Split -Wstyle into -Wstyle and the even lower -Wbase, and add

-Wopenbsd and -Wnetbsd to check conventions for the base system of
a specific operating system.  Mark operating system specific messages
with "(OpenBSD)" at the end.

Please use just "-Tlint" to check base system manuals (defaulting
to -Wall, which is now -Wbase), but prefer "-Tlint -Wstyle" for the
manuals of portable software projects you maintain that are not
part of OpenBSD base, to avoid bogus recommendations about base
system conventions that do not apply.

Issue originally reported by semarie@, solution using
an idea from tedu@, discussed with jmc@ and jca@.

1 files changed, 69 insertions, 28 deletions

diff --git a/mandoc.1 b/mandoc.1
index ac49d4ab..11ac4ac3 100644
--- a/mandoc.1
+++ b/mandoc.1
@@ -75,11 +75,6 @@ and for the
 .Xr man 7
 .Ic \&TH
 macro.
-This can also be used to perform style checks according to the
-conventions of one operating system while running on a different
-operating system; see
-.Sx Style messages
-for details.
 .It Fl K Ar encoding
 Specify the input encoding.
 The supported
@@ -151,14 +146,33 @@ to be reported on the standard error output and to affect the exit status.
 The
 .Ar level
 can be
+.Cm base ,
 .Cm style ,
 .Cm warning ,
 .Cm error ,
 or
-.Cm unsupp ;
+.Cm unsupp .
+The
+.Cm base
+level automatically derives the operating system from the contents of the
+.Ic \&Os
+macro, from the
+.Fl Ios
+command line option, or from the
+.Xr uname 3
+return value.
+The levels
+.Cm openbsd
+and
+.Cm netbsd
+are variants of
+.Cm base
+that bypass autodetection and request validation of base system
+conventions for a particular operating system.
+The level
 .Cm all
 is an alias for
-.Cm style .
+.Cm base .
 By default,
 .Nm
 is silent.
@@ -224,7 +238,7 @@ See
 .It Fl T Cm lint
 Parse only: produce no output.
 Implies
-.Fl W Cm style .
+.Fl W Cm all .
 .It Fl T Cm locale
 Encode output using the current locale.
 This is the default.
@@ -596,19 +610,23 @@ option:
 .Pp
 .Bl -tag -width Ds -compact
 .It 0
-No style suggestions, warnings or errors occurred, or those that
-did were ignored because they were lower than the requested
+No base system convention violations, style suggestions, warnings,
+or errors occurred, or those that did were ignored because they
+were lower than the requested
 .Ar level .
 .It 1
-At least one style suggestion occurred, but no warning or error, and
+At least one base system convention violation or style suggestion
+occurred, but no warning or error, and
+.Fl W Cm base
+or
 .Fl W Cm style
 was specified.
 .It 2
 At least one warning occurred, but no error, and
 .Fl W Cm warning
-or
-.Fl W Cm style
-was specified.
+or a lower
+.Ar level
+was requested.
 .It 3
 At least one parsing error occurred,
 but no unsupported feature was encountered, and
@@ -636,7 +654,7 @@ to exit at once, possibly in the middle of parsing or formatting a file.
 Note that selecting
 .Fl T Cm lint
 output mode implies
-.Fl W Cm style .
+.Fl W Cm all .
 .Sh EXAMPLES
 To page manuals to the terminal:
 .Pp
@@ -669,12 +687,19 @@ parser:
 Messages displayed by
 .Nm
 follow this format:
-.Pp
-.D1 Nm Ns : Ar file : Ns Ar line : Ns Ar column : level : message : macro args
+.Bd -ragged -offset indent
+.Nm Ns :
+.Ar file : Ns Ar line : Ns Ar column : level : message : macro args
+.Pq Ar os
+.Ed
 .Pp
 Line and column numbers start at 1.
 Both are omitted for messages referring to an input file as a whole.
 Macro names and arguments are omitted where meaningless.
+The
+.Ar os
+operating system specifier is omitted for messages that are relevant
+for all operating systems.
 Fatal messages about invalid command line arguments
 or operating system errors, for example when memory is exhausted,
 may also omit the
@@ -732,9 +757,15 @@ so it may occasionally issue bogus suggestions.
 Please use your good judgement to decide whether any particular
 .Cm style
 suggestion really justifies a change to the input file.
+.It Cm base
+A convertion used in the base system of a specific operating system
+is not adhered to.
+These are not markup mistakes, and neither the quality of formatting
+nor portability are in danger.
 .El
 .Pp
 Messages of the
+.Cm base ,
 .Cm style ,
 .Cm warning ,
 .Cm error ,
@@ -746,9 +777,15 @@ are hidden unless their level, or a lower level, is requested using a
 option or
 .Fl T Cm lint
 output mode.
-.Ss Style messages
-As indicated below, some style checks are only performed if a
-specific operating system name occurs in the arguments of the
+.Pp
+As indicated below, all
+.Cm base
+and some
+.Cm style
+checks are only performed if a specific operating system name occurs
+in the arguments of the
+.Fl W
+command line option, of the
 .Ic \&Os
 macro, of the
 .Fl Ios
@@ -756,6 +793,7 @@ command line option, or, if neither are present, in the return value
 of the
 .Xr uname 3
 function.
+.Ss Conventions for base system manuals
 .Bl -ohang
 .It Sy "Mdocdate found"
 .Pq mdoc , Nx
@@ -778,6 +816,17 @@ macro does not use CVS
 keyword substitution, but using it is conventionally expected in the
 .Ox
 base system.
+.It Sy "RCS id missing"
+.Pq Ox , Nx
+The manual page lacks the comment line with the RCS identifier
+generated by CVS
+.Ic OpenBSD
+or
+.Ic NetBSD
+keyword substitution as conventionally used in these operating systems.
+.El
+.Ss Style suggestions
+.Bl -ohang
 .It Sy "legacy man(7) date format"
 .Pq mdoc
 The
@@ -791,14 +840,6 @@ Consider using the conventional
 date format
 .Dq "Month dd, yyyy"
 instead.
-.It Sy "RCS id missing"
-.Pq Ox , Nx
-The manual page lacks the comment line with the RCS identifier
-generated by CVS
-.Ic OpenBSD
-or
-.Ic NetBSD
-keyword substitution as conventionally used in these operating systems.
 .It Sy "duplicate RCS id"
 A single manual page contains two copies of the RCS identifier for
 the same operating system.