feat: Improve control flow handling

crates/stc_ts_file_analyzer/src/analyzer/stmt/loops.rs

@@ -27,12 +27,20 @@ enum ForHeadKind {
     Of { is_awaited: bool },
 }
 
+#[derive(Debug, Clone, Copy)]
+enum LoopKind {
+    While,
+    DoWhile,
+    ForIn,
+    ForOf { is_awaited: bool },
+}
+
 impl Analyzer<'_, '_> {
     /// We evaluate loop bodies multiple time.
     /// But actually we don't report errors
     ///
     /// If type does not change due to a loop, we evaluate
-    fn validate_loop_body_with_scope(&mut self, test: Option<&RExpr>, body: &RStmt) -> VResult<()> {
+    fn validate_loop_body_with_scope(&mut self, test: Option<&RExpr>, body: &RStmt, kind: LoopKind) -> VResult<()> {
         let mut orig_facts = self.cur_facts.take();
 
         let mut prev_facts = orig_facts.true_facts.take();
@@ -42,10 +50,8 @@ impl Analyzer<'_, '_> {
         let mut orig_vars = Some(self.scope.vars.clone());
 
         loop {
-            let mut facts_from_body: CondFacts = self.with_child_with_hook(
-                ScopeKind::LoopBody { last },
-                prev_facts.clone(),
-                |child: &mut Analyzer| {
+            let facts_from_cond: CondFacts =
+                self.with_child(ScopeKind::LoopBody { last }, prev_facts.clone(), |child: &mut Analyzer| {
                     child.ctx.ignore_errors |= !last;
 
                     {
@@ -56,6 +62,18 @@ impl Analyzer<'_, '_> {
                         test.visit_with(&mut *child.with_ctx(ctx));
                     }
 
+                    Ok(child.cur_facts.true_facts.take())
+                })?;
+
+            let mut facts_for_body = prev_facts.clone();
+            facts_for_body += facts_from_cond.clone();
+
+            let mut facts_from_body: CondFacts = self.with_child_with_hook(
+                ScopeKind::LoopBody { last },
+                facts_from_cond.clone(),
+                |child: &mut Analyzer| {
+                    child.ctx.ignore_errors |= !last;
+
                     body.visit_with(child);
 
                     Ok(child.cur_facts.true_facts.take())
@@ -70,7 +88,22 @@ impl Analyzer<'_, '_> {
             facts_from_body.excludes.clear();
 
             if last {
-                prev_facts += facts_from_body;
+                match kind {
+                    LoopKind::DoWhile => {
+                        prev_facts += facts_from_body;
+                        prev_facts += facts_from_cond;
+                    }
+
+                    LoopKind::While => {
+                        prev_facts += facts_from_cond;
+                        prev_facts += facts_from_body;
+                    }
+
+                    _ => {
+                        prev_facts += facts_from_body;
+                    }
+                }
+
                 break;
             }
 
@@ -373,7 +406,16 @@ impl Analyzer<'_, '_> {
 
             child.validate_lhs_of_for_loop(left, &elem_ty, kind);
 
-            child.validate_loop_body_with_scope(None, body).report(&mut child.storage);
+            child
+                .validate_loop_body_with_scope(
+                    None,
+                    body,
+                    match kind {
+                        ForHeadKind::Of { is_awaited } => LoopKind::ForOf { is_awaited },
+                        ForHeadKind::In => LoopKind::ForIn,
+                    },
+                )
+                .report(&mut child.storage);
 
             Ok(())
         })?;
@@ -409,7 +451,7 @@ impl Analyzer<'_, '_> {
 #[validator]
 impl Analyzer<'_, '_> {
     fn validate(&mut self, node: &RWhileStmt) {
-        self.validate_loop_body_with_scope(Some(&node.test), &node.body)
+        self.validate_loop_body_with_scope(Some(&node.test), &node.body, LoopKind::While)
             .report(&mut self.storage);
 
         Ok(())
@@ -421,7 +463,7 @@ impl Analyzer<'_, '_> {
     fn validate(&mut self, node: &RDoWhileStmt) {
         node.body.visit_with(self);
 
-        self.validate_loop_body_with_scope(Some(&node.test), &node.body)
+        self.validate_loop_body_with_scope(Some(&node.test), &node.body, LoopKind::DoWhile)
             .report(&mut self.storage);
 
         Ok(())

crates/stc_ts_file_analyzer/tests/visualize/exprs/assign/typeNarrowing/.seq-1.ts → crates/stc_ts_file_analyzer/tests/pass-only/typeNarrowing/seq-1.ts

@@ -3,6 +3,8 @@ let obj: any;
 
 x = true;
 (x = "", obj).foo = (x = x.length);
-x; // number
+
+declare function assertNumber(n: number): void;
+assertNumber(x)
 
 export { }

crates/stc_ts_file_analyzer/tests/visualize/exprs/assign/typeNarrowing/.simple-1.ts → crates/stc_ts_file_analyzer/tests/pass-only/typeNarrowing/simple-1.ts

@@ -4,4 +4,5 @@ do {
     x; // number
     x = "";
 } while (x = x.length)
-x; // number
+declare function assertNumber(n: number): void;
+assertNumber(x)