[PATCH] D113706: [flang] Allow implicit procedure pointers to associate with explicit procedures

[Pete Steinfeld via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG4f11944652de: [flang] Allow implicit procedure pointers to associate with explicit procedures (authored by PeteSteinfeld).

Changed prior to commit:
  https://reviews.llvm.org/D113706?vs=386848&id=387303#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D113706/new/

https://reviews.llvm.org/D113706

Files:
  flang/lib/Evaluate/characteristics.cpp
  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
@@ -36,6 +36,10 @@
     integer :: i
   end subroutine subr
 
+  subroutine subrCannotBeCalledfromImplicit(i)
+    integer :: i(:)
+  end subroutine subrCannotBeCalledfromImplicit
+
   subroutine test()
     integer :: intVar
     integer, target :: targetIntVar1
@@ -145,9 +149,9 @@
     intProcPointer1 => subProc
     !ERROR: Function pointer 'intprocpointer1' may not be associated with subroutine designator 'subproc'
     lvar = associated(intProcPointer1, subProc)
-    !ERROR: Procedure pointer 'implicitprocpointer' with implicit interface may not be associated with procedure designator 'subr' with explicit interface
-    implicitProcPointer => subr
-    !ERROR: Procedure pointer 'implicitprocpointer' with implicit interface may not be associated with procedure designator 'subr' with explicit interface
-    lvar = associated(implicitProcPointer, subr)
+    implicitProcPointer => subr ! OK for an implicit point to point to an explicit proc
+    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)
   end subroutine test
 end subroutine assoc
Index: flang/test/Semantics/assign03.f90
===================================================================
--- flang/test/Semantics/assign03.f90
+++ flang/test/Semantics/assign03.f90
@@ -178,8 +178,7 @@
     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
-    !ERROR: Procedure pointer 'r' with implicit interface may not be associated with procedure designator 's_module' with explicit interface
-    r => s_module
+    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
 
   ! 10.2.2.4(5)
Index: flang/lib/Evaluate/tools.cpp
===================================================================
--- flang/lib/Evaluate/tools.cpp
+++ flang/lib/Evaluate/tools.cpp
@@ -954,12 +954,17 @@
           " designator '%s'"_err_en_US;
   } 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;
   } else if (!lhsProcedure->HasExplicitInterface() &&
       rhsProcedure->HasExplicitInterface()) {
-    msg = "Procedure %s with implicit interface may not be associated with"
-          " procedure designator '%s' with explicit interface"_err_en_US;
+    if (!rhsProcedure->CanBeCalledViaImplicitInterface()) {
+      msg = "Procedure %s with implicit interface may not be associated "
+            "with procedure designator '%s' with explicit interface that "
+            "cannot be called via an implicit interface"_err_en_US;
+    }
   } else {
     msg = "Procedure %s associated with incompatible procedure"
           " designator '%s'"_err_en_US;
Index: flang/lib/Evaluate/characteristics.cpp
===================================================================
--- flang/lib/Evaluate/characteristics.cpp
+++ flang/lib/Evaluate/characteristics.cpp
@@ -833,6 +833,7 @@
 }
 
 bool Procedure::CanBeCalledViaImplicitInterface() const {
+  // TODO: Pass back information on why we return false
   if (attrs.test(Attr::Elemental) || attrs.test(Attr::BindC)) {
     return false; // 15.4.2.2(5,6)
   } else if (IsFunction() &&


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