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metalint - a metaconfig unit consistency checker


metalint [ -hklsV ] [ -L dir ]


Metalint parses the units and performs some extensive consistency checks, to make sure the
whole set is sound. Due to the relatively huge amount of units available, it is becoming
very difficult to maintain the units manually, and an automated process can be of real
help, although not perfect.

Metalint operates from within your top level package directory and is used to make sure
your own private units are correctly relying on the publicly available units. If you
intensively develop new units, you should run metalint on them before making them publicly


Metalint recognizes the following set of options:

-h Print a short usage description and exit.

-k Keep temporary .MT directory.

-l (not implemented yet) By default, metalint only reports problems related to
your own private units. This switch directs metalint to also report
problems in publicly available units.

-s Silent mode.

-L dir Override default library location. Normally only useful for metaconfig
maintainers to locally check the units being developed instead of the
publicly available ones. The dir specified is the one containing the units
U directory.

-V Print version number and exit.


The following diagnostics may be emitted by metalint:

"(?MAKE) ignoring duplicate dependency listing line."
More than one ?MAKE: line bearing dependencies was found in the unit. There may be
only one such line, although multiple ?MAKE action lines may occur.

"(?MAKE) special unit 'Xxx' should not be listed as made."
A special unit symbol (first letter capitalized) may only be listed as made in the
special unit itself. To suppress this warning in legitimate cases, add a '+' in front
of the offending symbol (note that for non-special units, the '+' in this position
indicates an internal symbol which should not appear in the config.sh file).

"(?MAKE) '+xxx' is listed x times."
A conditional dependency is listed more than once. This is harmless though.

"(?MAKE) 'xxx' is listed x times."
A normal depdendency is listed more than once. Again, an harmless error.

"(?MAKE) 'xxx' listed as both conditional and full dependency."
Symbol is listed as a normal dependency and as a conditional one. Metaconfig will
consider this as being a full dependency, but that may not be what you initially

"(?Y) unknown layout directive 'xxx'."
Layout directives may only be one of top, default or bottom, but case does not
matter. An unknown directive is just ignored and handled as if default had been

"(?S) duplicate description for variable '$xxx'."
Shell symbol is described more than once, and that will produce two entries in the

"(?S) variable '$xxx' is not listed on ?MAKE: line."
The unit describes a shell symbol entry which cannot be used externally since not
listed as a dependency.

"(?S) syntax error in ?S: construct."
Self explainatory.

"(?C) duplicate description for symbol 'XXX'."
C symbol is described more than once, and that will produce two entries for it in the

"(?C) syntax error in ?C: construct."
Self explainatory.

"(?H) symbol 'XXX' was already defined."
Apparently, two ?H: lines are defining the same C symbol.

"(?H) variable '$xxx' not even listed on ?MAKE: line."
A variable is used, but not listed on the dependency line.

"(?H) section was already terminated by '?H:.'."
There can be no more ?H: lines after the first '?H:.' marking the end of that

"(?H) uncommon cpp line should be protected with '?%<:'."
All ?H: lines that are recognized by metaconfig and thus metalint have their
inclusion in config.h automatically protected by a suitable symbol if none is
provided. However, unrecognized lines must be protected with the '?%<:' sequence to
avoid their inclusion should the unit not be loaded in Configure.

"(?H) line should not be listed here but in '?C:'."
Only cpp lines should appear in the ?H: section. If you have a comment to put
regarding the symbol, use ?C:. If you want to comment a particular generation
sequence, put them into ?X: comment so that they don't make it into config.h.

"(?H) constraint 'xxx' is an unknown symbol."
All the leading ?sym: constraints on the ?H: lines should be a valid shell or C
symbol, defined in the unit.

"(?M) syntax error in ?M: construct."
Self explainatory.

"(?M) symbol 'xxx' already listed on a ?M: line in 'yyy'."
A magic definition for symbol xxx is attempted, but another one was already provided
in unit yyy.

"(?V) visible declaration in non-special unit ignored."
Visible declarations (?V: lines) may only appear in special units. Otherwise, they
are meaningless.

"(?V) wanted variable '$xxx' made visible."
A wanted variable (described as a dependency on the ?MAKE: line) cannot be made
visible since that does not make any sense: the unit cannot depend on it and then
advertise it as being locally defined.

"(?V) defined variable '$xxx' made visible."
A defined variable (listed as made on the ?MAKE: line) cannot be made visible, since
it could as well be directly wanted in another unit.

"(?V) variable '$xxx' already made visible by unit yyy."
Inconsistent declaration: two units are making one single symbol visible...

"(?V) variable '$xxx' already read-write visible in yyy."
The variable was already made visible as read-write by another unit.

"(?V) variable '$xxx' already read-only visible in yyy."
The variable was already made visible as read-only by another unit.

"(?W) variable '$xxx' already wanted."
Variable is already wanted, there is no need to explicitly ask for it here.

"(?W) variable '$xxx' also locally defined."
A wanted variable would conflict with a locally defined variable and could result in
getting a garbage value.

