Location.3o - Man Page

Source code locations (ranges of positions), used in parsetree.


Module   Location


Module Location
: sig end

Source code locations (ranges of positions), used in parsetree.

Warning: this module is unstable and part of Compiler_libs .

type t = Warnings.loc = {
loc_start : Lexing.position ;
loc_end : Lexing.position ;
loc_ghost : bool ;

Note on the use of Lexing.position in this module. If pos_fname = "" , then use !input_name instead. If pos_lnum = -1 , then pos_bol = 0 . Use pos_cnum and re-parse the file to get the line and character numbers. Else all fields are correct.

val none : t

An arbitrary value of type t ; describes an empty ghost range.

val is_none : t -> bool

True for Location.none , false any other location

val in_file : string -> t

Return an empty ghost range located in a given file.

val init : Lexing.lexbuf -> string -> unit

Set the file name and line number of the lexbuf to be the start of the named file.

val curr : Lexing.lexbuf -> t

Get the location of the current token from the lexbuf .

val symbol_rloc : unit -> t

val symbol_gloc : unit -> t

val rhs_loc : int -> t

rhs_loc n returns the location of the symbol at position n , starting at 1, in the current parser rule.

val rhs_interval : int -> int -> t

val get_pos_info : Lexing.position -> string * int * int

file, line, char

type 'a loc = {
txt : 'a ;
loc : t ;

val mknoloc : 'a -> 'a loc

val mkloc : 'a -> t -> 'a loc

Input info

val input_name : string ref

val input_lexbuf : Lexing.lexbuf option ref

val input_phrase_buffer : Buffer.t option ref

Toplevel-specific functions

val echo_eof : unit -> unit

val separate_new_message : Format.formatter -> unit

val reset : unit -> unit

Rewriting path

val rewrite_absolute_path : string -> string

rewrite_absolute_path path rewrites path to honor the BUILD_PATH_PREFIX_MAP variable if it is set. It does not check whether path is absolute or not. The result is as follows:

-If BUILD_PATH_PREFIX_MAP is not set, just return path .

-otherwise, rewrite using the mapping (and if there are no matching prefixes that will just return path ).


val rewrite_find_first_existing : string -> string option

rewrite_find_first_existing path uses a BUILD_PATH_PREFIX_MAP mapping and tries to find a source in mapping that maps to a result that exists in the file system. There are the following return values:

- None , means either

-BUILD_PATH_PREFIX_MAP is not set and path does not exists, or

-no source prefixes of path in the mapping were found,

- Some target , means target exists and either

-BUILD_PATH_PREFIX_MAP is not set and target = path , or

- target is the first file (in priority order) that path mapped to that exists in the file system.

- Not_found raised, means some source prefixes in the map were found that matched path , but none of them existed in the file system. The caller should catch this and issue an appropriate error message.


val rewrite_find_all_existing_dirs : string -> string list

rewrite_find_all_existing_dirs dir accumulates a list of existing directories, dirs , that are the result of mapping a potentially abstract directory, dir , over all the mapping pairs in the BUILD_PATH_PREFIX_MAP environment variable, if any. The list dirs will be in priority order (head as highest priority).

The possible results are:

- [] , means either

-BUILD_PATH_PREFIX_MAP is not set and dir is not an existing directory, or

-if set, then there were no matching prefixes of dir .

- Some dirs , means dirs are the directories found. Either

-BUILD_PATH_PREFIX_MAP is not set and dirs = [dir] , or

-it was set and dirs are the mapped existing directories.

-Not_found raised, means some source prefixes in the map were found that matched dir , but none of mapping results were existing directories (possibly due to misconfiguration). The caller should catch this and issue an appropriate error message.


val absolute_path : string -> string

absolute_path path first makes an absolute path, s from path , prepending the current working directory if path was relative. Then s is rewritten using rewrite_absolute_path . Finally the result is normalized by eliminating instances of '.' or '..' .

Printing locations

val show_filename : string -> string

In -absname mode, return the absolute path for this filename. Otherwise, returns the filename unchanged.

