[flang] Move check for statement function in BLOCK construct

A BLOCK construct may not contain a statement function definition;
but it may of course contain an assignment statement with an array
element on its left-hand side that looks like a statement function
definition.  These misparsed statement functions are converted
into assignment statements during semantics once it is clear what
they are.  Move the C1107 check for a statement function definition
in a block construct into declaration checking, which is where it
probably should have been in the first place anyway.

Differential Revision: https://reviews.llvm.org/D145112

Author: klausler

flang/lib/Semantics/check-declarations.cpp

@@ -1054,6 +1054,11 @@ void CheckHelper::CheckSubprogram(
             *host);
       }
     }
+    if (GetProgramUnitOrBlockConstructContaining(symbol).kind() ==
+        Scope::Kind::BlockConstruct) { // C1107
+      messages_.Say(symbol.name(),
+          "A statement function definition may not appear in a BLOCK construct"_err_en_US);
+    }
   }
   if (IsElementalProcedure(symbol)) {
     // See comment on the similar check in CheckProcEntity()

flang/lib/Semantics/resolve-names.cpp

@@ -7692,7 +7692,6 @@ void ResolveNamesVisitor::Post(const parser::TypeGuardStmt &x) {
   ConstructVisitor::Post(x);
 }
 bool ResolveNamesVisitor::Pre(const parser::StmtFunctionStmt &x) {
-  CheckNotInBlock("STATEMENT FUNCTION"); // C1107
   if (HandleStmtFunction(x)) {
     return false;
   } else {

flang/test/Semantics/blockconstruct01.f90

@@ -56,11 +56,11 @@ subroutine s6_c1107(x, y)
 end
 
 subroutine s7_c1107
- integer x
+ integer x, arr(1)
  inc(x) = x + 1
   block
-    !ERROR: STATEMENT FUNCTION statement is not allowed in a BLOCK construct
+    !ERROR: A statement function definition may not appear in a BLOCK construct
     dec(x) = x - 1
+    arr(x) = x - 1 ! ok
   end block
 end
-