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

[Pete Steinfeld via Phabricator via llvm-commits]

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Section 10.2.2.4, paragraph 3 states that, for procedure pointer assignment:

  If the pointer object has an explicit interface, its characteristics shall be
  the same as the pointer target ...

Thus, it's illegal for a procedure pointer with an explicit interface to be
associated with a procedure whose interface is implicit.  However, there's no
prohibition that disallows a procedure pointer with an implicit interface from
being associated with a procedure whose interface is explicit.

We were incorrectly emitting an error message for this latter case.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D113706

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
@@ -145,9 +145,7 @@
     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
   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
   end
 
   ! 10.2.2.4(5)
Index: flang/lib/Evaluate/tools.cpp
===================================================================
--- flang/lib/Evaluate/tools.cpp
+++ flang/lib/Evaluate/tools.cpp
@@ -954,12 +954,13 @@
           " 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;
+    // OK
   } else {
     msg = "Procedure %s associated with incompatible procedure"
           " designator '%s'"_err_en_US;


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