fix(semantic): TSConditionalType scope enter/exit locations (#6351)

Fixes the same problem as #6270, but uses `#[scope(enter_before)]` and `#[scope(exit_after)]` to correct scope entry/exit locations.

crates/oxc_ast/src/ast/ts.rs

@@ -347,10 +347,12 @@ pub struct TSConditionalType<'a> {
     /// The type before `extends` in the test expression.
     pub check_type: TSType<'a>,
     /// The type `check_type` is being tested against.
+    #[scope(enter_before)]
     pub extends_type: TSType<'a>,
     /// The type evaluated to if the test is true.
     pub true_type: TSType<'a>,
     /// The type evaluated to if the test is false.
+    #[scope(exit_before)]
     pub false_type: TSType<'a>,
     #[serde(skip)]
     #[clone_in(default)]

crates/oxc_ast/src/generated/visit.rs

@@ -1913,12 +1913,12 @@ pub mod walk {
     pub fn walk_ts_conditional_type<'a, V: Visit<'a>>(visitor: &mut V, it: &TSConditionalType<'a>) {
         let kind = AstKind::TSConditionalType(visitor.alloc(it));
         visitor.enter_node(kind);
-        visitor.enter_scope(ScopeFlags::empty(), &it.scope_id);
         visitor.visit_ts_type(&it.check_type);
+        visitor.enter_scope(ScopeFlags::empty(), &it.scope_id);
         visitor.visit_ts_type(&it.extends_type);
         visitor.visit_ts_type(&it.true_type);
-        visitor.visit_ts_type(&it.false_type);
         visitor.leave_scope();
+        visitor.visit_ts_type(&it.false_type);
         visitor.leave_node(kind);
     }
 

crates/oxc_ast/src/generated/visit_mut.rs

@@ -1956,12 +1956,12 @@ pub mod walk_mut {
     ) {
         let kind = AstType::TSConditionalType;
         visitor.enter_node(kind);
-        visitor.enter_scope(ScopeFlags::empty(), &it.scope_id);
         visitor.visit_ts_type(&mut it.check_type);
+        visitor.enter_scope(ScopeFlags::empty(), &it.scope_id);
         visitor.visit_ts_type(&mut it.extends_type);
         visitor.visit_ts_type(&mut it.true_type);
-        visitor.visit_ts_type(&mut it.false_type);
         visitor.leave_scope();
+        visitor.visit_ts_type(&mut it.false_type);
         visitor.leave_node(kind);
     }
 

crates/oxc_semantic/tests/fixtures/typescript-eslint/type-declaration/conditional-nested.snap

@@ -12,30 +12,7 @@ SCOPES
       {
         "children": [
           {
-            "children": [
-              {
-                "children": [],
-                "flags": "ScopeFlags(StrictMode)",
-                "id": 3,
-                "node": "TSConditionalType",
-                "symbols": [
-                  {
-                    "flags": "SymbolFlags(TypeParameter)",
-                    "id": 3,
-                    "name": "U",
-                    "node": "TSTypeParameter(U)",
-                    "references": [
-                      {
-                        "flags": "ReferenceFlags(Type)",
-                        "id": 5,
-                        "name": "U",
-                        "node_id": 33
-                      }
-                    ]
-                  }
-                ]
-              }
-            ],
+            "children": [],
             "flags": "ScopeFlags(StrictMode)",
             "id": 2,
             "node": "TSConditionalType",
@@ -55,6 +32,28 @@ SCOPES
                 ]
               }
             ]
+          },
+          {
+            "children": [],
+            "flags": "ScopeFlags(StrictMode)",
+            "id": 3,
+            "node": "TSConditionalType",
+            "symbols": [
+              {
+                "flags": "SymbolFlags(TypeParameter)",
+                "id": 3,
+                "name": "U",
+                "node": "TSTypeParameter(U)",
+                "references": [
+                  {
+                    "flags": "ReferenceFlags(Type)",
+                    "id": 5,
+                    "name": "U",
+                    "node_id": 33
+                  }
+                ]
+              }
+            ]
           }
         ],
         "flags": "ScopeFlags(StrictMode)",

