Merge pull request #10994 from hercules-ci/fix-value-print-elided

Fix underflow in `printAttrs`, `printList`
NixOS · Jun 30, 2024 · dc538ad · dc538ad
2 parents 32e6cc6 + b2c7f09
commit dc538ad
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Showing 4 changed files with 38 additions and 11 deletions.
diff --git a/src/libexpr/print.cc b/src/libexpr/print.cc
@@ -163,8 +163,8 @@ class Printer
     EvalState & state;
     PrintOptions options;
     std::optional<ValuesSeen> seen;
-    size_t attrsPrinted = 0;
-    size_t listItemsPrinted = 0;
+    size_t totalAttrsPrinted = 0;
+    size_t totalListItemsPrinted = 0;
     std::string indent;
 
     void increaseIndent()
@@ -345,19 +345,22 @@ class Printer
 
             auto prettyPrint = shouldPrettyPrintAttrs(sorted);
 
+            size_t currentAttrsPrinted = 0;
+
             for (auto & i : sorted) {
                 printSpace(prettyPrint);
 
-                if (attrsPrinted >= options.maxAttrs) {
-                    printElided(sorted.size() - attrsPrinted, "attribute", "attributes");
+                if (totalAttrsPrinted >= options.maxAttrs) {
+                    printElided(sorted.size() - currentAttrsPrinted, "attribute", "attributes");
                     break;
                 }
 
                 printAttributeName(output, i.first);
                 output << " = ";
                 print(*i.second, depth + 1);
                 output << ";";
-                attrsPrinted++;
+                totalAttrsPrinted++;
+                currentAttrsPrinted++;
             }
 
             decreaseIndent();
@@ -402,11 +405,14 @@ class Printer
             output << "[";
             auto listItems = v.listItems();
             auto prettyPrint = shouldPrettyPrintList(listItems);
+
+            size_t currentListItemsPrinted = 0;
+
             for (auto elem : listItems) {
                 printSpace(prettyPrint);
 
-                if (listItemsPrinted >= options.maxListItems) {
-                    printElided(listItems.size() - listItemsPrinted, "item", "items");
+                if (totalListItemsPrinted >= options.maxListItems) {
+                    printElided(listItems.size() - currentListItemsPrinted, "item", "items");
                     break;
                 }
 
@@ -415,7 +421,8 @@ class Printer
                 } else {
                     printNullptr();
                 }
-                listItemsPrinted++;
+                totalListItemsPrinted++;
+                currentListItemsPrinted++;
             }
 
             decreaseIndent();
@@ -588,8 +595,8 @@ class Printer
 
     void print(Value & v)
     {
-        attrsPrinted = 0;
-        listItemsPrinted = 0;
+        totalAttrsPrinted = 0;
+        totalListItemsPrinted = 0;
         indent.clear();
 
         if (options.trackRepeated) {

diff --git a/tests/functional/lang/eval-fail-bad-string-interpolation-4.err.exp b/tests/functional/lang/eval-fail-bad-string-interpolation-4.err.exp
@@ -6,4 +6,4 @@ error:
              |   ^
            10|
 
-       error: cannot coerce a set to a string: { a = { a = { a = { a = "ha"; b = "ha"; c = "ha"; d = "ha"; e = "ha"; f = "ha"; g = "ha"; h = "ha"; j = "ha"; }; «4294967295 attributes elided» }; «4294967294 attributes elided» }; «4294967293 attributes elided» }
+       error: cannot coerce a set to a string: { a = { a = { a = { a = "ha"; b = "ha"; c = "ha"; d = "ha"; e = "ha"; f = "ha"; g = "ha"; h = "ha"; j = "ha"; }; «8 attributes elided» }; «8 attributes elided» }; «8 attributes elided» }
diff --git a/tests/functional/lang/eval-fail-nested-list-items.err.exp b/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» ] ]
diff --git a/tests/functional/lang/eval-fail-nested-list-items.nix b/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)