libexpr: allocate ExprOpHasAttr's AttrPath in Exprs::alloc

Author: Radvendii

src/libexpr/include/nix/expr/nixexpr.hh

@@ -342,10 +342,16 @@ struct ExprSelect : Expr
 struct ExprOpHasAttr : Expr
 {
     Expr * e;
-    AttrPath attrPath;
-    ExprOpHasAttr(Expr * e, AttrPath attrPath)
+    std::span<AttrName> attrPath;
+
+    ExprOpHasAttr(std::pmr::polymorphic_allocator<char> alloc, Expr * e, std::vector<AttrName> attrPath)
         : e(e)
-        , attrPath(std::move(attrPath)) {};
+    {
+        auto nAttrPath = attrPath.size();
+        auto attrPathStart = (AttrName *) alloc.allocate(nAttrPath * sizeof(AttrName));
+        memcpy(attrPathStart, attrPath.data(), nAttrPath * sizeof(AttrName));
+        this->attrPath = {attrPathStart, nAttrPath};
+    };
 
     PosIdx getPos() const override
     {

src/libexpr/parser.y

@@ -261,7 +261,7 @@ expr_op
   | expr_op OR expr_op { $$ = new ExprOpOr(state->at(@2), $1, $3); }
   | expr_op IMPL expr_op { $$ = new ExprOpImpl(state->at(@2), $1, $3); }
   | expr_op UPDATE expr_op { $$ = new ExprOpUpdate(state->at(@2), $1, $3); }
-  | expr_op '?' attrpath { $$ = new ExprOpHasAttr($1, std::move(*$3)); delete $3; }
+  | expr_op '?' attrpath { $$ = new ExprOpHasAttr(state->alloc, $1, std::move(*$3)); delete $3; }
   | expr_op '+' expr_op
     { $$ = new ExprConcatStrings(state->at(@2), false, new std::vector<std::pair<PosIdx, Expr *> >({{state->at(@1), $1}, {state->at(@3), $3}})); }
   | expr_op '-' expr_op { $$ = new ExprCall(state->at(@2), new ExprVar(state->s.sub), {$1, $3}); }