piegames
49d61b2e4b
They are like experimental features, but opt-in instead of opt-out. They will allow us to gracefully remove language features. See #437 Change-Id: I9ca04cc48e6926750c4d622c2b229b25cc142c42
109 lines
3.2 KiB
C++
109 lines
3.2 KiB
C++
#include "deprecated-features.hh"
|
|
// Required for instances of to_json and from_json for DeprecatedFeature
|
|
#include "deprecated-features-json.hh"
|
|
#include "strings.hh"
|
|
|
|
#include "nlohmann/json.hpp"
|
|
|
|
namespace nix {
|
|
|
|
struct DeprecatedFeatureDetails
|
|
{
|
|
DeprecatedFeature tag;
|
|
std::string_view name;
|
|
std::string_view description;
|
|
};
|
|
|
|
/**
|
|
* If two different PRs both add a deprecated feature, and we just
|
|
* used a number for this, we *woudln't* get merge conflict and the
|
|
* counter will be incremented once instead of twice, causing a build
|
|
* failure.
|
|
*
|
|
* By instead defining this instead as 1 + the bottom deprecated
|
|
* feature, we either have no issue at all if few features are not added
|
|
* at the end of the list, or a proper merge conflict if they are.
|
|
*/
|
|
constexpr size_t numDepFeatures = 0;
|
|
|
|
constexpr std::array<DeprecatedFeatureDetails, numDepFeatures> depFeatureDetails = {{
|
|
}};
|
|
|
|
static_assert(
|
|
[]() constexpr {
|
|
for (auto [index, feature] : enumerate(depFeatureDetails))
|
|
if (index != (size_t)feature.tag)
|
|
return false;
|
|
return true;
|
|
}(),
|
|
"array order does not match enum tag order");
|
|
|
|
const std::optional<DeprecatedFeature> parseDeprecatedFeature(const std::string_view & name)
|
|
{
|
|
using ReverseDepMap = std::map<std::string_view, DeprecatedFeature>;
|
|
|
|
static std::unique_ptr<ReverseDepMap> reverseDepMap = []() {
|
|
auto reverseDepMap = std::make_unique<ReverseDepMap>();
|
|
for (auto & depFeature : depFeatureDetails)
|
|
(*reverseDepMap)[depFeature.name] = depFeature.tag;
|
|
return reverseDepMap;
|
|
}();
|
|
|
|
if (auto feature = get(*reverseDepMap, name))
|
|
return *feature;
|
|
else
|
|
return std::nullopt;
|
|
}
|
|
|
|
std::string_view showDeprecatedFeature(const DeprecatedFeature tag)
|
|
{
|
|
assert((size_t)tag < depFeatureDetails.size());
|
|
return depFeatureDetails[(size_t)tag].name;
|
|
}
|
|
|
|
nlohmann::json documentDeprecatedFeatures()
|
|
{
|
|
StringMap res;
|
|
for (auto & depFeature : depFeatureDetails)
|
|
res[std::string { depFeature.name }] =
|
|
trim(stripIndentation(depFeature.description));
|
|
return (nlohmann::json) res;
|
|
}
|
|
|
|
std::set<DeprecatedFeature> parseDeprecatedFeatures(const std::set<std::string> & rawFeatures)
|
|
{
|
|
std::set<DeprecatedFeature> res;
|
|
for (auto & rawFeature : rawFeatures)
|
|
if (auto feature = parseDeprecatedFeature(rawFeature))
|
|
res.insert(*feature);
|
|
return res;
|
|
}
|
|
|
|
MissingDeprecatedFeature::MissingDeprecatedFeature(DeprecatedFeature feature)
|
|
: Error("Lix feature '%1%' is deprecated and should not be used anymore; use '--extra-deprecated-features %1%' to disable this error", showDeprecatedFeature(feature))
|
|
, missingFeature(feature)
|
|
{}
|
|
|
|
std::ostream & operator <<(std::ostream & str, const DeprecatedFeature & feature)
|
|
{
|
|
return str << showDeprecatedFeature(feature);
|
|
}
|
|
|
|
void to_json(nlohmann::json & j, const DeprecatedFeature & feature)
|
|
{
|
|
j = showDeprecatedFeature(feature);
|
|
}
|
|
|
|
void from_json(const nlohmann::json & j, DeprecatedFeature & feature)
|
|
{
|
|
const std::string input = j;
|
|
const auto parsed = parseDeprecatedFeature(input);
|
|
|
|
if (parsed.has_value())
|
|
feature = *parsed;
|
|
else
|
|
throw Error("Unknown deprecated feature '%s' in JSON input", input);
|
|
}
|
|
|
|
}
|