Fix #168: ClearConst() does not clear m_vStringVarBuf

CHANGELOG

@@ -28,6 +28,11 @@ Rev 2.3.6: 07.03.2026
   Fixes:
    * Fix for #167 (https://github.com/beltoforion/muparser/pull/167):
      Added additional range checks for accessing internal value stack.
+   * Fix for #168 (https://github.com/beltoforion/muparser/pull/169):
+     ClearConst() now also clears m_vStringVarBuf to keep it in sync
+     with m_StrVarDef. Previously, repeated calls to ClearConst()
+     followed by DefineStrConst() caused stale entries to accumulate
+     in the string value buffer.
 
 
 Rev 2.3.5: 13.12.2024

README.md

@@ -18,6 +18,7 @@ Change Notes for Revision 2.3.6 (2026-04-10)
   Security Fixes:
   -----------
   - Issue https://github.com/beltoforion/muparser/issues/167: Add additional checks to eliminate possibility of access violations due to malformed expressions. I dont have test cases and do not know whether this issue was exploitable at all but fixing them made sense.
+  - Issue https://github.com/beltoforion/muparser/issues/168: ClearConst() now also clears the internal string variable buffer (m_vStringVarBuf) to keep it in sync with the name-to-index map (m_StrVarDef). Previously stale entries accumulated across repeated ClearConst() calls.
 
   Fixed Compiler Warnings and Errors:
   -----------

include/muParserTest.h

@@ -267,7 +267,8 @@ namespace mu
 			int TestOptimizer();
 			int TestLocalization();
 			int TestIssue165();
-
+			int TestIssue168();
+
 			void Abort() const;
 
 		public:

src/muParserBase.cpp

@@ -1637,6 +1637,7 @@ namespace mu
 	{
 		m_ConstDef.clear();
 		m_StrVarDef.clear();
+		m_vStringVarBuf.clear();
 		ReInit();
 	}
 

src/muParserTest.cpp

@@ -65,6 +65,7 @@ namespace mu
 			AddTest(&ParserTester::TestOptimizer);
 			AddTest(&ParserTester::TestLocalization);
 			AddTest(&ParserTester::TestIssue165);
+		AddTest(&ParserTester::TestIssue168);
 
 			ParserTester::c_iCount = 0;
 		}
@@ -1751,6 +1752,61 @@ namespace mu
 			return iRet;
 		}
 
+		//---------------------------------------------------------------------------
+		// Regression test: ClearConst() must also clear m_vStringVarBuf.
+		//
+		// Currently ClearConst() clears m_StrVarDef but not m_vStringVarBuf, so
+		// the value buffer silently accumulates stale entries across calls.  After
+		// one round of DefineStrConst + ClearConst + DefineStrConst the buffer
+		// should have 2 entries (not 4).  This test will FAIL until the bug is fixed.
+		int ParserTester::TestIssue168()
+		{
+			ParserTester::c_iCount++;
+			int iRet(0);
+
+			mu::console() << _T("testing github issue 168...");
+
+			try
+			{
+				Parser p;
+				p.DefineFun(_T("strlen"), StrLen);
+
+				p.DefineStrConst(_T("s1"), _T("hello"));
+				p.DefineStrConst(_T("s2"), _T("world"));
+				p.SetExpr(_T("strlen(s1)+strlen(s2)"));
+				p.Eval();
+
+				p.ClearConst();
+
+				p.DefineStrConst(_T("s1"), _T("hi"));
+				p.DefineStrConst(_T("s2"), _T("!"));
+				p.SetExpr(_T("strlen(s1)+strlen(s2)"));
+				p.Eval();
+
+				// After ClearConst + re-registration the buffer should hold exactly
+				// 2 entries.  If ClearConst does not clear it, the buffer has 4.
+				std::size_t sz = p.m_vStringVarBuf.size();
+				if (sz != 2)
+				{
+					mu::console() << _T("\n  fail: m_vStringVarBuf.size() == ") << sz
+					              << _T(" (expected 2 — ClearConst does not clear the buffer)");
+					iRet++;
+				}
+
+				if (iRet == 0)
+					mu::console() << _T("passed") << endl;
+				else
+					mu::console() << _T("\n  failed with ") << iRet << _T(" errors") << endl;
+			}
+			catch (...)
+			{
+				mu::console() << _T("\n  fail: unexpected exception");
+				return 1;
+			}
+
+			return iRet;
+		}
+
 		//---------------------------------------------------------------------------
 		int ParserTester::EqnTestInt(const string_type& a_str, double a_fRes, bool a_fPass)
 		{