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-rw-r--r--doc/manual/src/release-notes/rl-next.md2
-rw-r--r--src/libexpr/value-to-json.cc22
-rw-r--r--tests/lang/eval-fail-toJSON.err.exp57
-rw-r--r--tests/lang/eval-fail-toJSON.nix10
4 files changed, 88 insertions, 3 deletions
diff --git a/doc/manual/src/release-notes/rl-next.md b/doc/manual/src/release-notes/rl-next.md
index 065364453..df30ce83d 100644
--- a/doc/manual/src/release-notes/rl-next.md
+++ b/doc/manual/src/release-notes/rl-next.md
@@ -6,3 +6,5 @@
[`builtins.flakeRefToString`](@docroot@/language/builtins.md#builtins-flakeRefToString),
have been added.
These functions are useful for converting between flake references encoded as attribute sets and URLs.
+
+- [`builtins.toJSON`](@docroot@/language/builtins.md#builtins-parseFlakeRef) now prints [--show-trace](@docroot@/command-ref/conf-file.html#conf-show-trace) items for the path in which it finds an evaluation error.
diff --git a/src/libexpr/value-to-json.cc b/src/libexpr/value-to-json.cc
index 4996a5bde..ac3986c87 100644
--- a/src/libexpr/value-to-json.cc
+++ b/src/libexpr/value-to-json.cc
@@ -43,6 +43,7 @@ json printValueAsJSON(EvalState & state, bool strict,
break;
case nNull:
+ // already initialized as null
break;
case nAttrs: {
@@ -59,7 +60,13 @@ json printValueAsJSON(EvalState & state, bool strict,
names.emplace(state.symbols[j.name]);
for (auto & j : names) {
Attr & a(*v.attrs->find(state.symbols.create(j)));
- out[j] = printValueAsJSON(state, strict, *a.value, a.pos, context, copyToStore);
+ try {
+ out[j] = printValueAsJSON(state, strict, *a.value, a.pos, context, copyToStore);
+ } catch (Error & e) {
+ e.addTrace(state.positions[a.pos],
+ hintfmt("while evaluating attribute '%1%'", j));
+ throw;
+ }
}
} else
return printValueAsJSON(state, strict, *i->value, i->pos, context, copyToStore);
@@ -68,8 +75,17 @@ json printValueAsJSON(EvalState & state, bool strict,
case nList: {
out = json::array();
- for (auto elem : v.listItems())
- out.push_back(printValueAsJSON(state, strict, *elem, pos, context, copyToStore));
+ int i = 0;
+ for (auto elem : v.listItems()) {
+ try {
+ out.push_back(printValueAsJSON(state, strict, *elem, pos, context, copyToStore));
+ } catch (Error & e) {
+ e.addTrace({},
+ hintfmt("while evaluating list element at index %1%", i));
+ throw;
+ }
+ i++;
+ }
break;
}
diff --git a/tests/lang/eval-fail-toJSON.err.exp b/tests/lang/eval-fail-toJSON.err.exp
new file mode 100644
index 000000000..4e618c203
--- /dev/null
+++ b/tests/lang/eval-fail-toJSON.err.exp
@@ -0,0 +1,57 @@
+error:
+ … while calling the 'toJSON' builtin
+
+ at /pwd/lang/eval-fail-toJSON.nix:1:1:
+
+ 1| builtins.toJSON {
+ | ^
+ 2| a.b = [
+
+ … while evaluating attribute 'a'
+
+ at /pwd/lang/eval-fail-toJSON.nix:2:3:
+
+ 1| builtins.toJSON {
+ 2| a.b = [
+ | ^
+ 3| true
+
+ … while evaluating attribute 'b'
+
+ at /pwd/lang/eval-fail-toJSON.nix:2:3:
+
+ 1| builtins.toJSON {
+ 2| a.b = [
+ | ^
+ 3| true
+
+ … while evaluating list element at index 3
+
+ … while evaluating attribute 'c'
+
+ at /pwd/lang/eval-fail-toJSON.nix:7:7:
+
+ 6| {
+ 7| c.d = throw "hah no";
+ | ^
+ 8| }
+
+ … while evaluating attribute 'd'
+
+ at /pwd/lang/eval-fail-toJSON.nix:7:7:
+
+ 6| {
+ 7| c.d = throw "hah no";
+ | ^
+ 8| }
+
+ … while calling the 'throw' builtin
+
+ at /pwd/lang/eval-fail-toJSON.nix:7:13:
+
+ 6| {
+ 7| c.d = throw "hah no";
+ | ^
+ 8| }
+
+ error: hah no
diff --git a/tests/lang/eval-fail-toJSON.nix b/tests/lang/eval-fail-toJSON.nix
new file mode 100644
index 000000000..8112e1c1f
--- /dev/null
+++ b/tests/lang/eval-fail-toJSON.nix
@@ -0,0 +1,10 @@
+builtins.toJSON {
+ a.b = [
+ true
+ false
+ "it's a bird"
+ {
+ c.d = throw "hah no";
+ }
+ ];
+}