Unified: Handle Swift default with an ignore pattern

unified/extractor/ast_types.yml

@@ -387,10 +387,10 @@ named:
 
   # A single `case ...:` (or `default:`) entry in a switch.
   # An entry with multiple `case p1, p2:` patterns uses an `or_pattern`.
-  # A `default:` entry has no pattern.
+  # A `default:` entry uses an `ignore_pattern`.
   switch_case:
     modifier*: modifier
-    pattern?: expr
+    pattern: expr
     body: block
 
   # Evaluate 'expr' and match its result against 'pattern', and return true if it matches.

unified/extractor/src/languages/swift/swift.rs

@@ -918,7 +918,7 @@ fn translation_rules() -> Vec<Rule<SwiftContext>> {
         ),
         // A `switch` statement. Each `switchCase` becomes a `switch_case` with a
         // pattern (or an `or_pattern` for comma-separated `case a, b:`) and a
-        // body; a `default:` case has a body but no pattern. The case items and
+        // body; a `default:` case uses an `ignore_pattern`. The case items and
         // body are auto-translated; the Rust block only picks the pattern shape
         // by arity (the query engine can't branch on list length).
         rule!(
@@ -934,9 +934,11 @@ fn translation_rules() -> Vec<Rule<SwiftContext>> {
                 body: (block stmt: {body}))
         ),
         rule!(
-            (switchCase label: (switchDefaultLabel) statements: _* @body)
+            (switchCase label: (switchDefaultLabel defaultKeyword: @@keyword) statements: _* @body)
             =>
-            (switch_case body: (block stmt: {body}))
+            (switch_case
+                pattern: (ignore_pattern #{keyword})
+                body: (block stmt: {body}))
         ),
         // A single case item unwraps to its pattern, possibly boxed in conditional_pattern
         rule!(

unified/extractor/tests/corpus/swift/control-flow/binding-modifier-does-not-leak-to-sibling.output

@@ -105,7 +105,8 @@ top_level source="⟨body⟩"
                       argument:
                         argument source="⟨value⟩"
                           value: string_literal "\"matched\"" source="\"matched\""
-            switch_case source="default:\n  ⟨body⟩"
+            switch_case source="⟨pattern⟩:\n  ⟨body⟩"
+              pattern: ignore_pattern "default" source="default"
               body:
                 block source="⟨stmt⟩"
                   stmt: break_expr "break" source="break"

unified/extractor/tests/corpus/swift/control-flow/fallthrough.output

@@ -104,7 +104,8 @@ top_level source="⟨body⟩"
                       body:
                         block source="⟨stmt⟩"
                           stmt: unsupported_node "fallthrough" source="fallthrough"
-                    switch_case source="default:\n    ⟨body⟩"
+                    switch_case source="⟨pattern⟩:\n    ⟨body⟩"
+                      pattern: ignore_pattern "default" source="default"
                       body:
                         block source="⟨stmt⟩"
                           stmt: break_expr "break" source="break"

unified/extractor/tests/corpus/swift/control-flow/nested-enum-case-pattern.output

@@ -286,7 +286,8 @@ top_level source="⟨body⟩"
               body:
                 block source="⟨stmt⟩"
                   stmt: break_expr "break" source="break"
-            switch_case source="default:\n  ⟨body⟩"
+            switch_case source="⟨pattern⟩:\n  ⟨body⟩"
+              pattern: ignore_pattern "default" source="default"
               body:
                 block source="⟨stmt⟩"
                   stmt: break_expr "break" source="break"

unified/extractor/tests/corpus/swift/control-flow/switch-case-item-where-clauses.output

@@ -200,7 +200,8 @@ top_level source="⟨body⟩"
                       argument:
                         argument source="⟨value⟩"
                           value: string_literal "\"non-positive\"" source="\"non-positive\""
-            switch_case source="default:\n  ⟨body⟩"
+            switch_case source="⟨pattern⟩:\n  ⟨body⟩"
+              pattern: ignore_pattern "default" source="default"
               body:
                 block source="⟨stmt⟩"
                   stmt:

unified/extractor/tests/corpus/swift/control-flow/switch-expression-pattern.output

@@ -393,7 +393,8 @@ top_level source="⟨body⟩"
                       argument:
                         argument source="⟨value⟩"
                           value: identifier "fallback" source="fallback"
-            switch_case source="default:\n    ⟨body⟩"
+            switch_case source="⟨pattern⟩:\n    ⟨body⟩"
+              pattern: ignore_pattern "default" source="default"
               body:
                 block source="⟨stmt⟩"
                   stmt: break_expr "break" source="break"

unified/extractor/tests/corpus/swift/control-flow/switch-statement.output

@@ -151,7 +151,8 @@ top_level source="⟨body⟩"
                       argument:
                         argument source="⟨value⟩"
                           value: string_literal "\"two or three\"" source="\"two or three\""
-            switch_case source="default:\n  ⟨body⟩"
+            switch_case source="⟨pattern⟩:\n  ⟨body⟩"
+              pattern: ignore_pattern "default" source="default"
               body:
                 block source="⟨stmt⟩"
                   stmt:

unified/extractor/tests/corpus/swift/types/binding-modifier-does-not-leak-into-accessor-body.output

@@ -114,7 +114,8 @@ top_level source="var p: Int {\n  ⟨body⟩\n}"
                           stmt:
                             return_expr source="return ⟨value⟩"
                               value: int_literal "1" source="1"
-                    switch_case source="default:\n      ⟨body⟩"
+                    switch_case source="⟨pattern⟩:\n      ⟨body⟩"
+                      pattern: ignore_pattern "default" source="default"
                       body:
                         block source="⟨stmt⟩"
                           stmt:

unified/extractor/tests/corpus/swift/variables/binding-modifier-does-not-leak-into-initializer.output

