fix(semantic): add cfg nodes for ConditionalExpressions. (#3127)

It is done similarly to how `IfStatement`s are structured at the moment.

crates/oxc_semantic/src/builder.rs

@@ -765,6 +765,54 @@ impl<'a> Visit<'a> for SemanticBuilder<'a> {
         self.leave_node(kind);
     }
 
+    fn visit_conditional_expression(&mut self, expr: &ConditionalExpression<'a>) {
+        let kind = AstKind::ConditionalExpression(self.alloc(expr));
+        self.enter_node(kind);
+
+        self.visit_expression(&expr.test);
+
+        /* cfg */
+        let before_conditional_expr_graph_ix = self.cfg.current_node_ix;
+        // conditional expression basic block
+        let before_consequent_expr_graph_ix = self.cfg.new_basic_block();
+        /* cfg */
+
+        self.visit_expression(&expr.consequent);
+
+        /* cfg */
+        let after_consequent_expr_graph_ix = self.cfg.current_node_ix;
+        let start_alternate_graph_ix = self.cfg.new_basic_block();
+        /* cfg */
+
+        self.visit_expression(&expr.alternate);
+
+        /* cfg */
+        let after_alternate_graph_ix = self.cfg.current_node_ix;
+        /* bb after conditional expression joins consequent and alternate */
+        let after_conditional_graph_ix = self.cfg.new_basic_block();
+        /* cfg */
+
+        self.cfg.put_unreachable();
+        self.cfg.add_edge(
+            after_consequent_expr_graph_ix,
+            after_conditional_graph_ix,
+            EdgeType::Normal,
+        );
+        self.cfg.add_edge(
+            before_conditional_expr_graph_ix,
+            before_consequent_expr_graph_ix,
+            EdgeType::Normal,
+        );
+
+        self.cfg.add_edge(
+            before_conditional_expr_graph_ix,
+            start_alternate_graph_ix,
+            EdgeType::Normal,
+        );
+        self.cfg.add_edge(after_alternate_graph_ix, after_conditional_graph_ix, EdgeType::Normal);
+        self.leave_node(kind);
+    }
+
     fn visit_for_statement(&mut self, stmt: &ForStatement<'a>) {
         let kind = AstKind::ForStatement(self.alloc(stmt));
         let is_lexical_declaration =

crates/oxc_semantic/tests/snapshots/cfg__cfg_files@cond_expr_in_arrow_fn.js-2.snap

@@ -6,6 +6,14 @@ input_file: crates/oxc_semantic/tests/cfg_fixtures/cond_expr_in_arrow_fn.js
 digraph {
     0 [ label = ""]
     1 [ label = ""]
+    2 [ label = ""]
+    3 [ label = ""]
+    4 [ label = ""]
+    5 [ label = "Unreachable()"]
     0 -> 1 [ ]
+    4 -> 5 [ ]
+    2 -> 4 [ ]
+    1 -> 2 [ ]
+    1 -> 3 [ ]
+    3 -> 4 [ ]
 }
-

crates/oxc_semantic/tests/snapshots/cfg__cfg_files@cond_expr_in_arrow_fn.js.snap

@@ -10,3 +10,19 @@ bb0: {
 bb1: {
 
 }
+
+bb2: {
+
+}
+
+bb3: {
+
+}
+
+bb4: {
+
+}
+
+bb5: {
+	Unreachable()
+}

crates/oxc_semantic/tests/snapshots/cfg__cfg_files@conditional_expression.js-2.snap

@@ -5,5 +5,13 @@ input_file: crates/oxc_semantic/tests/cfg_fixtures/conditional_expression.js
 ---
 digraph {
     0 [ label = ""]
+    1 [ label = ""]
+    2 [ label = ""]
+    3 [ label = ""]
+    4 [ label = "Unreachable()"]
+    3 -> 4 [ ]
+    1 -> 3 [ ]
+    0 -> 1 [ ]
+    0 -> 2 [ ]
+    2 -> 3 [ ]
 }
-

crates/oxc_semantic/tests/snapshots/cfg__cfg_files@conditional_expression.js.snap

@@ -6,3 +6,19 @@ input_file: crates/oxc_semantic/tests/cfg_fixtures/conditional_expression.js
 bb0: {
 
 }
+
+bb1: {
+
+}
+
+bb2: {
+
+}
+
+bb3: {
+
+}
+
+bb4: {
+	Unreachable()
+}