From 9f7a0146d0bde3ef6e6c0be0a634c58d7b7b76c4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Marjam=C3=A4ki?= <daniel.marjamaki@gmail.com>
Date: Wed, 26 Sep 2012 20:15:46 +0200
Subject: [PATCH] AssignIf: Detect mistake in such code: 'int x=y&4; if
 ((x==3)||..'

---
 lib/checkassignif.cpp | 18 +++++++++++-------
 lib/checkassignif.h   |  4 ++--
 test/testassignif.cpp |  6 ++++++
 3 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/lib/checkassignif.cpp b/lib/checkassignif.cpp
index 8f61b74c2..484d587af 100644
--- a/lib/checkassignif.cpp
+++ b/lib/checkassignif.cpp
@@ -54,13 +54,17 @@ void CheckAssignIf::assignIf()
             for (const Token *tok2 = tok->tokAt(4); tok2; tok2 = tok2->next()) {
                 if (tok2->str() == "(" || tok2->str() == "}" || tok2->str() == "=")
                     break;
-                if (Token::Match(tok2,"if ( %varid% %any% %num% &&|%oror%|)", varid)) {
-                    const std::string& op(tok2->strAt(3));
-                    const MathLib::bigint num2 = MathLib::toLongNumber(tok2->strAt(4));
+                if (Token::Match(tok2,"if ( (| %varid% %any% %num% &&|%oror%|)", varid)) {
+                    const Token *vartok = tok2->tokAt(tok2->strAt(2)=="(" ? 3 : 2);
+                    const std::string& op(vartok->strAt(1));
+                    const MathLib::bigint num2 = MathLib::toLongNumber(vartok->strAt(2));
+                    std::string condition;
+                    if (Token::simpleMatch(tok2, "if ( ("))
+                        condition = "'" + vartok->str() + op + vartok->strAt(2) + "'";
                     if (op == "==" && (num & num2) != ((bitop=='&') ? num2 : num))
-                        assignIfError(tok2, false);
+                        assignIfError(tok2, condition, false);
                     else if (op == "!=" && (num & num2) != ((bitop=='&') ? num2 : num))
-                        assignIfError(tok2, true);
+                        assignIfError(tok2, condition, true);
                     break;
                 }
             }
@@ -68,11 +72,11 @@ void CheckAssignIf::assignIf()
     }
 }
 
-void CheckAssignIf::assignIfError(const Token *tok, bool result)
+void CheckAssignIf::assignIfError(const Token *tok, const std::string &condition, bool result)
 {
     reportError(tok, Severity::style,
                 "assignIfError",
-                "Mismatching assignment and comparison, comparison is always " + std::string(result ? "true" : "false") + ".");
+                "Mismatching assignment and comparison, comparison " + condition + (condition.empty()?"":" ") + "is always " + std::string(result ? "true" : "false") + ".");
 }
 
 
diff --git a/lib/checkassignif.h b/lib/checkassignif.h
index e72438ba4..7c1f50d89 100644
--- a/lib/checkassignif.h
+++ b/lib/checkassignif.h
@@ -63,7 +63,7 @@ public:
 
 private:
 
-    void assignIfError(const Token *tok, bool result);
+    void assignIfError(const Token *tok, const std::string &condition, bool result);
 
     void comparisonError(const Token *tok,
                          const std::string &bitop,
@@ -76,7 +76,7 @@ private:
 
     void getErrorMessages(ErrorLogger *errorLogger, const Settings *settings) const {
         CheckAssignIf c(0, settings, errorLogger);
-        c.assignIfError(0, false);
+        c.assignIfError(0, "", false);
         c.comparisonError(0, "&", 6, "==", 1, false);
         c.multiConditionError(0,1);
     }
diff --git a/test/testassignif.cpp b/test/testassignif.cpp
index 58b6247d5..5701687aa 100644
--- a/test/testassignif.cpp
+++ b/test/testassignif.cpp
@@ -74,6 +74,12 @@ private:
               "}\n");
         ASSERT_EQUALS("[test.cpp:4]: (style) Mismatching assignment and comparison, comparison is always true.\n", errout.str());
 
+        check("void foo(int x) {\n"
+              "    int y = x & 4;\n"
+              "    if ((y == 3) && (z == 1));\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:3]: (style) Mismatching assignment and comparison, comparison 'y==3' is always false.\n", errout.str());
+
         // |
         check("void foo(int x) {\n"
               "    int y = x | 0x14;\n"