lix/src/libexpr/print-ambiguous.cc
eldritch horrors 87e6ac5eb7 Merge pull request #9753 from 9999years/print-value-on-type-error
Print the value in `value is X while a Y is expected` error

(cherry picked from commit 5f72a97092da6af28a7d2b2a50d74e9d34fae7e1)
Change-Id: Idb4bc903ae59a0f5b6fb3b1da4d47970fe0a6efe
2024-03-09 00:05:41 -07:00

101 lines
2.7 KiB
C++

#include "print-ambiguous.hh"
#include "print.hh"
#include "eval.hh"
namespace nix {
// See: https://github.com/NixOS/nix/issues/9730
void printAmbiguous(
Value &v,
const SymbolTable &symbols,
std::ostream &str,
std::set<const void *> *seen,
int depth)
{
checkInterrupt();
if (depth <= 0) {
str << "«too deep»";
return;
}
switch (v.type()) {
case nInt:
str << v.integer;
break;
case nBool:
printLiteralBool(str, v.boolean);
break;
case nString:
printLiteralString(str, v.string.s);
break;
case nPath:
str << v.path().to_string(); // !!! escaping?
break;
case nNull:
str << "null";
break;
case nAttrs: {
if (seen && !v.attrs->empty() && !seen->insert(v.attrs).second)
str << "«repeated»";
else {
str << "{ ";
for (auto & i : v.attrs->lexicographicOrder(symbols)) {
str << symbols[i->name] << " = ";
printAmbiguous(*i->value, symbols, str, seen, depth - 1);
str << "; ";
}
str << "}";
}
break;
}
case nList:
if (seen && v.listSize() && !seen->insert(v.listElems()).second)
str << "«repeated»";
else {
str << "[ ";
for (auto v2 : v.listItems()) {
if (v2)
printAmbiguous(*v2, symbols, str, seen, depth - 1);
else
str << "(nullptr)";
str << " ";
}
str << "]";
}
break;
case nThunk:
if (!v.isBlackhole()) {
str << "<CODE>";
} else {
// 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;
case nFunction:
if (v.isLambda()) {
str << "<LAMBDA>";
} else if (v.isPrimOp()) {
str << "<PRIMOP>";
} else if (v.isPrimOpApp()) {
str << "<PRIMOP-APP>";
}
break;
case nExternal:
str << *v.external;
break;
case nFloat:
str << v.fpoint;
break;
default:
printError("Nix evaluator internal error: printAmbiguous: invalid value type");
abort();
}
}
}