Fix Double-negated instanceof narrowing.

Author: AJenbo

README.md

@@ -75,6 +75,7 @@ PHPantom understands Composer projects out of the box:
 - **[Architecture](docs/ARCHITECTURE.md).** Symbol resolution, stub loading, and inheritance merging.
 - **[Contributing](docs/CONTRIBUTING.md)**
 - **[Changelog](docs/CHANGELOG.md)**
+- **[Benchmarks](https://ajenbo.github.io/phpantom_lsp/dev/bench/).** Completion latency tracked on every commit.
 - **[Roadmap](docs/todo.md).** Planned features and domain-specific plans.
 
 ## Acknowledgements

docs/CHANGELOG.md

@@ -64,6 +64,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - **Hover on variable definition sites.** Hovering a parameter, foreach binding, or catch variable no longer shows a redundant popup when the type is already visible in the signature. Assignment variables still show their resolved type.
 - **Inline `@var` annotations no longer leak across scopes.** A `/** @var Type $var */` annotation in one method no longer affects hover or completion for a same-named variable in a different method or class.
 - **Docblock tag parsing in description text.** Tags like `@throws` appearing mid-sentence in docblock descriptions (e.g. `"filtered out of @throws suggestions."`) are no longer mistakenly parsed as tags. Only `@` at a valid tag position (after the `* ` line prefix) is recognized.
+- **Double-negated `instanceof` narrowing.** `if (!!$x instanceof Foo)` now correctly narrows `$x` to `Foo` inside the block. Previously the double negation was not simplified and the type stayed unresolved.
 
 ## [0.4.0] - 2026-03-01
 

docs/todo/testing.md

@@ -1,11 +1,11 @@
 # PHPantom — Ignored Fixture Tasks
 
-There are **228 fixture tests** in `tests/fixtures/`. Of these, **175
-pass** and **53 are ignored** because they exercise features or bug
+There are **228 fixture tests** in `tests/fixtures/`. Of these, **176
+pass** and **52 are ignored** because they exercise features or bug
 fixes that are not yet implemented. Each ignored fixture has a
 `// ignore:` comment explaining what is missing.
 
-This document groups the 53 ignored fixtures by the underlying work
+This document groups the 52 ignored fixtures by the underlying work
 needed to un-ignore them. Tasks are ordered by the number of fixtures
 they unblock (descending), then by estimated effort. Once a task is
 complete, remove the `// ignore:` line from each fixture, verify the
@@ -338,20 +338,6 @@ clauses.
 
 ---
 
-## 14. Double negated `instanceof` narrowing (1 fixture)
-
-**Ref:** [type-inference.md §23](type-inference.md#23-double-negated-instanceof-narrowing)
-**Impact: Low · Effort: Low**
-
-`if (!!($x instanceof Foo))` does not narrow. The double negation
-should cancel out.
-
-**Fixture:**
-
-- [ ] `narrowing/bangbang_instanceof.fixture` — `!!$x instanceof Foo` narrows inside the block
-
----
-
 ## 15. Negated `@phpstan-assert !Type` (1 fixture)
 
 **Ref:** [type-inference.md §19](type-inference.md#19-negated-phpstan-assert-type)
@@ -546,7 +532,6 @@ Quick wins (Low effort, 1 fixture each):
 
 | Task | Fixture |
 |---|---|
-| §14 Double negated `instanceof` | `narrowing/bangbang_instanceof` |
 | §17 Accessor on new line | `completion/accessor_on_new_line` |
 | §18 Partial static property prefix | `completion/partial_static_property` |
 | §23 `@phpstan-type` in foreach | `type/phpstan_type_alias` |

docs/todo/type-inference.md

@@ -692,17 +692,6 @@ last assertion's narrowing applies.
 
 ---
 
-## 23. Double negated `instanceof` narrowing
-**Impact: Low · Effort: Low**
-
-`if (!!($x instanceof Foo))` and `if (!(!$x instanceof Foo) { return; }`
-do not resolve correctly. The double negation cancels out but the
-narrowing engine does not simplify it.
-
-**Discovered via:** fixture conversion (bangbang_instanceof).
-
----
-
 ## 24. Literal string conditional return type
 **Impact: Low · Effort: Low-Medium**
 

src/completion/types/narrowing.rs

@@ -249,13 +249,11 @@ pub(in crate::completion) fn try_extract_instanceof_with_negation<'b>(
             try_extract_instanceof_with_negation(inner.expression, var_name)
         }
         Expression::UnaryPrefix(prefix) if prefix.operator.is_not() => {
-            // `!expr` — the inner expr should be a (possibly parenthesised) instanceof
-            try_extract_instanceof(prefix.operand, var_name)
-                .map(|cls| (cls, true))
-                .or_else(|| {
-                    // Also support `!is_a($var, ClassName::class)`
-                    try_extract_is_a(prefix.operand, var_name).map(|cls| (cls, true))
-                })
+            // `!expr` — recurse so that `!!expr` (double negation) and
+            // deeper chains like `!!!expr` are handled correctly: each
+            // `!` flips the negation flag.
+            try_extract_instanceof_with_negation(prefix.operand, var_name)
+                .map(|(cls, neg)| (cls, !neg))
         }
         _ => {
             try_extract_instanceof(expr, var_name)

tests/fixtures/narrowing/bangbang_instanceof.fixture

@@ -1,7 +1,7 @@
 // test: double negation with instanceof narrows type
 // feature: completion
 // Adapted from phpactor if-statement/bangbang.test
-// ignore: double negation (!!) with instanceof not resolved
+
 // expect: fooMethod(
 ---
 <?php