@@ -77,7 +77,8 @@ top_level source="⟨body⟩"
                   body:
                     block source="⟨stmt⟩"
                       stmt: int_literal "1" source="1"
-                switch_case source="default: ⟨body⟩"
+                switch_case source="⟨pattern⟩: ⟨body⟩"
+                  pattern: ignore_pattern "default" source="default"
                   body:
                     block source="⟨stmt⟩"
                       stmt: int_literal "2" source="2"

unified/extractor/tests/location_tests.rs

@@ -104,6 +104,15 @@ fn synthesized_condition_and_switch_nodes_use_child_ranges() {
     assert_has_span(&ast, source, "block", None, "c");
 }
 
+#[test]
+fn switch_default_patterns_span_the_default_keyword() {
+    let source = "switch x { case _: break; @unknown default: break }";
+    let ast = desugar(source);
+
+    assert_has_span(&ast, source, "ignore_pattern", Some("_"), "_");
+    assert_has_span(&ast, source, "ignore_pattern", Some("default"), "default");
+}
+
 #[test]
 fn declaration_and_operator_tokens_keep_precise_ranges() {
     let source = "func f() { return x }\nlet y = try? await value! as? T\nlet z = value is T";

unified/ql/lib/codeql/unified/internal/Ast.qll

@@ -1278,7 +1278,7 @@ module Unified {
     final override string getAPrimaryQlClass() { result = "SwitchCase" }
 
     /** Gets the node corresponding to the field `body`. */
-    final F::Block getBody() { unified_switch_case_def(this, result) }
+    final F::Block getBody() { unified_switch_case_def(this, result, _) }
 
     /** Gets the node corresponding to the field `modifier`. */
     final F::Modifier getModifier(int i) { unified_switch_case_modifier(this, i, result) }
@@ -1287,13 +1287,13 @@ module Unified {
     final F::Modifier getAModifier() { result = this.getModifier(_) }
 
     /** Gets the node corresponding to the field `pattern`. */
-    final F::Expr getPattern() { unified_switch_case_pattern(this, result) }
+    final F::Expr getPattern() { unified_switch_case_def(this, _, result) }
 
     /** Gets a field or child node of this node. */
     final override F::AstNode getAFieldOrChild() {
-      unified_switch_case_def(this, result) or
+      unified_switch_case_def(this, result, _) or
       unified_switch_case_modifier(this, _, result) or
-      unified_switch_case_pattern(this, result)
+      unified_switch_case_def(this, _, result)
     }
   }
 

unified/ql/lib/codeql/unified/internal/ControlFlowGraph.qll

@@ -247,7 +247,7 @@ module Ast implements AstSig<Location> {
   }
 
   class DefaultCase extends Case {
-    DefaultCase() { not exists(super.getPattern()) }
+    DefaultCase() { super.getPattern() instanceof U::IgnorePattern }
   }
 
   class ConditionalExpr = U::IfExpr;

unified/ql/lib/unified.dbscheme

@@ -809,14 +809,10 @@ unified_switch_case_modifier(
   unique int modifier: @unified_token_modifier ref
 );
 
-unified_switch_case_pattern(
-  unique int unified_switch_case: @unified_switch_case ref,
-  unique int pattern: @unified_expr ref
-);
-
 unified_switch_case_def(
   unique int id: @unified_switch_case,
-  int body: @unified_block ref
+  int body: @unified_block ref,
+  int pattern: @unified_expr ref
 );
 
 #keyset[unified_switch_expr, index]

unified/ql/test/library-tests/controlflow/basicblock-slices.expected

@@ -132,7 +132,7 @@
 | 155 | cfg.swift:155:5:157:17 | SwitchCase | 'SwitchCase -V 42' |
 | 156 | cfg.swift:156:7:157:17 | Block | 'Block -V print -> Argument -V "42!" -^ print(...)' |
 | 157 | cfg.swift:157:7:157:17 |  | '' |
-| 158 | cfg.swift:158:5:159:34 | SwitchCase | 'SwitchCase' |
+| 158 | cfg.swift:158:5:159:34 | SwitchCase | 'SwitchCase -V default' |
 | 159 | cfg.swift:159:7:159:34 | Block | 'Block -V IfExpr -V x -> 10 -^ ... > ...' |
 | 159 | cfg.swift:159:19:159:34 | Block | 'Block -V false -^ ReturnExpr' |
 | 162 | cfg.swift:162:3:162:31 | var obj | 'var obj -V obj -> AnyObject -> C -> Argument -V x -^ C(...)' |
@@ -482,7 +482,7 @@
 | 595 | cfg.swift:595:3:598:3 | let a | 'let a -V a -> SwitchExpr -V x' |
 | 596 | cfg.swift:596:5:596:17 | SwitchCase | 'SwitchCase -V 0 -> 5 -^ ... ..< ...' |
 | 596 | cfg.swift:596:17:596:17 | Block | 'Block -V 1' |
-| 597 | cfg.swift:597:5:597:14 | SwitchCase | 'SwitchCase -V Block -V 2' |
+| 597 | cfg.swift:597:5:597:14 | SwitchCase | 'SwitchCase -V default -> Block -V 2' |
 | 599 | cfg.swift:599:3:601:18 | let b | 'let b -V b' |
 | 600 | cfg.swift:600:9:601:18 | IfExpr | 'IfExpr -V x -> 42 -^ ... < ...' |
 | 600 | cfg.swift:600:21:600:25 | Block | 'Block -V 1' |