crates/oxc_semantic/tests/integration/scopes.rs

@@ -239,3 +239,25 @@ fn get_child_ids() {
     let child_scope_ids = scopes.get_child_ids(child_scope_ids[0]);
     assert!(child_scope_ids.is_empty());
 }
+
+#[test]
+fn test_ts_conditional_types() {
+    SemanticTester::ts("type A<T> = T extends string ? T : false;")
+        .has_some_symbol("T")
+        .has_number_of_references(2)
+        .test();
+
+    // Conditional types create a new scope after check_type.
+    SemanticTester::ts(
+        "type S<A> = A extends (infer B extends number ? string : never) ? B : false;",
+    )
+    .has_some_symbol("B")
+    .has_number_of_references(1)
+    .test();
+
+    // Inferred type parameter is only available within true branch
+    SemanticTester::ts("type S<A> = A extends infer R ? never : R")
+        .has_some_symbol("R")
+        .has_number_of_references(0)
+        .test();
+}

crates/oxc_traverse/src/generated/walk.rs

@@ -3964,13 +3964,6 @@ pub(crate) unsafe fn walk_ts_conditional_type<'a, Tr: Traverse<'a>>(
     ctx: &mut TraverseCtx<'a>,
 ) {
     traverser.enter_ts_conditional_type(&mut *node, ctx);
-    let previous_scope_id = ctx.current_scope_id();
-    ctx.set_current_scope_id(
-        (*((node as *mut u8).add(ancestor::OFFSET_TS_CONDITIONAL_TYPE_SCOPE_ID)
-            as *mut Cell<Option<ScopeId>>))
-            .get()
-            .unwrap(),
-    );
     let pop_token = ctx.push_stack(Ancestor::TSConditionalTypeCheckType(
         ancestor::TSConditionalTypeWithoutCheckType(node, PhantomData),
     ));
@@ -3979,6 +3972,13 @@ pub(crate) unsafe fn walk_ts_conditional_type<'a, Tr: Traverse<'a>>(
         (node as *mut u8).add(ancestor::OFFSET_TS_CONDITIONAL_TYPE_CHECK_TYPE) as *mut TSType,
         ctx,
     );
+    let previous_scope_id = ctx.current_scope_id();
+    ctx.set_current_scope_id(
+        (*((node as *mut u8).add(ancestor::OFFSET_TS_CONDITIONAL_TYPE_SCOPE_ID)
+            as *mut Cell<Option<ScopeId>>))
+            .get()
+            .unwrap(),
+    );
     ctx.retag_stack(AncestorType::TSConditionalTypeExtendsType);
     walk_ts_type(
         traverser,
@@ -3991,6 +3991,7 @@ pub(crate) unsafe fn walk_ts_conditional_type<'a, Tr: Traverse<'a>>(
         (node as *mut u8).add(ancestor::OFFSET_TS_CONDITIONAL_TYPE_TRUE_TYPE) as *mut TSType,
         ctx,
     );
+    ctx.set_current_scope_id(previous_scope_id);
     ctx.retag_stack(AncestorType::TSConditionalTypeFalseType);
     walk_ts_type(
         traverser,
@@ -3998,7 +3999,6 @@ pub(crate) unsafe fn walk_ts_conditional_type<'a, Tr: Traverse<'a>>(
         ctx,
     );
     ctx.pop_stack(pop_token);
-    ctx.set_current_scope_id(previous_scope_id);
     traverser.exit_ts_conditional_type(&mut *node, ctx);
 }
 

