From dda12752c2b2e5717982beeccbebb5aab8865ff1 Mon Sep 17 00:00:00 2001
From: Gary Feng <104392015+gfeng-certik@users.noreply.github.com>
Date: Fri, 27 Jan 2023 16:41:17 -0500
Subject: [PATCH] fix: finish connecting true-statement node to end-if node
 before connecting condition node to false-statement node (#23)

- fixes the issue with wrong if-statement CFG when the then-clause is empty.

https://github.com/CertiKProject/slither-task/issues/241
---
 slither/solc_parsing/declarations/function.py | 23 +++++++++----------
 1 file changed, 11 insertions(+), 12 deletions(-)

diff --git a/slither/solc_parsing/declarations/function.py b/slither/solc_parsing/declarations/function.py
index d1465bb0f9..070b5fcdb2 100644
--- a/slither/solc_parsing/declarations/function.py
+++ b/slither/solc_parsing/declarations/function.py
@@ -362,7 +362,7 @@ def _new_yul_block(
 
     def _parse_if(self, if_statement: Dict, node: NodeSolc) -> NodeSolc:
         # IfStatement = 'if' '(' Expression ')' Statement ( 'else' Statement )?
-        falseStatement = None
+        false_body = None
 
         if self.is_compact_ast:
             condition = if_statement["condition"]
@@ -379,13 +379,9 @@ def _parse_if(self, if_statement: Dict, node: NodeSolc) -> NodeSolc:
             trueStatement = self._parse_statement(
                 if_statement["trueBody"], condition_node, true_scope
             )
+
             if "falseBody" in if_statement and if_statement["falseBody"]:
-                false_scope = Scope(
-                    node.underlying_node.scope.is_checked, False, node.underlying_node.scope
-                )
-                falseStatement = self._parse_statement(
-                    if_statement["falseBody"], condition_node, false_scope
-                )
+                false_body = if_statement["falseBody"]
         else:
             children = if_statement[self.get_children("children")]
             condition = children[0]
@@ -400,19 +396,22 @@ def _parse_if(self, if_statement: Dict, node: NodeSolc) -> NodeSolc:
                 node.underlying_node.scope.is_checked, False, node.underlying_node.scope
             )
             trueStatement = self._parse_statement(children[1], condition_node, true_scope)
+
             if len(children) == 3:
-                false_scope = Scope(
-                    node.underlying_node.scope.is_checked, False, node.underlying_node.scope
-                )
-                falseStatement = self._parse_statement(children[2], condition_node, false_scope)
+                false_body = children[2]
 
         endIf_node = self._new_node(NodeType.ENDIF, if_statement["src"], node.underlying_node.scope)
         link_underlying_nodes(trueStatement, endIf_node)
 
-        if falseStatement:
+        if false_body:
+            false_scope = Scope(
+                node.underlying_node.scope.is_checked, False, node.underlying_node.scope
+            )
+            falseStatement = self._parse_statement(false_body, condition_node, false_scope)
             link_underlying_nodes(falseStatement, endIf_node)
         else:
             link_underlying_nodes(condition_node, endIf_node)
+
         return endIf_node
 
     def _parse_while(self, whilte_statement: Dict, node: NodeSolc) -> NodeSolc: