[PATCH] D119404: [flang] Allow mixed association of procedure pointers and targets

[Pete Steinfeld via Phabricator via llvm-commits]

PeteSteinfeld updated this revision to Diff 407643.
PeteSteinfeld added a comment.

Responding to Jean's comments.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D119404/new/

https://reviews.llvm.org/D119404

Files:
  flang/lib/Evaluate/tools.cpp
  flang/test/Semantics/assign03.f90
  flang/test/Semantics/associated.f90


Index: flang/test/Semantics/associated.f90
===================================================================
--- flang/test/Semantics/associated.f90
+++ flang/test/Semantics/associated.f90
@@ -59,6 +59,7 @@
     procedure(subrInt) :: subProc
     procedure(subrInt), pointer :: subProcPointer
     procedure(), pointer :: implicitProcPointer
+    procedure(subrCannotBeCalledfromImplicit), pointer :: cannotBeCalledfromImplicitPointer
     logical :: lVar
 
     !ERROR: missing mandatory 'pointer=' argument
@@ -137,10 +138,8 @@
     realProcPointer1 => intProc
     !ERROR: Procedure pointer 'realprocpointer1' associated with incompatible procedure designator 'intproc'
     lvar = associated(realProcPointer1, intProc)
-    !ERROR: Procedure pointer 'subprocpointer' with explicit interface may not be associated with procedure designator 'externalproc' with implicit interface
-    subProcPointer => externalProc
-    !ERROR: Procedure pointer 'subprocpointer' with explicit interface may not be associated with procedure designator 'externalproc' with implicit interface
-    lvar = associated(subProcPointer, externalProc)
+    subProcPointer => externalProc ! OK to associate a procedure pointer  with an explicit interface to a procedure with an implicit interface
+    lvar = associated(subProcPointer, externalProc) ! OK to associate a procedure pointer with an explicit interface to a procedure with an implicit interface
     !ERROR: Subroutine pointer 'subprocpointer' may not be associated with function designator 'intproc'
     subProcPointer => intProc
     !ERROR: Subroutine pointer 'subprocpointer' may not be associated with function designator 'intproc'
@@ -153,5 +152,9 @@
     lvar = associated(implicitProcPointer, subr) ! OK
     !ERROR: Procedure pointer 'implicitprocpointer' with implicit interface may not be associated with procedure designator 'subrcannotbecalledfromimplicit' with explicit interface that cannot be called via an implicit interface
     lvar = associated(implicitProcPointer, subrCannotBeCalledFromImplicit)
+    !ERROR: Procedure pointer 'cannotbecalledfromimplicitpointer' with explicit interface that cannot be called via an implicit interface cannot be associated with procedure designator with an implicit interface
+    cannotBeCalledfromImplicitPointer => externalProc
+    !ERROR: Procedure pointer 'cannotbecalledfromimplicitpointer' with explicit interface that cannot be called via an implicit interface cannot be associated with procedure designator with an implicit interface
+    lvar = associated(cannotBeCalledfromImplicitPointer, externalProc)
   end subroutine test
 end subroutine assoc
Index: flang/test/Semantics/assign03.f90
===================================================================
--- flang/test/Semantics/assign03.f90
+++ flang/test/Semantics/assign03.f90
@@ -176,8 +176,7 @@
     procedure(s), pointer :: p, q
     procedure(), pointer :: r
     external :: s_external
-    !ERROR: Procedure pointer 'p' with explicit interface may not be associated with procedure designator 's_external' with implicit interface
-    p => s_external
+    p => s_external ! OK for a pointer with an explicit interface to be associated with a procedure with an implicit interface
     r => s_module ! OK for a pointer with implicit interface to be associated with a procedure with an explicit interface.  See 10.2.2.4 (3)
   end
 
Index: flang/lib/Evaluate/tools.cpp
===================================================================
--- flang/lib/Evaluate/tools.cpp
+++ flang/lib/Evaluate/tools.cpp
@@ -971,11 +971,18 @@
   } else if (lhsProcedure->HasExplicitInterface() &&
       !rhsProcedure->HasExplicitInterface()) {
     // Section 10.2.2.4, paragraph 3 prohibits associating a procedure pointer
-    // with an explicit interface with a procedure with an implicit interface
-    msg = "Procedure %s with explicit interface may not be associated with"
-          " procedure designator '%s' with implicit interface"_err_en_US;
+    // with an explicit interface with a procedure whose characteristics don't
+    // match.  That's the case if the target procedure has an implicit
+    // interface.  But this case is allowed by several other compilers as long
+    // as the explicit interface can be called via an implicit interface.
+    if (!lhsProcedure->CanBeCalledViaImplicitInterface()) {
+      msg = "Procedure %s with explicit interface that cannot be called via "
+            "an implicit interface cannot be associated with procedure "
+            "designator with an implicit interface"_err_en_US;
+    }
   } else if (!lhsProcedure->HasExplicitInterface() &&
       rhsProcedure->HasExplicitInterface()) {
+    // OK if the target can be called via an implicit interface
     if (!rhsProcedure->CanBeCalledViaImplicitInterface()) {
       msg = "Procedure %s with implicit interface may not be associated "
             "with procedure designator '%s' with explicit interface that "


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