tasks/coverage/snapshots/semantic_typescript.snap

@@ -3897,13 +3897,13 @@ Bindings mismatch:
 after transform: ScopeId(2): ["P", "attrs"]
 rebuilt        : ScopeId(1): ["attrs"]
 Scope children mismatch:
-after transform: ScopeId(2): [ScopeId(3)]
+after transform: ScopeId(2): [ScopeId(3), ScopeId(5)]
 rebuilt        : ScopeId(1): []
 Bindings mismatch:
 after transform: ScopeId(6): ["P", "attrs"]
 rebuilt        : ScopeId(2): ["attrs"]
 Scope children mismatch:
-after transform: ScopeId(6): [ScopeId(7)]
+after transform: ScopeId(6): [ScopeId(7), ScopeId(8)]
 rebuilt        : ScopeId(2): []
 Bindings mismatch:
 after transform: ScopeId(9): ["P", "attrs"]
@@ -8852,7 +8852,7 @@ Bindings mismatch:
 after transform: ScopeId(3): ["D", "clientDef"]
 rebuilt        : ScopeId(1): ["clientDef"]
 Scope children mismatch:
-after transform: ScopeId(3): [ScopeId(4)]
+after transform: ScopeId(3): [ScopeId(4), ScopeId(5)]
 rebuilt        : ScopeId(1): []
 Unresolved references mismatch:
 after transform: ["Record"]
@@ -17164,7 +17164,7 @@ Scope children mismatch:
 after transform: ScopeId(8): [ScopeId(9), ScopeId(10)]
 rebuilt        : ScopeId(2): []
 Symbol reference IDs mismatch for "state":
-after transform: SymbolId(8): [ReferenceId(11), ReferenceId(12), ReferenceId(13), ReferenceId(15)]
+after transform: SymbolId(9): [ReferenceId(11), ReferenceId(12), ReferenceId(13), ReferenceId(15)]
 rebuilt        : SymbolId(1): [ReferenceId(0), ReferenceId(1), ReferenceId(2)]
 Unresolved references mismatch:
 after transform: ["State", "true"]
@@ -52205,10 +52205,10 @@ Scope children mismatch:
 after transform: ScopeId(0): [ScopeId(1), ScopeId(4), ScopeId(5), ScopeId(6), ScopeId(7), ScopeId(10), ScopeId(11), ScopeId(12), ScopeId(13), ScopeId(16), ScopeId(17), ScopeId(18), ScopeId(19), ScopeId(22), ScopeId(23), ScopeId(24), ScopeId(25), ScopeId(28), ScopeId(29), ScopeId(30), ScopeId(31), ScopeId(34), ScopeId(35), ScopeId(36), ScopeId(37), ScopeId(40), ScopeId(41), ScopeId(42), ScopeId(43), ScopeId(44), ScopeId(47), ScopeId(48), ScopeId(49), ScopeId(50), ScopeId(51), ScopeId(54), ScopeId(55), ScopeId(56), ScopeId(57), ScopeId(58), ScopeId(61), ScopeId(63), ScopeId(64), ScopeId(67), ScopeId(69), ScopeId(71), ScopeId(73), ScopeId(77), ScopeId(80), ScopeId(84), ScopeId(87), ScopeId(89), ScopeId(90), ScopeId(91), ScopeId(92), ScopeId(95), ScopeId(96), ScopeId(98), ScopeId(99), ScopeId(100), ScopeId(101), ScopeId(102), ScopeId(103), ScopeId(107), ScopeId(108), ScopeId(109), ScopeId(110), ScopeId(111)]
 rebuilt        : ScopeId(0): [ScopeId(1), ScopeId(2)]
 Reference symbol mismatch for "x1":
-after transform: SymbolId(126) "x1"
+after transform: SymbolId(127) "x1"
 rebuilt        : <None>
 Reference symbol mismatch for "x2":
-after transform: SymbolId(132) "x2"
+after transform: SymbolId(133) "x2"
 rebuilt        : <None>
 Unresolved references mismatch:
 after transform: ["Promise"]