diff options
| -rw-r--r-- | src/libexpr/eval.cc | 10 | ||||
| -rw-r--r-- | tests/lang.sh | 7 |
2 files changed, 17 insertions, 0 deletions
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc index 584bbc879..22337a3ff 100644 --- a/src/libexpr/eval.cc +++ b/src/libexpr/eval.cc @@ -173,7 +173,17 @@ void Value::print(const SymbolTable & symbols, std::ostream & str, case tFloat: str << fpoint; break; + case tBlackhole: + // Although we know for sure that it's going to be an infinite recursion + // when this value is accessed _in the current context_, it's likely + // that the user will misinterpret a simpler «infinite recursion» output + // as a definitive statement about the value, while in fact it may be + // a valid value after `builtins.trace` and perhaps some other steps + // have completed. + str << "«potential infinite recursion»"; + break; default: + printError("Nix evaluator internal error: Value::print(): invalid value type %1%", internalType); abort(); } } diff --git a/tests/lang.sh b/tests/lang.sh index cdb4174eb..8170cb39d 100644 --- a/tests/lang.sh +++ b/tests/lang.sh @@ -5,12 +5,19 @@ export NIX_REMOTE=dummy:// export NIX_STORE_DIR=/nix/store nix-instantiate --eval -E 'builtins.trace "Hello" 123' 2>&1 | grepQuiet Hello +nix-instantiate --eval -E 'builtins.trace "Hello" 123' 2>/dev/null | grepQuiet 123 nix-instantiate --eval -E 'builtins.addErrorContext "Hello" 123' 2>&1 nix-instantiate --trace-verbose --eval -E 'builtins.traceVerbose "Hello" 123' 2>&1 | grepQuiet Hello nix-instantiate --eval -E 'builtins.traceVerbose "Hello" 123' 2>&1 | grepQuietInverse Hello nix-instantiate --show-trace --eval -E 'builtins.addErrorContext "Hello" 123' 2>&1 | grepQuietInverse Hello expectStderr 1 nix-instantiate --show-trace --eval -E 'builtins.addErrorContext "Hello" (throw "Foo")' | grepQuiet Hello +nix-instantiate --eval -E 'let x = builtins.trace { x = x; } true; in x' \ + 2>&1 | grepQuiet -E 'trace: { x = «potential infinite recursion»; }' + +nix-instantiate --eval -E 'let x = { repeating = x; tracing = builtins.trace x true; }; in x.tracing'\ + 2>&1 | grepQuiet -F 'trace: { repeating = «repeated»; tracing = «potential infinite recursion»; }' + set +x fail=0 |