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| author | Dmitry Goncharov <dgoncharov@users.sf.net> | 2022-07-24 18:16:50 -0400 |
|---|---|---|
| committer | Paul Smith <psmith@gnu.org> | 2022-07-30 18:40:28 -0400 |
| commit | 07eea3aa496184bb763b7306e9de6a40a94605c9 (patch) | |
| tree | f0b5e2b330b6ef40627b7050738c603aec4cd79b /doc | |
| parent | 16e14b4114c0c9cc14d15e818bf22588a79e39da (diff) | |
| download | make-git-07eea3aa496184bb763b7306e9de6a40a94605c9.tar.gz | |
[SV 62706] Only second-expand targets that might be built
Second-expand only the prerequisites of the targets being built.
Defer second-expanding the prerequisites of targets until we need
to decide if they should be built.
* NEWS: Mention the change in behavior.
* doc/make.texi (Secondary Expansion): Document the new behavior.
* src/filedef.h (struct file): Add flag snapped.
(expand_deps): Declare a function to second expand the
prerequisites of a target.
* src/file.c (rehash_file): Merge flag snapped.
(expand_deps): Remove qualifier static. Check flag snapped.
(snap_deps): Remove the loop which performed second expansion for all
targets.
* src/remake.c (update_file_1): Second expand the prerequisites of
the considered target.
* tests/scripts/features/se_explicit: Add tests.
* tests/scripts/features/se_implicit: Ditto.
* tests/scripts/features/se_statpat: Ditto.
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/make.texi | 22 |
1 files changed, 10 insertions, 12 deletions
diff --git a/doc/make.texi b/doc/make.texi index 085e9c24..49cdb0b2 100644 --- a/doc/make.texi +++ b/doc/make.texi @@ -1703,18 +1703,16 @@ this second expansion to occur, the special target @code{.SECONDEXPANSION} must be defined before the first prerequisite list that makes use of this feature. -If that special target is defined then in between the two phases -mentioned above, right at the end of the read-in phase, all the -prerequisites of the targets defined after the special target are -expanded a @emph{second time}. In most circumstances this secondary -expansion will have no effect, since all variable and function -references will have been expanded during the initial parsing of the -makefiles. In order to take advantage of the secondary expansion -phase of the parser, then, it's necessary to @emph{escape} the -variable or function reference in the makefile. In this case the -first expansion merely un-escapes the reference but doesn't expand it, -and expansion is left to the secondary expansion phase. For example, -consider this makefile: +If @code{.SECONDEXPANSION} is defined then when GNU @code{make} needs to check +the prerequisites of a target, the prerequisites are expanded a @emph{second +time}. In most circumstances this secondary expansion will have no effect, +since all variable and function references will have been expanded during the +initial parsing of the makefiles. In order to take advantage of the secondary +expansion phase of the parser, then, it's necessary to @emph{escape} the +variable or function reference in the makefile. In this case the first +expansion merely un-escapes the reference but doesn't expand it, and expansion +is left to the secondary expansion phase. For example, consider this +makefile: @example .SECONDEXPANSION: |