doc: %reldir% and %canon_reldir% do not expand to the empty string.

This change fixes https://bugs.gnu.org/52500.

* doc/automake.texi (Include): correct wrong text.
(Along the way, correct plain-text "Makefile" to "@file{Makefile}".)

diff --git a/doc/automake.texi b/doc/automake.texi
index 47f49a49b63ea0c2114a7478e5b6751fd26dff3f..55fc3f72e8b590ffd647db9de6763efc8651bfb9 100644 (file)
--- a/doc/automake.texi
+++ b/doc/automake.texi
@@ -1840,7 +1840,7 @@ variable definitions.
 @cindex Automake parser, limitations of
 @cindex indentation in Makefile.am
 Generally, Automake is not particularly smart in the parsing of unusual
-Makefile constructs, so you're advised to avoid fancy constructs or
+@file{Makefile} constructs, so you're advised to avoid fancy constructs or
 ``creative'' use of whitespace.
 @c Keep this in sync with doc-parsing-buglets-tabs.sh
 For example, @key{TAB} characters cannot be used between a target name
@@ -1971,7 +1971,7 @@ of the GNU standards.
 
 Future versions of Automake may, at this level of strictness, require
 certain non-standard GNU tools to be available to maintainer-only
-Makefile rules.  For instance, in the future @command{pathchk}
+@file{Makefile} rules.  For instance, in the future @command{pathchk}
 (@pxref{pathchk invocation,,, coreutils, GNU Coreutils})
 may be required to run @samp{make dist}.
 
@@ -5459,7 +5459,7 @@ Convenience libraries listed in @code{noinst_LTLIBRARIES} are always
 built.  Those listed in @code{check_LTLIBRARIES} are built only upon
 @samp{make check}.  Finally, libraries listed in
 @code{EXTRA_LTLIBRARIES} are never built explicitly: Automake outputs
-rules to build them, but if the library does not appear as a Makefile
+rules to build them, but if the library does not appear as a @file{Makefile}
 dependency anywhere it won't be built (this is why
 @code{EXTRA_LTLIBRARIES} is used for conditional compilation).
 
@@ -10900,7 +10900,7 @@ Include a fragment that is found relative to the top source directory.
 Note that if a fragment is included inside a conditional, then the
 condition applies to the entire contents of that fragment.
 
-Makefile fragments included this way are always distributed because
+@file{Makefile} fragments included this way are always distributed because
 they are needed to rebuild @file{Makefile.in}.
 
 Inside a fragment, the construct @code{%reldir%} is replaced with the
@@ -10911,12 +10911,20 @@ Similarly, @code{%canon_reldir%} is replaced with the canonicalized
 is a synonym for @code{%canon_reldir%}.
 
 A special feature is that if the fragment is in the same directory as
-the base @file{Makefile.am} (i.e., @code{%reldir%} is @code{.}), then
-@code{%reldir%} and @code{%canon_reldir%} will expand to the empty
-string as well as eat, if present, a following slash or underscore
-respectively.
+the base @file{Makefile.am} (i.e., @code{%reldir%} is @code{.}), then:
+
+@table @code
+@item %reldir%
+together with a following slash expands to the empty string, otherwise
+it expands to a dot;
+
+@item %canon_reldir%
+together with a following underscore expands to the empty string, otherwise
+it expands to an underscore.
+
+@end table
 
-Thus, a makefile fragment might look like this:
+Thus, a @file{Makefile} fragment might look like this:
 
 @example
 bin_PROGRAMS += %reldir%/mumble
@@ -11711,7 +11719,7 @@ The necessary substitutions: @samp{@@srcdir@@}, @samp{@@top_srcdir@@},
 and @samp{@@top_builddir@@} are defined by @file{configure} when it
 processes a @file{Makefile} (@pxref{Preset Output Variables, , Preset
 Output Variables, autoconf, The Autoconf Manual}); they are not
-computed by the Makefile like the aforementioned @samp{$(distdir)} and
+computed by the @file{Makefile} like the aforementioned @samp{$(distdir)} and
 @samp{$(top_distdir)} variables.
 
 It is sometimes inconvenient to modify a third-party @file{Makefile}