error.hh File Reference

This file defines two main structs/classes used in nix error handling. More...

#include "lix/libutil/json-fwd.hh"
#include "lix/libutil/suggestions.hh"
#include "lix/libutil/fmt.hh"
#include <cstring>
#include <list>
#include <memory>
#include <optional>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <system_error>
#include <type_traits>

Include dependency graph for error.hh:

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Classes
struct	nix::json::is_integral_enum< Verbosity >
struct	nix::LinesOfCode
struct	nix::Trace
struct	nix::ErrorInfo
class	nix::BaseError
class	nix::SysError

Macros
#define	MakeError(newClass, superClass)

Enumerations
enum	Verbosity {   lvlError = 0 , lvlWarn , lvlNotice , lvlInfo ,   lvlTalkative , lvlChatty , lvlDebug , lvlVomit }
enum struct	nix::TracePrint { Default , Always }
enum struct	TraceSize

Functions
Verbosity	nix::verbosityFromIntClamped (int val)
void	nix::printCodeLines (std::ostream &out, const std::string &prefix, const Pos &errPos, const LinesOfCode &loc)
bool	nix::operator< (const Trace &lhs, const Trace &rhs)
bool	nix::operator> (const Trace &lhs, const Trace &rhs)
bool	nix::operator<= (const Trace &lhs, const Trace &rhs)
bool	nix::operator>= (const Trace &lhs, const Trace &rhs)
std::ostream &	nix::showErrorInfo (std::ostream &out, const ErrorInfo &einfo, bool showTrace)
	nix::MakeError (Error, BaseError)
	nix::MakeError (UsageError, Error)
	nix::MakeError (UnimplementedError, Error)
void	nix::ignoreExceptionInDestructor (Verbosity lvl)
void	nix::ignoreExceptionExceptInterrupt (Verbosity lvl)

Detailed Description

This file defines two main structs/classes used in nix error handling.

ErrorInfo provides a standard payload of error information, with conversion to string happening in the logger rather than at the call site.

BaseError is the ancestor of nix specific exceptions (and Interrupted), and contains an ErrorInfo.

ErrorInfo structs are sent to the logger as part of an exception, or directly with the logError or logWarning macros. See libutil/tests/logging.cc for usage examples.

Macro Definition Documentation

MakeError

#define MakeError	(		newClass,
			superClass )

Value:

    /* NOLINTNEXTLINE(bugprone-macro-parentheses) */    \
    class newClass : public superClass                  \
    {                                                   \
    public:                                             \
        using superClass::superClass;                   \
    }

Enumeration Type Documentation

TracePrint

enum struct nix::TracePrint

strong

Enumerator
Default	The default behavior; always printed when --show-trace is set
Always	Always printed. Produced by builtins.addErrorContext

Function Documentation

ignoreExceptionExceptInterrupt()

void nix::ignoreExceptionExceptInterrupt

(

Verbosity

lvl = lvlError

)

Not destructor-safe. Print an error message, then ignore the exception. If the exception is an Interrupted exception, rethrow it.

This may be used in a few places where Interrupt can't happen, but that's ok.

ignoreExceptionInDestructor()

void nix::ignoreExceptionInDestructor

(

Verbosity

lvl = lvlError

)

Exception handling in destructors: print an error message, then ignore the exception.

If you're not in a destructor, you usually want to use ignoreExceptionExceptInterrupt().

This function might also be used in callbacks whose caller may not handle exceptions, but ideally we propagate the exception using an exception_ptr in such cases. See e.g. PackBuilderContext

operator<()

bool nix::operator< ( const Trace & lhs, const Trace & rhs )

inline

An arbitrarily defined value comparison for the purpose of using traces in the key of a sorted container.