From 218650dc85274532f97ab0a96aeb0724b4e01c91 Mon Sep 17 00:00:00 2001
From: chrchr-github <78114321+chrchr-github@users.noreply.github.com>
Date: Fri, 7 Jul 2023 23:30:59 +0200
Subject: [PATCH] Fix #11820 FP duplicateExpression with double negation
 (#5227)

---
 lib/astutils.cpp   | 4 ++--
 test/testother.cpp | 9 +++++++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/lib/astutils.cpp b/lib/astutils.cpp
index 268b9535b..7dea9a460 100644
--- a/lib/astutils.cpp
+++ b/lib/astutils.cpp
@@ -1458,10 +1458,10 @@ bool isSameExpression(bool cpp, bool macro, const Token *tok1, const Token *tok2
             tok2 = tok2->astOperand2();
     }
     // Skip double not
-    if (Token::simpleMatch(tok1, "!") && Token::simpleMatch(tok1->astOperand1(), "!") && !Token::simpleMatch(tok1->astParent(), "=")) {
+    if (Token::simpleMatch(tok1, "!") && Token::simpleMatch(tok1->astOperand1(), "!") && !Token::simpleMatch(tok1->astParent(), "=") && astIsBoolLike(tok2)) {
         return isSameExpression(cpp, macro, tok1->astOperand1()->astOperand1(), tok2, library, pure, followVar, errors);
     }
-    if (Token::simpleMatch(tok2, "!") && Token::simpleMatch(tok2->astOperand1(), "!") && !Token::simpleMatch(tok2->astParent(), "=")) {
+    if (Token::simpleMatch(tok2, "!") && Token::simpleMatch(tok2->astOperand1(), "!") && !Token::simpleMatch(tok2->astParent(), "=") && astIsBoolLike(tok1)) {
         return isSameExpression(cpp, macro, tok1, tok2->astOperand1()->astOperand1(), library, pure, followVar, errors);
     }
     const bool tok_str_eq = tok1->str() == tok2->str();
diff --git a/test/testother.cpp b/test/testother.cpp
index 1c0fb8b9f..91d1beef5 100644
--- a/test/testother.cpp
+++ b/test/testother.cpp
@@ -6570,6 +6570,15 @@ private:
               "    }\n"
               "}\n");
         ASSERT_EQUALS("[test.cpp:3] -> [test.cpp:4]: (style) The comparison 'p == 0' is always true.\n", errout.str());
+
+        // #11820
+        check("unsigned f(unsigned x) {\n"
+              "    return x - !!x;\n"
+              "}\n"
+              "unsigned g(unsigned x) {\n"
+              "    return !!x - x;\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void duplicateExpression8() {