named constant.” (par. 4): “An assumed-size array shall not appear in a context that requires its shape.” 9.5.2 Whole arrays (par. 2): “An assumed-size array (8.5.8.5) is permitted to appear as a whole array in an executable construct or specification expression only as an actual argument in a procedure reference that does not require the shape.” 10.1.2.2 Primary: C1002 (R1001) The designator shall not be a whole assumed-size array. 10.2.2.2 Syntax of the pointer assignment statement C1025: “The expr shall be a designator that designates a variable with either the TARGET or POINTER attribute and is not an array section with a vector subscript, or it shall be a reference to a function that returns a data pointer.” 15.5.2.4 Ordinary dummy variables (par. 16): “If a dummy argument is an assumed-shape array [...] the actual argument shall not be an assumed-size array.” 15.5.2.7 Pointer dummy variables (par. 2): “If the dummy argument does not have INTENT (IN) [...]. Otherwise, the actual argument shall be a pointer or a valid target for the dummy pointer in a pointer assignment statement. If the actual argument is not a pointer, the dummy pointer becomes pointer associated with the actual argument.” Should the compiler diagnose the error? Well it seems possible to do it and error reports are always better than surprising results... Is it required to? I would believe so... But I am interested on having the compiler hand hold me as much as possible... ;-) Best regards, José Rui