"(?W) variable '$xxx' already listed on a ?W: line in 'yyy'."
The variable in the shell symbol section of a ?W: line can only appear in one unit.

"(?F) produced file 'xxx' mutiply declared."
The file is listed more than once on the ?F: line, under the same name. This does
not appear when declaring both a private UU file and a public file with the same
name, for instance.

"(?F) UU file in non-special unit ignored."
Private UU files (i.e. files like the myread script created for later perusal by
Configure) may only be created in special units. Exceptions allowed if the ?F: line
is preceded by a proper ?LINT: hint.

"(?T) temporary symbol '$xxx' multiply declared."
Self explainatory.

"directive should come after ?MAKE declarations."
The directive listed between () at the beginning of this message should really come
after the ?MAKE: lines. You must reorder the unit or metalint will not be able to
properly diagnose problems.

"control sequence '?XXX:' ignored within body."
Attempt to use a control line other than ?X: or ?LINT: in the unit body, which should
be only shell code

"variable '$xxx' is changed."
A variable listed as wanted in the dependency line is changed. Such a variable should
be read-only for the unit. Use the change lint hint to suppress this message in
pathological cases.

"no ?MAKE: line describing dependencies."
Every unit should have a dependency line, or it will be silently ignored by
metaconfig. This message is suppressed by a ?LINT: empty hint.

"first body line should be a general ': description'."
The very first shell line of the unit that will be added to the generated Configure
script should hold a description of the unit's purpose, on a ':' line. There must be
a space after the ':', since it is interpreted by the shell, and the description
should avoid meta-characters like '(' or '>' unless the whole string is quoted. This
message is suppressed by a ?LINT: nocomment hint.

"missing space after ':' to make it a comment."
A line starting by ':' is interpreted by the shell but will be ignored. There must
be a space after the ':' though, or the shell will try to execute an unknown

"found unquoted meta-character > on comment line."
A line starting by ':' is interpreted by the shell but will be ignored. This means
that meaningful meta-characters such as '(' or '>' must be quoted or escaped with a
leading backslash.

"found dangling quote on ':' comment line."
An unclosed single or double quote was spotted on a ':' comment line. Since those
lines are interpreted by the shell, albeit ignored, all quotes must match perfectly.

"not ending with a blank line."
Since all units are gathered together to form one big script, it is recommended
(hence enforced by metalint) that every unit file end with an empty line.

"last line not ending with a new-line character."
This is merely intended to users whose editor does not always append a new-line at
the end of text files. Should not happen when you use vi.

"symbol '$xxx' was not described."
The shell symbol defined by this unit was not documented. Use the describe lint hint
to suppress this message.

"C symbol 'XXX' was not described."
The C symbol defined by this unit was not documented. Use the known lint hint to
suppress this message.

"C symbol 'XXX' was not defined by any ?H: line."
A C symbol was advertised by never defined, hence it cannot appear in the config.h
file and is therefore useless...

"variable '$xxx' should have been set."
A variable listed on the make line as made by the unit was not set by the shell code
body. Use the set lint hint to suppress this message in pathological cases.

"unused dependency variable '$xxx'."
Apparently no usage is made from a shell variable. Use the change or use lint hints
(depending on the situation) to suppress this message.

"unused conditional variable '$xxx'.
Apparently no usage is made from this conditional dependency. The change or use lint
hints can be used to suppress this message.

"unused temporary variable '$xxx'."
A variable declared as temporary in a ?T: line is not used. The use lint hint will
fool metalint into thinking it's indeed used.

"unknown control sequence '?XXX:'."
Attempt to use an unknown control sequence.

"unknown LINT request 'false' ignored."
An unknown ?LINT: tag was used. All such tags must be spelled out in lowercase.

"symbol '$xxx' has no default value."
A symbol used as a conditional dependency in some unit has no default value set by a
?D: line.

"stale ?MAKE: dependency 'xxx'."
Unit lists a symbol as a dependency, but that symbol is otherwise unknown, i.e.
never appears as made by any other unit.

"symbol '$xxx' missing from ?MAKE."
A symbol used or defined was not listed as a dependency in the ?MAKE: line.

"missing xxx from ?MAKE for visible '$yyy'."
A symbol defined as visible by a special unit is used, but that special unit is not
part of the dependency line.

"stale ?M: dependency 'xxx'."
Magic line lists a C symbol as a dependency but that symbol is not known by any unit.

"unknown symbol '$xxx'."
I have no idea about what this symbol is. If the variable is externally define, this
warning can be suppresed via a proper ?LINT: extern.

"read-only symbol '$xxx' is set."
A symbol that should be read-only is set by the unit's shell code body.

"obsolete symbol 'xxx' is used."
An obsolete symbol is used in the unit's shell code.

"undeclared symbol '$xxx' is set."
The unit tries to set a shell variable which has not been otherwise declared as made
or as a temporary variable, or whatever.

"unclosed ?H: section."
The ?H: section was not terminated by a single '?H:.' line before the body of the
unit or the start of another ?C: section.

