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nix/src/libstore/build/entry-points.cc
Rebecca Turner c6a89c1a16
libexpr: Support structured error classes
While preparing PRs like #9753, I've had to change error messages in
dozens of code paths. It would be nice if instead of

    EvalError("expected 'boolean' but found '%1%'", showType(v))

we could write

    TypeError(v, "boolean")

or similar. Then, changing the error message could be a mechanical
refactor with the compiler pointing out places the constructor needs to
be changed, rather than the error-prone process of grepping through the
codebase. Structured errors would also help prevent the "same" error
from having multiple slightly different messages, and could be a first
step towards error codes / an error index.

This PR reworks the exception infrastructure in `libexpr` to
support exception types with different constructor signatures than
`BaseError`. Actually refactoring the exceptions to use structured data
will come in a future PR (this one is big enough already, as it has to
touch every exception in `libexpr`).

The core design is in `eval-error.hh`. Generally, errors like this:

    state.error("'%s' is not a string", getAttrPathStr())
      .debugThrow<TypeError>()

are transformed like this:

    state.error<TypeError>("'%s' is not a string", getAttrPathStr())
      .debugThrow()

The type annotation has moved from `ErrorBuilder::debugThrow` to
`EvalState::error`.
2024-02-01 16:39:38 -08:00

140 lines
4.1 KiB
C++

#include "worker.hh"
#include "substitution-goal.hh"
#include "derivation-goal.hh"
#include "local-store.hh"
namespace nix {
void Store::buildPaths(const std::vector<DerivedPath> & reqs, BuildMode buildMode, std::shared_ptr<Store> evalStore)
{
Worker worker(*this, evalStore ? *evalStore : *this);
Goals goals;
for (auto & br : reqs)
goals.insert(worker.makeGoal(br, buildMode));
worker.run(goals);
StringSet failed;
std::optional<Error> ex;
for (auto & i : goals) {
if (i->ex) {
if (ex)
logError(i->ex->info());
else
ex = std::move(i->ex);
}
if (i->exitCode != Goal::ecSuccess) {
if (auto i2 = dynamic_cast<DerivationGoal *>(i.get()))
failed.insert(printStorePath(i2->drvPath));
else if (auto i2 = dynamic_cast<PathSubstitutionGoal *>(i.get()))
failed.insert(printStorePath(i2->storePath));
}
}
if (failed.size() == 1 && ex) {
ex->withExitStatus(worker.failingExitStatus());
throw std::move(*ex);
} else if (!failed.empty()) {
if (ex) logError(ex->info());
throw Error(worker.failingExitStatus(), "build of %s failed", concatStringsSep(", ", quoteStrings(failed)));
}
}
std::vector<KeyedBuildResult> Store::buildPathsWithResults(
const std::vector<DerivedPath> & reqs,
BuildMode buildMode,
std::shared_ptr<Store> evalStore)
{
Worker worker(*this, evalStore ? *evalStore : *this);
Goals goals;
std::vector<std::pair<const DerivedPath &, GoalPtr>> state;
for (const auto & req : reqs) {
auto goal = worker.makeGoal(req, buildMode);
goals.insert(goal);
state.push_back({req, goal});
}
worker.run(goals);
std::vector<KeyedBuildResult> results;
for (auto & [req, goalPtr] : state)
results.emplace_back(KeyedBuildResult {
goalPtr->getBuildResult(req),
/* .path = */ req,
});
return results;
}
BuildResult Store::buildDerivation(const StorePath & drvPath, const BasicDerivation & drv,
BuildMode buildMode)
{
Worker worker(*this, *this);
auto goal = worker.makeBasicDerivationGoal(drvPath, drv, OutputsSpec::All {}, buildMode);
try {
worker.run(Goals{goal});
return goal->getBuildResult(DerivedPath::Built {
.drvPath = makeConstantStorePathRef(drvPath),
.outputs = OutputsSpec::All {},
});
} catch (Error & e) {
return BuildResult {
.status = BuildResult::MiscFailure,
.errorMsg = e.msg(),
};
};
}
void Store::ensurePath(const StorePath & path)
{
/* If the path is already valid, we're done. */
if (isValidPath(path)) return;
Worker worker(*this, *this);
GoalPtr goal = worker.makePathSubstitutionGoal(path);
Goals goals = {goal};
worker.run(goals);
if (goal->exitCode != Goal::ecSuccess) {
if (goal->ex) {
goal->ex->withExitStatus(worker.failingExitStatus());
throw std::move(*goal->ex);
} else
throw Error(worker.failingExitStatus(), "path '%s' does not exist and cannot be created", printStorePath(path));
}
}
void Store::repairPath(const StorePath & path)
{
Worker worker(*this, *this);
GoalPtr goal = worker.makePathSubstitutionGoal(path, Repair);
Goals goals = {goal};
worker.run(goals);
if (goal->exitCode != Goal::ecSuccess) {
/* Since substituting the path didn't work, if we have a valid
deriver, then rebuild the deriver. */
auto info = queryPathInfo(path);
if (info->deriver && isValidPath(*info->deriver)) {
goals.clear();
goals.insert(worker.makeGoal(DerivedPath::Built {
.drvPath = makeConstantStorePathRef(*info->deriver),
// FIXME: Should just build the specific output we need.
.outputs = OutputsSpec::All { },
}, bmRepair));
worker.run(goals);
} else
throw Error(worker.failingExitStatus(), "cannot repair path '%s'", printStorePath(path));
}
}
}