C++: Split valuetext off into its own table

Author: ian-semmle

cpp/ql/src/semmle/code/cpp/exprs/Expr.qll

@@ -85,10 +85,10 @@ class Expr extends StmtParent, @expr {
   override string toString() { none() }
 
   /** Gets the value of this expression, if it is a constant. */
-  string getValue() { exists(@value v | values(v,result,_) and valuebind(v,underlyingElement(this))) }
+  string getValue() { exists(@value v | values(v,result) and valuebind(v,underlyingElement(this))) }
 
   /** Gets the source text for the value of this expression, if it is a constant. */
-  string getValueText() { exists(@value v | values(v,_,result) and valuebind(v,underlyingElement(this))) }
+  string getValueText() { exists(@value v | valuetext(v,result) and valuebind(v,underlyingElement(this))) }
 
   /** Holds if this expression has a value that can be determined at compile time. */
   cached

cpp/ql/src/semmlecode.cpp.dbscheme

@@ -1237,11 +1237,15 @@ expr_cond_false(
     int false: @expr ref
 );
 
-// the second field is a string representation of the value
-// the third field is the actual text in the source or the same as the second field
+/** A string representation of the value. */
 values(
     unique int id: @value,
-    string str: string ref,
+    string str: string ref
+);
+
+/** The actual text in the source code for the value, if any. */
+valuetext(
+    unique int id: @value ref,
     string text: string ref
 );