From 8203c74c40b1c800612eafe32347601e54c27bad Mon Sep 17 00:00:00 2001
From: chrchr-github <78114321+chrchr-github@users.noreply.github.com>
Date: Wed, 13 Apr 2022 18:21:56 +0200
Subject: [PATCH] Fix #9648 FP sizeofDivisionMemfunc (#4017)

* Fix #9648 FP sizeofDivisionMemfunc when result is multiplied again with sizeof later

* Format
---
 lib/checksizeof.cpp | 13 +++++++++++++
 test/testsizeof.cpp |  8 ++++++++
 2 files changed, 21 insertions(+)

diff --git a/lib/checksizeof.cpp b/lib/checksizeof.cpp
index 21a29f273..3c95a60ab 100644
--- a/lib/checksizeof.cpp
+++ b/lib/checksizeof.cpp
@@ -165,6 +165,19 @@ void CheckSizeof::checkSizeofForPointerSize()
                             if (vt && vt->type == ValueType::CHAR && vt->pointer == 0)
                                 continue;
                         }
+                        auto hasMultiplication = [](const Token* parTok) -> bool {
+                            while (parTok) { // Allow division if followed by multiplication
+                                if (parTok->isArithmeticalOp() && parTok->str() == "*") {
+                                    for (const Token* szTok : { parTok->astOperand1(), parTok->astOperand2() })
+                                        if (Token::simpleMatch(szTok, "(") && Token::simpleMatch(szTok->previous(), "sizeof"))
+                                            return true;
+                                }
+                                parTok = parTok->astParent();
+                            }
+                            return false;
+                        };
+                        if (hasMultiplication(tok2->astParent()))
+                            continue;
 
                         divideBySizeofError(tok2, tokFunc->str());
                     }
diff --git a/test/testsizeof.cpp b/test/testsizeof.cpp
index 77e19f3dc..b23f033c4 100644
--- a/test/testsizeof.cpp
+++ b/test/testsizeof.cpp
@@ -785,6 +785,14 @@ private:
               "  strncpy(str, xyz, sizeof(str)/sizeof(str[0]));\n"
               "}");
         ASSERT_EQUALS("", errout.str());
+
+        check("void f() {\n" // #9648
+              "    int a[5] = { 0 };\n"
+              "    int b[5];\n"
+              "    memcpy(b, a, ((sizeof(a) / sizeof(a[0])) - 1) * sizeof(a[0]));\n"
+              "    memcpy(b, a, sizeof(a[0]) * ((sizeof(a) / sizeof(a[0])) - 1));\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void sizeofVoid() {