From 13761927ffadc77c16afec11812ab3e6d05cf338 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Marjam=C3=A4ki?= <daniel.marjamaki@gmail.com>
Date: Wed, 18 Jun 2014 06:57:48 +0200
Subject: [PATCH] ValueFlow: better analysis in valueFlowAfterCondition of
 'if|while ( %var% )' etc

---
 lib/valueflow.cpp      | 13 +++++++++++--
 test/testvalueflow.cpp | 10 ++++++++++
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/lib/valueflow.cpp b/lib/valueflow.cpp
index 7bcb1fff5..e0946d304 100644
--- a/lib/valueflow.cpp
+++ b/lib/valueflow.cpp
@@ -780,14 +780,23 @@ static void valueFlowAfterCondition(TokenList *tokenlist, ErrorLogger *errorLogg
             }
             if (!vartok->isName() || !numtok->isNumber())
                 continue;
+
         } else if (tok->str() == "!") {
             vartok = tok->astOperand1();
             numtok = nullptr;
             if (!vartok || !vartok->isName())
                 continue;
+
+        } else if (tok->isName() &&
+                   (Token::Match(tok->astParent(), "%oror%|&&") ||
+                    Token::Match(tok->tokAt(-2), "if|while ( %var% )"))) {
+            vartok = tok;
+            numtok = nullptr;
+
         } else {
             continue;
         }
+
         const unsigned int varid = vartok->varId();
         if (varid == 0U)
             continue;
@@ -821,11 +830,11 @@ static void valueFlowAfterCondition(TokenList *tokenlist, ErrorLogger *errorLogg
             Token *startToken = nullptr;
             if (Token::Match(tok, "==|>=|<=|!") && Token::simpleMatch(top->link(), ") {"))
                 startToken = top->link()->next();
-            else if (tok->str() == "!=" && Token::simpleMatch(top->link()->linkAt(1), "} else {"))
+            else if (Token::Match(tok, "%var%|!=") && Token::simpleMatch(top->link()->linkAt(1), "} else {"))
                 startToken = top->link()->linkAt(1)->tokAt(2);
             bool ok = true;
             if (startToken)
-                ok &= valueFlowForward(startToken->next(), startToken->link(), var, varid, values, true, tokenlist, errorLogger, settings);
+                ok = valueFlowForward(startToken->next(), startToken->link(), var, varid, values, true, tokenlist, errorLogger, settings);
 
             // After conditional code..
             if (ok && !scopeEnd.empty() && Token::simpleMatch(top->link(), ") {")) {
diff --git a/test/testvalueflow.cpp b/test/testvalueflow.cpp
index 7d3e31802..59de3827c 100644
--- a/test/testvalueflow.cpp
+++ b/test/testvalueflow.cpp
@@ -761,6 +761,16 @@ private:
                "}";
         ASSERT_EQUALS(true, testValueOfX(code, 2U, 0));
 
+        // if (var)
+        code = "void f(int x) {\n"
+               "    if (x) { a = x; }\n"  // <- x is not 0
+               "    else { b = x; }\n"    // <- x is 0
+               "    c = x;\n"             // <- x might be 0
+               "}";
+        ASSERT_EQUALS(false, testValueOfX(code, 2U, 0));
+        ASSERT_EQUALS(true,  testValueOfX(code, 3U, 0));
+        ASSERT_EQUALS(true,  testValueOfX(code, 4U, 0));
+
         // After while
         code = "void f(int x) {\n"
                "    while (x != 3) {}\n"