val print_filename : Format.formatter -> string -> unit

val print_loc : Format.formatter -> t -> unit

val print_locs : Format.formatter -> t list -> unit

Toplevel-specific location highlighting

val highlight_terminfo : Lexing.lexbuf -> Format.formatter -> t list -> unit

Reporting errors and warnings

The type of reports and report printers

type msg = (Format.formatter -> unit) loc

val msg : ?loc:t -> ('a, Format.formatter, unit, msg) format4 -> 'a

type report_kind =
| Report_error
| Report_warning of string
| Report_warning_as_error of string
| Report_alert of string
| Report_alert_as_error of string

type report = {
kind : report_kind ;
main : msg ;
sub : msg list ;

type report_printer = {
pp : report_printer -> Format.formatter -> report -> unit ;
pp_report_kind : report_printer -> report -> Format.formatter -> report_kind -> unit ;
pp_main_loc : report_printer -> report -> Format.formatter -> t -> unit ;
pp_main_txt : report_printer -> report -> Format.formatter -> (Format.formatter -> unit) -> unit ;
pp_submsgs : report_printer -> report -> Format.formatter -> msg list -> unit ;
pp_submsg : report_printer -> report -> Format.formatter -> msg -> unit ;
pp_submsg_loc : report_printer -> report -> Format.formatter -> t -> unit ;
pp_submsg_txt : report_printer -> report -> Format.formatter -> (Format.formatter -> unit) -> unit ;

A printer for report s, defined using open-recursion. The goal is to make it easy to define new printers by re-using code from existing ones.

Report printers used in the compiler

val batch_mode_printer : report_printer

val terminfo_toplevel_printer : Lexing.lexbuf -> report_printer

val best_toplevel_printer : unit -> report_printer

Detects the terminal capabilities and selects an adequate printer

Printing a report

val print_report : Format.formatter -> report -> unit

Display an error or warning report.

val report_printer : (unit -> report_printer) ref

Hook for redefining the printer of reports.

The hook is a unit -> report_printer and not simply a report_printer : this is useful so that it can detect the type of the output (a file, a terminal, ...) and select a printer accordingly.

val default_report_printer : unit -> report_printer

Original report printer for use in hooks.

Reporting warnings

Converting a Warnings.t into a report

val report_warning : t -> Warnings.t -> report option

report_warning loc w produces a report for the given warning w , or None if the warning is not to be printed.

val warning_reporter : (t -> Warnings.t -> report option) ref

Hook for intercepting warnings.

val default_warning_reporter : t -> Warnings.t -> report option

Original warning reporter for use in hooks.

Printing warnings

val formatter_for_warnings : Format.formatter ref

val print_warning : t -> Format.formatter -> Warnings.t -> unit

Prints a warning. This is simply the composition of report_warning and print_report .

val prerr_warning : t -> Warnings.t -> unit

Same as print_warning , but uses !formatter_for_warnings as output formatter.

Reporting alerts

Converting an Alert.t into a report

val report_alert : t -> Warnings.alert -> report option

report_alert loc w produces a report for the given alert w , or None if the alert is not to be printed.

val alert_reporter : (t -> Warnings.alert -> report option) ref

Hook for intercepting alerts.

val default_alert_reporter : t -> Warnings.alert -> report option

Original alert reporter for use in hooks.

Printing alerts

val print_alert : t -> Format.formatter -> Warnings.alert -> unit

Prints an alert. This is simply the composition of report_alert and print_report .

val prerr_alert : t -> Warnings.alert -> unit

Same as print_alert , but uses !formatter_for_warnings as output formatter.

val deprecated : ?def:t -> ?use:t -> t -> string -> unit

Prints a deprecation alert.

val alert : ?def:t -> ?use:t -> kind:string -> t -> string -> unit

Prints an arbitrary alert.

val auto_include_alert : string -> unit

Prints an alert that -I +lib has been automatically added to the load path

val deprecated_script_alert : string -> unit

deprecated_script_alert command prints an alert that command foo has been deprecated in favour of command ./foo

Reporting errors

type error = report

An error is a report which report_kind must be Report_error .

val error : ?loc:t -> ?sub:msg list -> string -> error

val errorf : ?loc:t -> ?sub:msg list -> ('a, Format.formatter, unit, error) format4 -> 'a

val error_of_printer : ?loc:t -> ?sub:msg list -> (Format.formatter -> 'a -> unit) -> 'a -> error

val error_of_printer_file : (Format.formatter -> 'a -> unit) -> 'a -> error

Automatically reporting errors for raised exceptions

val register_error_of_exn : (exn -> error option) -> unit

Each compiler module which defines a custom type of exception which can surface as a user-visible error should register a "printer" for this exception using register_error_of_exn . The result of the printer is an error value containing a location, a message, and optionally sub-messages (each of them being located as well).

val error_of_exn : exn -> [ `Already_displayed | `Ok of error ] option

exception Error of error

Raising Error e signals an error e ; the exception will be caught and the error will be printed.

exception Already_displayed_error

Raising Already_displayed_error signals an error which has already been printed. The exception will be caught, but nothing will be printed

val raise_errorf : ?loc:t -> ?sub:msg list -> ('a, Format.formatter, unit, 'b) format4 -> 'a

val report_exception : Format.formatter -> exn -> unit

Reraise the exception if it is unknown.


2024-01-25 OCamldoc OCaml library