expression_unused_result_unknown diagnostic recognize closures

for any call that is applied to a name i.e. name() the diagnostic will use 'function'
for calls to anonymous functions i.e {...}() the diagnostic will use 'closure'

Author: AnthonyLatsis

include/swift/AST/DiagnosticsSema.def

@@ -2893,7 +2893,7 @@ WARNING(expression_unused_result_call,none,
 WARNING(expression_unused_result_operator,none,
         "result of operator %0 is unused", (DeclName))
 WARNING(expression_unused_result_unknown, none,
-        "result of call to function returning %0 is unused", (Type))
+        "result of call to %select{function|closure}0 returning %1 is unused", (bool, Type))
 WARNING(expression_unused_result, none,
         "expression of type %0 is unused", (Type))
 WARNING(expression_unused_init_result,none,

lib/Sema/TypeCheckStmt.cpp

@@ -1322,9 +1322,9 @@ void TypeChecker::checkIgnoredExpr(Expr *E) {
         .highlight(SR1).highlight(SR2);
     } else
       diagnose(fn->getLoc(), diag::expression_unused_result_unknown,
-               valueE->getType())
+               isa<ClosureExpr>(fn), valueE->getType())
         .highlight(SR1).highlight(SR2);
-
+      
     return;
   }