From d123279fc13e51ab9cb7d08065558c08103d16d3 Mon Sep 17 00:00:00 2001
From: Paul Fultz II <pfultz2@yahoo.com>
Date: Thu, 14 May 2020 07:10:32 -0500
Subject: [PATCH] Fix issue 9709: ValueFlow: variable value is not known
 (#2643)

---
 lib/programmemory.cpp  |  4 ++++
 test/testcondition.cpp | 12 ++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/lib/programmemory.cpp b/lib/programmemory.cpp
index 770cfd0e1..a6a3f9955 100644
--- a/lib/programmemory.cpp
+++ b/lib/programmemory.cpp
@@ -199,6 +199,10 @@ static void fillProgramMemoryFromAssignments(ProgramMemory& pm, const Token* tok
                 else
                     pm.setUnknown(vartok->varId());
             }
+        } else if (!setvar && Token::Match(tok2, "%var% !!=") && isVariableChanged(tok2, 0, nullptr, true)) {
+            const Token *vartok = tok2;
+            if (!pm.hasValue(vartok->varId()))
+                pm.setUnknown(vartok->varId());
         }
 
         if (tok2->str() == "{") {
diff --git a/test/testcondition.cpp b/test/testcondition.cpp
index b63d7c2b5..dc8c193ae 100644
--- a/test/testcondition.cpp
+++ b/test/testcondition.cpp
@@ -3366,6 +3366,18 @@ private:
               "    if (!x) {}\n"
               "}\n");
         ASSERT_EQUALS("", errout.str());
+
+        // #9709
+        check("void f(int a) {\n"
+              "    bool ok = false;\n"
+              "    const char * r = nullptr;\n"
+              "    do_something(&r);\n"
+              "    if (r != nullptr)\n"
+              "        ok = a != 0;\n"
+              "    if (ok) {}\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
+
     }
 
     void alwaysTrueInfer() {