C++: Add value category column to the expr_reuse relation

cpp/downgrades/abfce5c170f93e281948f7689ece373464fdaf87/expr_reuse.ql

@@ -0,0 +1,7 @@
+class Expr extends @expr {
+  string toString() { none() }
+}
+
+from Expr reuse, Expr original
+where expr_reuse(reuse, original, _)
+select reuse, original

cpp/downgrades/abfce5c170f93e281948f7689ece373464fdaf87/expr_types.ql

@@ -0,0 +1,22 @@
+class Expr extends @expr {
+  string toString() { none() }
+}
+
+class Type extends @type {
+  string toString() { none() }
+}
+
+predicate existingType(Expr expr, Type type, int value_category) {
+  expr_types(expr, type, value_category)
+}
+
+predicate reuseType(Expr reuse, Type type, int value_category) {
+  exists(Expr original |
+    expr_reuse(reuse, original, value_category) and
+    expr_types(original, type, _)
+  )
+}
+
+from Expr expr, Type type, int value_category
+where existingType(expr, type, value_category) or reuseType(expr, type, value_category)
+select expr, type, value_category

cpp/downgrades/abfce5c170f93e281948f7689ece373464fdaf87/upgrade.properties

@@ -0,0 +1,4 @@
+description: Add value category to expr_reuse table
+compatibility: full
+expr_reuse.rel: run expr_reuse.qlo
+expr_types.rel: run expr_types.qlo

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

@@ -1340,5 +1340,13 @@ class ReuseExpr extends Expr, @reuseexpr {
   /**
    * Gets the expression that is being re-used.
    */
-  Expr getReusedExpr() { expr_reuse(underlyingElement(this), unresolveElement(result)) }
+  Expr getReusedExpr() { expr_reuse(underlyingElement(this), unresolveElement(result), _) }
+
+  override Type getType() { result = this.getReusedExpr().getType() }
+
+  override predicate isLValueCategory() { expr_reuse(underlyingElement(this), _, 3) }
+
+  override predicate isXValueCategory() { expr_reuse(underlyingElement(this), _, 2) }
+
+  override predicate isPRValueCategory() { expr_reuse(underlyingElement(this), _, 1) }
 }

cpp/ql/lib/semmlecode.cpp.dbscheme

@@ -1515,7 +1515,8 @@ exprs(
 
 expr_reuse(
     int reuse: @expr ref,
-    int original: @expr ref
+    int original: @expr ref,
+    int value_category: int ref
 )
 
 /*

cpp/ql/lib/upgrades/aa7ff0ab32cd4674f6ab731d32fea64116997b05/expr_reuse.ql

@@ -0,0 +1,7 @@
+class Expr extends @expr {
+  string toString() { none() }
+}
+
+from Expr reuse, Expr original, int value_category
+where expr_reuse(reuse, original) and expr_types(original, _, value_category)
+select reuse, original, value_category

cpp/ql/lib/upgrades/aa7ff0ab32cd4674f6ab731d32fea64116997b05/upgrade.properties

@@ -0,0 +1,3 @@
+description: Add value category to expr_reuse table
+compatibility: full
+expr_reuse.rel: run expr_reuse.qlo