[flang]Fix for PR47339

[inderjeet-hcl]

Summary

Issue is raised as PR 47339.
Following test case should generate compile time error for invalid selector at line #4 and #9 :

R1105 selector is expr

or variable

C1103 (R1105) variable shall not be a coindexed object.

[root@localhost flang]# cat -n /root/LLVM/selecttype_coarray.f90

 1	class(*),allocatable :: calc[:]
 2	integer :: icoa[*]
 3	
 4	associate(sel=>icoa[2])
 5	end associate
 6	
 7	icoa = 2
 8	allocate(integer::calc[*])
 9	select type(sel=>calc[2])
10	 type is(integer)
11	  sel = 2
12	end select
13	end

[klausler]

flang/lib/Semantics/resolve-names.cpp

5049

If details.expr() is vacant, so will GetCurrentAssociation().selector.expr be, yes? I think that you can use one or the other. This would be shorter:

if (ExtractCoarrayRef(GetCurrentAssociation().selector.expr)) { // C1103
  Say(...);
}

5054

type is unused

[inderjeet-hcl]

flang/lib/Semantics/resolve-names.cpp

5054

It seems usage of type is not required, I will share updated code.

[inderjeet-hcl]

flang/lib/Semantics/resolve-names.cpp

5049

I agree, I will update code to pass GetCurrentAssociation().selector.expr directly to function ExtractCoarrayRef.
I used additional checks here as similar code was present in function SetTypeFromAssociation(Symbol &symbol). It seems SetTypeFromAssociation needs additional checks as it is getting called from other locations also.

[inderjeet-hcl]

Modified resolve-names.cpp to incorporate review comments. Also, removed comment related to C1103 from tools.cpp.

[DavidTruby]

Is something blocking this change being committed?

[inderjeet-hcl]

@DavidTruby changes were committed on 9th Sep. commit ID is 5ec043e.

[DavidTruby]

Ah ok, can we close this review then? Thanks!

[inderjeet-hcl]

@DavidTruby do I need to take any action to close the review ?

[sameeranjoshi]

Merged
https://reviews.llvm.org/rG5ec043eae1877add1cde2a7bd6e01ef64549a41d

flang/lib/Semantics/resolve-names.cpp

void ConstructVisitor::Post(const parser::EndAssociateStmt &x) {
   PopScope();
   CheckRef(x.v);
 }
 
 void ConstructVisitor::Post(const parser::Association &x) {
   const auto &name{std::get<parser::Name>(x.t)};
   GetCurrentAssociation().name = &name;
   if (auto *symbol{MakeAssocEntity()}) {
+    if (ExtractCoarrayRef(GetCurrentAssociation().selector.expr)) { // C1103
+      Say("Selector must not be a coindexed object"_err_en_US);
+    }
     SetTypeFromAssociation(*symbol);
     SetAttrsFromAssociation(*symbol);
   }
   GetCurrentAssociation() = {}; // clean for further parser::Association.
 }
 
 bool ConstructVisitor::Pre(const parser::ChangeTeamStmt &x) {
   CheckDef(x.t);
   PushScope(Scope::Kind::Block, nullptr);
   PushAssociation();
   return true;
 }
 

 
 void ConstructVisitor::Post(const parser::SelectTypeStmt &x) {
   auto &association{GetCurrentAssociation()};
   if (const std::optional<parser::Name> &name{std::get<1>(x.t)}) {
     // This isn't a name in the current scope, it is in each TypeGuardStmt
     MakePlaceholder(*name, MiscDetails::Kind::SelectTypeAssociateName);
     association.name = &*name;
     auto exprType{association.selector.expr->GetType()};
+    if (ExtractCoarrayRef(association.selector.expr)) { // C1103
+      Say("Selector must not be a coindexed object"_err_en_US);
+    }
     if (exprType && !exprType->IsPolymorphic()) { // C1159
       Say(association.selector.source,
           "Selector '%s' in SELECT TYPE statement must be "
           "polymorphic"_err_en_US);
     }
   } else {
     if (const Symbol *
         whole{UnwrapWholeSymbolDataRef(association.selector.expr)}) {

flang/lib/Semantics/tools.cpp

bool IsOrContainsPolymorphicComponent(const Symbol &symbol) {
   return false;
 }
 
 bool InProtectedContext(const Symbol &symbol, const Scope &currentScope) {
   return IsProtected(symbol) && !IsHostAssociated(symbol, currentScope);
 }
 
 // C1101 and C1158
-// TODO Need to check for a coindexed object (why? C1103?)
 std::optional<parser::MessageFixedText> WhyNotModifiable(
     const Symbol &symbol, const Scope &scope) {
   const Symbol *root{GetAssociationRoot(symbol)};
   if (!root) {
     return "'%s' is construct associated with an expression"_en_US;
   } else if (InProtectedContext(*root, scope)) {
     return "'%s' is protected in this scope"_en_US;
   } else if (IsExternalInPureContext(*root, scope)) {

flang/test/Semantics/resolve95.f90

+! RUN: %S/test_errors.sh %s %t %f18
+! Test SELECT TYPE and ASSOCIATE errors: C1103
+
+subroutine s1()
+  class(*),allocatable :: calc[:]
+  integer,save :: icoa[*]
+  !ERROR: Selector must not be a coindexed object
+  associate(sel=>icoa[2])
+  end associate
+  icoa = 2
+  allocate(integer::calc[*])
+  !ERROR: Selector must not be a coindexed object
+  select type(sel=>calc[2])
+  end select
+end subroutine