Fixed issue #964. Assign operator crashes math parser.

(grafted from 9fd845b77249b4edc1bdc0a42dc4b32fb5f036f6)

--HG--
branch : develop

ChangeLog.txt

@@ -36,6 +36,7 @@
 - [#957] Unable to cut an arc with negative length.
 - [#962] Failed to load LibEGL.
 - [#963] Bug in tool Point intersect curve and axis.
+- [#964] Assign operator crashes math parser.
 
 # Version 0.6.1 October 23, 2018
 - [#885] Regression. Broken support for multi size measurements.

src/libs/qmuparser/qmuparserbase.cpp

@@ -915,7 +915,11 @@ void QmuParserBase::ApplyBinOprt(QStack<token_type> &a_stOpt, QStack<token_type>
     }
     else
     {
-        Q_ASSERT(a_stVal.size()>=2);
+        if(a_stVal.size()<2)
+        {
+            Error(ecUNEXPECTED_OPERATOR);
+        }
+
         token_type valTok1 = a_stVal.pop(),
                    valTok2 = a_stVal.pop(),
                    optTok  = a_stOpt.pop(),
@@ -930,7 +934,7 @@ void QmuParserBase::ApplyBinOprt(QStack<token_type> &a_stOpt, QStack<token_type>
         {
             if (valTok2.GetCode()!=cmVAR)
             {
-                Error(ecUNEXPECTED_OPERATOR, -1, "=");
+                Error(ecUNEXPECTED_OPERATOR, -1, QChar('='));
             }
             m_vRPN.AddAssignOp(valTok2.GetVar());
         }

src/libs/qmuparser/qmuparsertest.cpp

@@ -266,6 +266,7 @@ int QmuParserTester::TestBinOprt()
     iStat += EqnTest ( "2*(a=b+1)", 6, true );
     iStat += EqnTest ( "(a=b+1)*2", 6, true );
     iStat += EqnTest ( "a=c; a*10", 30, true);
+    iStat += EqnTest ( "a = -", 0, false );    // broken assigment
 
     iStat += EqnTest ( "2^2^3", 256, true );
     iStat += EqnTest ( "1/2/3", 1.0 / 6.0, true );