From fe80f858d16b223264a116733c79a628d57b46bd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Marjam=C3=A4ki?= <daniel.marjamaki@gmail.com>
Date: Tue, 22 Apr 2014 16:10:20 +0200
Subject: [PATCH] ValueFlow: Improved analysis in the valueFlowAfterAssign

---
 lib/valueflow.cpp      | 19 ++++++++++++++++---
 test/testvalueflow.cpp | 10 ++++++++++
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/lib/valueflow.cpp b/lib/valueflow.cpp
index 4ca41170f..87a4c0e9c 100644
--- a/lib/valueflow.cpp
+++ b/lib/valueflow.cpp
@@ -527,17 +527,30 @@ static void valueFlowAfterAssign(TokenList *tokenlist, ErrorLogger *errorLogger,
             continue;
         std::list<ValueFlow::Value> values = tok->astOperand2()->values;
 
+        const bool constValue = tok->astOperand2()->isNumber();
+        int indentlevel = 0;
         unsigned int number_of_if = 0;
+        int varusagelevel = -1;
 
         for (Token *tok2 = tok; tok2 && tok2 != endToken; tok2 = tok2->next()) {
+            if (indentlevel >= 0 && tok2->str() == "{")
+                ++indentlevel;
+            else if (indentlevel >= 0 && tok2->str() == "}")
+                --indentlevel;
+
             if (Token::Match(tok2, "sizeof|typeof|typeid ("))
                 tok2 = tok2->linkAt(1);
 
             // conditional block of code that assigns variable..
-            if (Token::Match(tok2, "%var% (") && Token::simpleMatch(tok2->linkAt(1), ") {")) {
+            else if (Token::Match(tok2, "%var% (") && Token::simpleMatch(tok2->linkAt(1), ") {")) {
                 Token * const start = tok2->linkAt(1)->next();
                 Token * const end   = start->link();
-                if (Token::findmatch(start, "%varid%", end, varid)) {
+                bool varusage = (indentlevel >= 0 && constValue && number_of_if == 0U) ?
+                                isVariableChanged(start,end,varid) :
+                                (nullptr != Token::findmatch(start, "%varid%", end, varid));
+                if (varusage) {
+                    varusagelevel = indentlevel;
+
                     // TODO: don't check noreturn scopes
                     if (number_of_if > 0U || Token::findmatch(tok2, "%varid%", start, varid)) {
                         if (settings->debugwarnings)
@@ -586,7 +599,7 @@ static void valueFlowAfterAssign(TokenList *tokenlist, ErrorLogger *errorLogger,
                 }
             }
 
-            else if (tok2->str() == "}") {
+            else if (tok2->str() == "}" && indentlevel == varusagelevel) {
                 ++number_of_if;
 
                 // Set "conditional" flag for all values
diff --git a/test/testvalueflow.cpp b/test/testvalueflow.cpp
index 8f5a08795..16ca334be 100644
--- a/test/testvalueflow.cpp
+++ b/test/testvalueflow.cpp
@@ -594,6 +594,16 @@ private:
                "}";
         TODO_ASSERT_EQUALS(true, false, testValueOfX(code, 4U, 32));
 
+        code = "void f() {\n"
+               "    int x = 32;\n"
+               "    if (a==1) { z=x+12; }\n"
+               "    if (a==2) { z=x+32; }\n"
+               "    z = x;\n"
+               "}";
+        ASSERT_EQUALS(true, testValueOfX(code, 3U, 32));
+        ASSERT_EQUALS(true, testValueOfX(code, 4U, 32));
+        ASSERT_EQUALS(true, testValueOfX(code, 5U, 32));
+
         code = "void f() {\n" // #5656 - FP
                "    int x = 0;\n"
                "    if (!x) {\n"