[Diag] Move invalid where clause on top-level decl diagnostic to Sema

Author: AnthonyLatsis

include/swift/AST/DiagnosticsParse.def

@@ -1658,9 +1658,6 @@ ERROR(redundant_class_requirement,none,
       "redundant 'class' requirement", ())
 ERROR(late_class_requirement,none,
       "'class' must come first in the requirement list", ())
-ERROR(where_toplevel_nongeneric,none,
-      "'where' clause cannot be attached to non-generic "
-      "top-level declaration", ())
 ERROR(where_inside_brackets,none,
         "'where' clause next to generic parameters is obsolete, "
         "must be written following the declaration's type", ())

include/swift/AST/DiagnosticsSema.def

@@ -1575,7 +1575,7 @@ NOTE(unstable_mangled_name_add_objc,none,
      "for compatibility with existing archives, use '@objc' "
      "to record the Swift 3 runtime name", ())
 
-// Generic types
+// Generic declarations
 ERROR(unsupported_type_nested_in_generic_function,none,
       "type %0 cannot be nested in generic function %1",
       (Identifier, DeclName))
@@ -1591,6 +1591,12 @@ ERROR(unsupported_type_nested_in_protocol_extension,none,
 ERROR(unsupported_nested_protocol,none,
       "protocol %0 cannot be nested inside another declaration",
       (Identifier))
+ERROR(where_nongeneric_ctx,none,
+      "'where' clause on non-generic member declaration requires a "
+      "generic context", ())
+ERROR(where_nongeneric_toplevel,none,
+      "'where' clause cannot be applied to a non-generic top-level "
+      "declaration", ())
 
 // Type aliases
 ERROR(type_alias_underlying_type_access,none,
@@ -2755,10 +2761,6 @@ ERROR(dynamic_self_stored_property_init,none,
 ERROR(dynamic_self_default_arg,none,
       "covariant 'Self' type cannot be referenced from a default argument expression", ())
 
-ERROR(where_nongeneric_ctx,none,
-      "'where' clause on non-generic member declaration requires a "
-      "generic context", ())
-
 //------------------------------------------------------------------------------
 // MARK: Type Check Attributes
 //------------------------------------------------------------------------------

lib/Parse/ParseGeneric.cpp

@@ -418,12 +418,10 @@ parseFreestandingGenericWhereClause(GenericContext *genCtx,
 
     genericParams->addTrailingWhereClause(Context, WhereLoc, Requirements);
 
-  // A where clause that references only outer generic parameters?
-  } else if (flags.contains(PD_HasContainerType)) {
+  } else {
+    // A where clause against outer generic parameters.
     genCtx->setTrailingWhereClause(
         TrailingWhereClause::create(Context, WhereLoc, Requirements));
-  } else {
-    diagnose(WhereLoc, diag::where_toplevel_nongeneric);
   }
 
   return ParserStatus();

lib/Sema/TypeCheckGeneric.cpp

@@ -620,11 +620,15 @@ GenericSignatureRequest::evaluate(Evaluator &evaluator,
       return cast<SubscriptDecl>(accessor->getStorage())->getGenericSignature();
     }
 
-  // ...or we may have a where clause dependent on outer generic parameters.
+  // ...or we may only have a contextual where clause.
   } else if (const auto *where = GC->getTrailingWhereClause()) {
     // If there is no generic context for the where clause to
     // rely on, diagnose that now and bail out.
-    if (!GC->isGenericContext()) {
+    if (GC->getParent()->isModuleScopeContext()) {
+      GC->getASTContext().Diags.diagnose(where->getWhereLoc(),
+                                         diag::where_nongeneric_toplevel);
+      return nullptr;
+    } else if (!GC->isGenericContext()) {
       GC->getASTContext().Diags.diagnose(where->getWhereLoc(),
                                          diag::where_nongeneric_ctx);
       return nullptr;

test/Generics/invalid.swift

@@ -1,17 +1,5 @@
 // RUN: %target-typecheck-verify-swift
 
-func bet() where A : B {} // expected-error {{'where' clause cannot be attached to non-generic top-level declaration}}
-
-typealias gimel = Int where A : B // expected-error {{'where' clause cannot be attached to non-generic top-level declaration}}
-
-class dalet where A : B {} // expected-error {{'where' clause cannot be attached to non-generic top-level declaration}}
-
-struct Where {
-  func bet() where A == B {}  // expected-error {{'where' clause on non-generic member declaration requires a generic context}}
-  typealias gimel = Int where A : B  // expected-error {{'where' clause on non-generic member declaration requires a generic context}}
-  class dalet where A : B {}  // expected-error {{'where' clause on non-generic member declaration requires a generic context}}
-}
-
 protocol he where A : B { // expected-error {{use of undeclared type 'A'}}
   // expected-error@-1 {{use of undeclared type 'B'}}
 

test/Generics/where_clause_contextually_generic_decls.swift

@@ -1,5 +1,17 @@
 // RUN: %target-typecheck-verify-swift -typecheck %s -verify -swift-version 4
 
+func bet() where A : B {} // expected-error {{'where' clause cannot be applied to a non-generic top-level declaration}}
+
+typealias gimel = Int where A : B // expected-error {{'where' clause cannot be applied to a non-generic top-level declaration}}
+
+class dalet where A : B {} // expected-error {{'where' clause cannot be applied to a non-generic top-level declaration}}
+
+struct Where {
+  func bet() where A == B {}  // expected-error {{'where' clause on non-generic member declaration requires a generic context}}
+  typealias gimel = Int where A : B  // expected-error {{'where' clause on non-generic member declaration requires a generic context}}
+  class dalet where A : B {}  // expected-error {{'where' clause on non-generic member declaration requires a generic context}}
+}
+
 // Make sure Self: ... is correctly diagnosed in classes
 
 class SelfInGenericClass<T> {