From 45ccc9ba1ee7eeaf3657e42087feece0588adf38 Mon Sep 17 00:00:00 2001
From: chrchr-github <78114321+chrchr-github@users.noreply.github.com>
Date: Fri, 16 Sep 2022 12:11:34 +0200
Subject: [PATCH] Fix ctunullpointer FP (#4471)

---
 lib/checknullpointer.cpp | 8 +++++++-
 test/testnullpointer.cpp | 9 +++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/lib/checknullpointer.cpp b/lib/checknullpointer.cpp
index 4fbe58785..b895c6bbd 100644
--- a/lib/checknullpointer.cpp
+++ b/lib/checknullpointer.cpp
@@ -146,6 +146,12 @@ bool CheckNullPointer::isPointerDeRef(const Token *tok, bool &unknown) const
     return isPointerDeRef(tok, unknown, mSettings);
 }
 
+static bool isUnevaluated(const Token* tok) {
+    if (tok && Token::Match(tok->previous(), "sizeof|decltype ("))
+        return true;
+    return false;
+}
+
 bool CheckNullPointer::isPointerDeRef(const Token *tok, bool &unknown, const Settings *settings)
 {
     unknown = false;
@@ -182,7 +188,7 @@ bool CheckNullPointer::isPointerDeRef(const Token *tok, bool &unknown, const Set
         return false;
 
     // Dereferencing pointer..
-    if (parent->isUnaryOp("*")) {
+    if (parent->isUnaryOp("*") && !isUnevaluated(parent->astParent())) {
         // declaration of function pointer
         if (tok->variable() && tok->variable()->nameToken() == tok)
             return false;
diff --git a/test/testnullpointer.cpp b/test/testnullpointer.cpp
index e0475c95b..e86cebd83 100644
--- a/test/testnullpointer.cpp
+++ b/test/testnullpointer.cpp
@@ -4341,6 +4341,15 @@ private:
             "        g(x);\n"
             "}");
         ASSERT_EQUALS("", errout.str());
+
+        ctu("size_t f(int* p) {\n"
+            "    size_t len = sizeof(*p);\n"
+            "    return len;\n"
+            "}\n"
+            "void g() {\n"
+            "    f(NULL);\n"
+            "}\n");
+        ASSERT_EQUALS("", errout.str());
     }
 };