Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
Path construction &-expansions, meanings summary:
Path construction &-expansions, meanings summary:
- In build tree In source tree
- This directory just & &,
- Top level &. implies absolute &;
+ Recommended In build tree In source tree
+ when Relative Absolute Relative Absolute
+
+ This directory & &@ &, &@,
+ Top level . &@. &; &@;
+
+Adding `@' means "absolute path". (`&.' is not allowed without @
+because just `&./' is a silly way of writing `.'.) `/' terminates the
+escape (needed if the next thing is not a lowercase character, or
+space). `=' means "just the value, no /". Space starts multi-word
+processing.
-Adding `@' means "absolute path". This is not needed with &. because
-there is never any need to use &. since it would expand to nothing.
-`/' terminates the escape (needed if the next thing is not a lowercase
-character, or space). `=' means "just the value, no /". Space starts
-multi-word processing.
+In more detail, with the various options for what comes next:
Recommended In build tree In source tree
when Relative Absolute Relative Absolute
Recommended In build tree In source tree
when Relative Absolute Relative Absolute
directory any &/file &@/file &,/file &@,/file
several & f g h &@ f g h &, f g h &@, f g h
directory any &/file &@/file &,/file &@,/file
several & f g h &@ f g h &, f g h &@, f g h
- Top lc &.file &;file &@;file
- level any file &./file &;/file &@;/file
- several f g h &. f g h &; f g h &@; f g h
+ Top lc &@.file &;file &@;file
+ level any file &@./file &;/file &@;/file
+ several f g h &@. f g h &; f g h &@; f g h
.mk.in file $(abs)/file $(src)/file $(abs_src)/file
Substitution syntax
.mk.in file $(abs)/file $(src)/file $(abs_src)/file
Substitution syntax
&;lc => $(top_srcdir)/lc &;/ => $(top_srcdir)/
&@lc => $(PWD)/sub/dir/lc &@/ => $(PWD)/sub/dir/
&;lc => $(top_srcdir)/lc &;/ => $(top_srcdir)/
&@lc => $(PWD)/sub/dir/lc &@/ => $(PWD)/sub/dir/
-&.lc => $(PWD)/lc &./ => $(PWD)/
+&@.lc => $(PWD)/lc &@./ => $(PWD)/
&@,lc => $(abs_top_srcdir)/sub/dir/lc &@,/ => $(abs_top_srcdir)/sub/dir/
&@;lc => $(abs_top_srcdir)/lc &@;/ => $(abs_top_srcdir)/
&@,lc => $(abs_top_srcdir)/sub/dir/lc &@,/ => $(abs_top_srcdir)/sub/dir/
&@;lc => $(abs_top_srcdir)/lc &@;/ => $(abs_top_srcdir)/
= return subdir without delimiter (not allowed with `,' `;' `@')
, pathname of this subdirectory in source tree
; pathname of top level of source tree
= return subdir without delimiter (not allowed with `,' `;' `@')
, pathname of this subdirectory in source tree
; pathname of top level of source tree
- . pathname of this directory in build tree, implies absolute pathnames
- @ absolute pathnames (forbidden with `.', must come first)
+ . pathname of this directory in build tree, `@' must be specified
+ @ absolute pathnames
So pathname syntax is a subset of:
'&' [ '@' ] [ ',' | ';' | '.' ] [ lc | '/' ]
To avoid incomprehensible .sd.mk files, some combinations are not
So pathname syntax is a subset of:
'&' [ '@' ] [ ',' | ';' | '.' ] [ lc | '/' ]
To avoid incomprehensible .sd.mk files, some combinations are not
- allowed. For example `&@=./' would mean `$(PWD)/sub/dir' but can
- be spelled `$(PWD)/&=/', but more normally the trailing / can be
- tolerated, so use `&@/'.
+ allowed. For example `&=./' would mean `.' and `&./' would be the
+ empty string. Variations with `=' and one of `@' `,' `;' are
+ uncommon and must be written using make variables instead.
&& => && for convenience in shell runes
\& => & general escaping mechanism
&& => && for convenience in shell runes
\& => & general escaping mechanism