Hi Paul, your patch looks already very impressive!
Regarding the patch as is, I am still trying to grok it, even with your explanations at hand... While the testcase works as advertised, I noticed that it exhibits a runtime memleak that occurs for (likely) each case where the associate target is an allocatable, class-valued function result. I tried to produce a minimal testcase using class(*), which apparently is not handled by your patch (it ICEs for me): program p implicit none class(*), allocatable :: x(:) x = foo() call prt (x) deallocate (x) ! up to here no memleak... associate (var => foo()) call prt (var) end associate contains function foo() result(res) class(*), allocatable :: res(:) res = [42] end function foo subroutine prt (x) class(*), intent(in) :: x(:) select type (x) type is (integer) print *, x class default stop 99 end select end subroutine prt end Traceback (truncated): foo.f90:9:18: 9 | call prt (var) | 1 internal compiler error: tree check: expected record_type or union_type or qual_union_type, have function_type in gfc_class_len_get, at fortran/trans-expr.cc:271 0x19fd5d5 tree_check_failed(tree_node const*, char const*, int, char const*, ...) ../../gcc-trunk/gcc/tree.cc:8952 0xe1562d tree_check3(tree_node*, char const*, int, char const*, tree_code, tree_code, tree_code) ../../gcc-trunk/gcc/tree.h:3652 0xe3e264 gfc_class_len_get(tree_node*) ../../gcc-trunk/gcc/fortran/trans-expr.cc:271 0xecda48 trans_associate_var ../../gcc-trunk/gcc/fortran/trans-stmt.cc:2325 0xecdd09 gfc_trans_block_construct(gfc_code*) ../../gcc-trunk/gcc/fortran/trans-stmt.cc:2383 [...] I don't see anything wrong with it: NAG groks it, like Nvidia and Flang, while Intel crashes at runtime. Can you have another brief look? Thanks, Harald On 1/6/24 18:26, Paul Richard Thomas wrote:
These PRs come about because of gfortran's single pass parsing. If the function in the title is parsed after the associate construct, then its type and rank are not known. The point at which this becomes a problem is when expressions within the associate block are parsed. primary.cc (gfc_match_varspec) could already deal with intrinsic types and so component references were the trigger for the problem. The two major parts of this patch are the fixup needed in gfc_match_varspec and the resolution of expressions with references in resolve.cc (gfc_fixup_inferred_type_refs). The former relies on the two new functions in symbol.cc to search for derived types with an appropriate component to match the component reference and then set the associate name to have a matching derived type. gfc_fixup_inferred_type_refs is called in resolution and so the type of the selector function is known. gfc_fixup_inferred_type_refs ensures that the component references use this derived type and that array references occur in the right place in expressions and match preceding array specs. Most of the work in preparing the patch was sorting out cases where the selector was not a derived type but, instead, a class function. If it were not for this, the patch would have been submitted six months ago :-( The patch is relatively safe because most of the chunks are guarded by testing for the associate name being an inferred type, which is set in gfc_match_varspec. For this reason, I do not think it likely that the patch will cause regressions. However, it is more than possible that variants not appearing in the submitted testcase will throw up new bugs. Jerry has already given the patch a whirl and found that it applies cleanly, regtests OK and works as advertised. OK for trunk? Paul Fortran: Fix class/derived type function associate selectors [PR87477] 2024-01-06 Paul Thomas <pa...@gcc.gnu.org> gcc/fortran PR fortran/87477 PR fortran/89645 PR fortran/99065 * class.cc (gfc_change_class): New function needed for associate names, when rank changes or a derived type is produced by resolution * dump-parse-tree.cc (show_code_node): Make output for SELECT TYPE more comprehensible. * gfortran.h : Add 'gfc_association_list' to structure 'gfc_association_list'. Add prototypes for 'gfc_find_derived_types', 'gfc_fixup_inferred_type_refs' and 'gfc_change_class'. Add macro IS_INFERRED_TYPE. * match.cc (copy_ts_from_selector_to_associate): Add bolean arg 'select_type' with default false. If this is a select type name and the selector is a inferred type, build the class type and apply it to the associate name. (build_associate_name): Pass true to 'select_type' in call to previous. * parse.cc (parse_associate): If the selector is a inferred type the associate name is too. Make sure that function selector class and rank, if known, are passed to the associate name. If a function result exists, pass its typespec to the associate name. * primary.cc (gfc_match_varspec): If a scalar derived type select type temporary has an array reference, match the array reference, treating this in the same way as an equivalence member. If this is a inferred type with a component reference, call 'gfc_find_derived_types' to find a suitable derived type. * resolve.cc (resolve_variable): Call new function below. (gfc_fixup_inferred_type_refs): New function to ensure that the expression references for a inferred type are consistent with the now fixed up selector. (resolve_assoc_var): Ensure that derived type or class function selectors transmit the correct arrayspec to the associate name. (resolve_select_type): If the selector is an associate name of inferred type and has no component references, the associate name should have its typespec. * symbol.cc (gfc_set_default_type): If an associate name with unknown type has a selector expression, try resolving the expr. (find_derived_types, gfc_find_derived_types): New functions that search for a derived type with a given name. * trans-expr.cc (gfc_conv_variable): Some inferred type exprs escape resolution so call 'gfc_fixup_inferred_type_refs'. * trans-stmt.cc (trans_associate_var): Tidy up expression for 'class_target'. Correctly handle selectors that are class array references, passed as derived types. gcc/testsuite/ PR fortran/87477 PR fortran/89645 PR fortran/99065 * gfortran.dg/associate_64.f90 : New test