Fix underflow in Printer::printList

Analogous to 9b88bf8adf / three commits back

src/libexpr/print.cc

@@ -405,11 +405,14 @@ private:
             output << "[";
             auto listItems = v.listItems();
             auto prettyPrint = shouldPrettyPrintList(listItems);
+
+            size_t currentListItemsPrinted = 0;
+
             for (auto elem : listItems) {
                 printSpace(prettyPrint);
 
                 if (totalListItemsPrinted >= options.maxListItems) {
-                    printElided(listItems.size() - totalListItemsPrinted, "item", "items");
+                    printElided(listItems.size() - currentListItemsPrinted, "item", "items");
                     break;
                 }
 
@@ -419,6 +422,7 @@ private:
                     printNullptr();
                 }
                 totalListItemsPrinted++;
+                currentListItemsPrinted++;
             }
 
             decreaseIndent();

tests/functional/lang/eval-fail-nested-list-items.err.exp

@@ -0,0 +1,9 @@
+error:
+       … while evaluating a path segment
+         at /pwd/lang/eval-fail-nested-list-items.nix:11:6:
+           10|
+           11| "" + (let v = [ [ 1 2 3 4 5 6 7 8 ] [1 2 3 4]]; in builtins.deepSeq v v)
+             |      ^
+           12|
+
+       error: cannot coerce a list to a string: [ [ 1 2 3 4 5 6 7 8 ] [ 1 «3 items elided» ] ]

tests/functional/lang/eval-fail-nested-list-items.nix

@@ -0,0 +1,11 @@
+# This reproduces https://github.com/NixOS/nix/issues/10993, for lists
+# $ nix run nix/2.23.1 -- eval --expr '"" + (let v = [ [ 1 2 3 4 5 6 7 8 ] [1 2 3 4]]; in builtins.deepSeq v v)'
+# error:
+#        … while evaluating a path segment
+#          at «string»:1:6:
+#             1| "" + (let v = [ [ 1 2 3 4 5 6 7 8 ] [1 2 3 4]]; in builtins.deepSeq v v)
+#              |      ^
+#
+#        error: cannot coerce a list to a string: [ [ 1 2 3 4 5 6 7 8 ] [ 1 «4294967290 items elided» ] ]
+
+"" + (let v = [ [ 1 2 3 4 5 6 7 8 ] [1 2 3 4]]; in builtins.deepSeq v v)