Require type arguments for generic functions in checked scopes. (#589)

We previously added code to allow type arguments to be omitted at some calls to generic function calls.   When type arguments are omitted, void is used as the value for each type argument instead.   We allowed type arguments to be omitted at calls in unchecked scopes and checked bounds_only scopes.  I think the difference in behavior between different forms of checked scopes will likely be confusing, so require type arguments for all checked scopes.

Testing:
- Added tests to the Checked C repo that check this behavior.
- Passed automated testing for Linux.
- Passed local testing for Windows.

Author: dtarditi

lib/Sema/SemaExpr.cpp

@@ -5486,13 +5486,13 @@ ExprResult Sema::ActOnCallExpr(Scope *Scope, Expr *Fn, SourceLocation LParenLoc,
     // where no type arguments have been specified.
     if (Fn->getType()->isItypeGenericFunctionType()) {
        // It is an error in a checked scope.
-      if (GetCheckedScopeInfo() == CSS_BoundsAndTypes) {
+      CheckedScopeSpecifier CSS = GetCheckedScopeInfo();
+      if (CSS == CSS_BoundsAndTypes || CSS == CSS_Bounds) {
         Diag(Fn->getLocEnd(),
               diag::err_expected_type_argument_list_for_itype_generic_call);
         return ExprError();
       }
-      // In an unchecked or checked bounds-only scope,  pass void types
-      // as the type arguments.
+      // In an unchecked scope, pass void types as the type arguments.
       if (DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Fn)) {
         SmallVector<DeclRefExpr::GenericInstInfo::TypeArgument, 4>
            typeArgumentInfos;
@@ -5507,7 +5507,7 @@ ExprResult Sema::ActOnCallExpr(Scope *Scope, Expr *Fn, SourceLocation LParenLoc,
         // a type application node.
         DR->SetGenericInstInfo(Context, typeArgumentInfos);
 
-        // Substitute Type Variables of Function Type in DeclRefExpr
+        // Substitute type arguments into function type in DeclRefExpr
         QualType NewTy =
           SubstituteTypeArgs(DR->getType(), typeArgumentInfos);
         DR->setType(NewTy);