From eb3bf571beb317d6b80038e047497dcf4278c379 Mon Sep 17 00:00:00 2001
From: Simon Martin <simartin@users.sourceforge.net>
Date: Sun, 28 Jul 2013 12:32:18 +0200
Subject: [PATCH] Avoid divisions by zero when simplifying numeric
 calculations.

---
 lib/templatesimplifier.cpp |  2 +-
 test/testother.cpp         | 10 ++++++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/lib/templatesimplifier.cpp b/lib/templatesimplifier.cpp
index e63d8e8f6..a90612c84 100644
--- a/lib/templatesimplifier.cpp
+++ b/lib/templatesimplifier.cpp
@@ -766,7 +766,7 @@ bool TemplateSimplifier::simplifyNumericCalculations(Token *tok)
     while (tok->tokAt(4) && tok->next()->isNumber() && tok->tokAt(3)->isNumber()) { // %any% %num% %any% %num% %any%
         const Token* op = tok->tokAt(2);
         const Token* after = tok->tokAt(4);
-        if (Token::Match(tok, "* %num% /") && tok->next()->str() == MathLib::multiply(tok->strAt(3), MathLib::divide(tok->next()->str(), tok->strAt(3)))) {
+        if (Token::Match(tok, "* %num% /") && (tok->strAt(3) != "0") && tok->next()->str() == MathLib::multiply(tok->strAt(3), MathLib::divide(tok->next()->str(), tok->strAt(3)))) {
             // Division where result is a whole number
         } else if (!((op->str() == "*" && (isLowerThanMulDiv(tok) || tok->str() == "*") && isLowerEqualThanMulDiv(after)) || // associative
                      (Token::Match(op, "[/%]") && isLowerThanMulDiv(tok) && isLowerEqualThanMulDiv(after)) || // NOT associative
diff --git a/test/testother.cpp b/test/testother.cpp
index 4e1d99c6a..3cdc46f07 100644
--- a/test/testother.cpp
+++ b/test/testother.cpp
@@ -42,6 +42,7 @@ private:
         TEST_CASE(zeroDiv4);
         TEST_CASE(zeroDiv5);
         TEST_CASE(zeroDiv6);
+        TEST_CASE(zeroDiv7);  // #4930
 
         TEST_CASE(nanInArithmeticExpression);
 
@@ -414,6 +415,15 @@ private:
               "} } }");
         ASSERT_EQUALS("[test.cpp:3]: (error) Division by zero.\n", errout.str());
     }
+    
+    void zeroDiv7() {
+        check("void f() {\n"
+              "  int a = 1/2*3/0;\n"
+              "  int b = 1/2*3%0;\n"
+              "}");
+        ASSERT_EQUALS("[test.cpp:2]: (error) Division by zero.\n"
+                      "[test.cpp:3]: (error) Division by zero.\n", errout.str());
+    }
 
     void nanInArithmeticExpression() {
         check("void f()\n"