fix: variable assignments in if-branches no longer leak into elseif

docs/CHANGELOG.md

@@ -35,6 +35,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- **Variable assignments in `if` branches no longer leak into `elseif` conditions and bodies.** The diagnostic scope cache already records a clean scope snapshot at each `elseif` condition boundary, preventing assignments from preceding `if`/`elseif` bodies from affecting type resolution. Added regression tests to keep it that way. Contributed by @calebdw.
 - **`int<0,max>` no longer triggers a false `type_mismatch_argument` against `non-negative-int`.** Integer range types (`int<min,max>`) are now checked for subtype compatibility with refined-int pseudo-types (`positive-int`, `negative-int`, `non-negative-int`, `non-positive-int`) and vice versa. Range-to-range (`int<1,50>` <: `int<0,100>`) and cross-refined (`positive-int` <: `non-negative-int`) subtyping also work. Contributed by @calebdw.
 - **Resource-to-object migrated handles no longer trigger false argument type errors.** Functions whose handles became objects in PHP 8.1+ (`finfo_open`, `imap_open`, `ftp_connect`, `ldap_connect`, `pg_connect`, `pg_query`, `pspell_new`, and similar) now return the object type matching your configured PHP version instead of the legacy `resource|false`. Passing the handle on to `finfo_file`, `imap_close`, and the like no longer reports a spurious `type_mismatch_argument`. Fixes #164.
 - **External formatters no longer corrupt the connection.** Running `php-cs-fixer` or PHP_CodeSniffer for document formatting could kill the language server: the tool inherited the editor's input channel and consumed bytes meant for the server, dropping the connection and forcing a restart. Formatters now run with their input isolated. A timeout also names the tool that was too slow (`php-cs-fixer timed out after 10000ms`) so the culprit is clear, and the timeout can be raised with `[formatting] timeout` in `.phpantom.toml`. Fixes #149.

src/completion/variable/forward_walk.rs

@@ -5625,6 +5625,12 @@ fn process_if_statement_body<'b>(
             apply_condition_narrowing_inverse(prev_ei.condition, &mut ei_scope, ctx);
             let _ = prev_idx;
         }
+        // Record a scope snapshot at the elseif condition boundary so
+        // that diagnostic variable lookups inside the condition don't
+        // pick up assignments from preceding if/elseif bodies.
+        if is_diagnostic_scope_active() {
+            record_scope_snapshot(ei.condition.span().start.offset, &ei_scope);
+        }
         apply_condition_narrowing(ei.condition, &mut ei_scope, ctx);
         process_condition_assignment(ei.condition, &mut ei_scope, ctx);
         seed_pass_by_ref_in_condition(ei.condition, &mut ei_scope, ctx);
@@ -5639,6 +5645,12 @@ fn process_if_statement_body<'b>(
         for ei in body.else_if_clauses.iter() {
             apply_condition_narrowing_inverse(ei.condition, &mut else_scope, ctx);
         }
+        // Record a scope snapshot at the else boundary so that
+        // diagnostic variable lookups inside the else body don't
+        // pick up assignments from the if/elseif bodies.
+        if is_diagnostic_scope_active() {
+            record_scope_snapshot(else_clause.statement.span().start.offset, &else_scope);
+        }
         walk_body_forward(std::iter::once(else_clause.statement), &mut else_scope, ctx);
         let exits = statement_unconditionally_exits(else_clause.statement);
         (Some(else_scope), exits)
@@ -5825,6 +5837,12 @@ fn process_if_colon_body<'b>(
     let mut all_scopes = vec![then_scope];
     for ei in body.else_if_clauses.iter() {
         let mut ei_scope = pre_if_scope.clone();
+        // Record a scope snapshot at the elseif condition boundary so
+        // that diagnostic variable lookups inside the condition don't
+        // pick up assignments from preceding if/elseif bodies.
+        if is_diagnostic_scope_active() {
+            record_scope_snapshot(ei.condition.span().start.offset, &ei_scope);
+        }
         apply_condition_narrowing(ei.condition, &mut ei_scope, ctx);
         process_condition_assignment(ei.condition, &mut ei_scope, ctx);
         seed_pass_by_ref_in_condition(ei.condition, &mut ei_scope, ctx);
@@ -5834,6 +5852,12 @@ fn process_if_colon_body<'b>(
     if let Some(ref else_clause) = body.else_clause {
         let mut else_scope = pre_if_scope.clone();
         apply_condition_narrowing_inverse(if_stmt.condition, &mut else_scope, ctx);
+        // Record a scope snapshot at the else boundary.
+        if is_diagnostic_scope_active()
+            && let Some(first_stmt) = else_clause.statements.first()
+        {
+            record_scope_snapshot(first_stmt.span().start.offset, &else_scope);
+        }
         walk_body_forward(else_clause.statements.iter(), &mut else_scope, ctx);
         all_scopes.push(else_scope);
     } else {

tests/integration/diagnostics_type_errors.rs

@@ -4681,3 +4681,51 @@ function test(): void {
         type_error_messages(&diags)
     );
 }
+
+// ─── Issue #167: assignment in if-branch must not leak into elseif condition ─
+
+#[test]
+fn no_false_positive_for_var_reassigned_in_if_branch() {
+    let php = r#"<?php
+function normalizeBooleanString(string $value): bool
+{
+    if (mb_strtolower($value) === 't') {
+        $value = true;
+    } elseif (mb_strtolower($value) === 'f') {
+        $value = false;
+    }
+
+    return (bool) $value;
+}
+"#;
+    let diags = collect_with_full_stubs(php);
+    assert!(
+        !has_type_error(&diags),
+        "Assignment in if-branch must not affect elseif condition (issue #167): {:?}",
+        type_error_messages(&diags)
+    );
+}
+
+// ─── Issue #167 (variant): simpler reproduction without stubs ───────────────
+
+#[test]
+fn no_false_positive_for_var_reassigned_in_if_branch_simple() {
+    let php = r#"<?php
+function takes_string(string $s): void {}
+
+function test(string $value): void
+{
+    if ($value === 't') {
+        $value = true;
+    } elseif ($value === 'f') {
+        takes_string($value);
+    }
+}
+"#;
+    let diags = collect(php);
+    assert!(
+        !has_type_error(&diags),
+        "Assignment in if-branch must not leak into elseif (issue #167): {:?}",
+        type_error_messages(&diags)
+    );
+}

tests/integration/diagnostics_unknown_members.rs

@@ -5031,3 +5031,32 @@ class MyController {
         with_diags
     );
 }
+
+// ─── Issue #168: instanceof narrowing must not leak into elseif body ────────
+
+#[test]
+fn no_false_unknown_member_in_elseif_after_instanceof() {
+    let backend = create_test_backend();
+    let uri = "file:///test.php";
+    let php = r#"<?php
+class KnownDateLike {
+    public function format(): string { return 'formatted'; }
+}
+
+function formatDateLike(object $value): string {
+    if ($value instanceof KnownDateLike) {
+        $value = $value->format();
+    } elseif (is_callable([$value, 'getTime'])) {
+        $value = (string) $value->getTime();
+    }
+
+    return (string) $value;
+}
+"#;
+    let diags = unknown_member_diagnostics_with_scope_cache(&backend, uri, php);
+    assert!(
+        diags.is_empty(),
+        "instanceof narrowing from if-branch must not leak into elseif (issue #168): {:?}",
+        diags
+    );
+}