"C symbol 'xxx' is defined in the following units:"
The C symbol is defined in more that one unit. Offending units are listed.

"Shell symbol 'xxx' is defined in the following units:"
A shell symbol is defined in more than one unit. Offending units folllow.

"Shell symbol 'xxx' is altogether:"
A shell symbol is defined by some units, obsoleted by others and used as a temporary.

"Shell symbol 'xxx' is both defined and obsoleted:"
Self explainatory.

"Shell symbol 'xxx' is both defined and used as temporary:"
Self explainatory.

"Shell symbol 'xxx' obsoleted also used as temporary:"
Self explainatory.

"definition of '$xxx' not closed by '?S:.'."
Self explainatory.

"definition of 'XXX' not closed by '?C:.'."
Self explainatory.

"magic definition of 'xxx' not closed by '?M:.'."
Self explainatory.

"variable '$xxx' is defined externally."
A variable defined externally (i.e. in another unit) is used, without proper
dependency information. Use the extern lint hint to suppress this message.

"file 'xxx' was not created."
A file listed as a private UU file is not created by the special unit. Creation is
detected by seing an explicit shell redirection to the file, not by an implicit
creation (such as a C compilation would for instance). All special units should
create only shell scripts explicitly anyway so this message cannot be suppressed via
a lint hint.

"local file 'xxx' may override the one set by 'unit.U'."
You are attempting to create a local file, but the special unit creates one bearing
the exact same name and should it be loaded before within Configure, you would
override that file. Change the name of your local file.

"unused temporary file 'xxx'.
The file was declared on the ?F: line but does not appear to be used anywhere.

"mis-used temporary file 'xxx'.
A local temporary file has been declared on the ?F: line and is used in a way that
may not be the proper one. Indeed, all such local files should be called with an
explicit relative path, to avoid PATH lookups which could get you another file.

"you might not always get file 'xxx' from 'unit.U'."
You seem to be calling the specified file, but not by using an explicit relative
pathname. Relying on the PATH to find this file is not safe. To fix this problem,
call your file using somthing like ./xxx.

"missing Unit from ?MAKE for private file 'xxx'."
You are using a private UU file without listing the special unit that produces it in
your dependency line. Add the unit to your dependency list.

"unknown private file 'xxx'."
The file does not appear on any ?F: line; however it should.

"File 'xxx' is defined in the following units:"
The listed units cannot seem to agree on who is defining the file.

"empty here-document name discouraged."
You should refrain from using empty names for here documents, as metalint will not
monitor those.

"unclosed here-document xxx started line x."
The opened here-document at line x was never closed in this unit. This generally
mean that when the unit is used, the generated script will not work!

"spurious 'LINT xxx' directive."
You have inserted a ?LINT: directive that is not used to shut-up warnings.

"Cycle found for:"
There is a dependency cycle found for the symbols listed. Only the symbols involved
in the cycle are listed.

"Cycle involves:"
An exerpt of the dependencies where the cycle was found is listed. This may involve
far more symbols than the previous message, because metalint actually rescans the
rules to emphasize the cycle and stops whenever it has found one, i.e. it does not
try to minimize it (the cycle is found using another algorithm, which unfortunately
cannot spit it out but only say for sure there is one).


Metalint uses the following control lines, which are otherwise ignored by metaconfig:

?V:read-only symbols:read-write symbols
This line should be used only in special units. It lists all the shell variable
defined by the unit which should not be used directly as dependencies by other units:
they must include this special unit in their dependency list if they make use of any
of the symbols described here. Those can be viewed as exported symbols which you
inherit from when depending from the unit. Symbols may be exported read-only or

?F:files created
This line serves two purposes: it is a metalint hint, and also a placeholder for
future jmake use. It must list three kind of files: the temporary one which are
created for a test, the private UU ones created in the UU directory for later
perusal, and the public ones left in the root directory of the package. Temporary
files must be listed with a preceding '!' character (meaning "no! they're not re-used
later!"), private UU files should be preceded by a './' (meaning: to use them, say
./file, not just file), and public ones should be named as-is.

?T:shell temporaries
This line should list all the shell variables used as temporaries within the unit's
body. This line should be kept accurate, and prevents you from writing a unit
defining a symbol which would be used as a scratch variable in another unit...

?LINT:keyword symbol_list
Specifies a lint hint. The following keywords are available:

change shell variable ok to be changed
create persistent file ok to be created by non-special unit
define shell variables listed are defined in this unit
describe listed shell variables are described by ?S:
extern variable known to be externally defined
empty unit file is empty and kept only as a placeholder.
known listed C variables are described
nocomment unit file is special and may miss a leading ': description' line.
nothere listed names are not here documents (e.g. "1 << foo" in a C
set listed variables are set
use variables listed are used by this unit
unclosed listed names of here-documents are not closed in this unit
usefile listed file is used (do not prepend name with '!' for temporary


Harlan Stenn <[email protected]> wrote the first version, based on Larry Wall's
metaconfig from dist 2.0.
Raphael Manfredi <[email protected]> rewrote it from scratch for 3.0 with a few

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