master b0d799c0161 2/2: Don't build untranslated doc directories per language (bug#81332)

branch: master
commit b0d799c0161c64744c29853097aeb2578dfd6a08
Author: Boris Buliga <[email protected]>
Commit: Eli Zaretskii <[email protected]>

    Don't build untranslated doc directories per language (bug#81332)
    
    With DOCLANGS='default fr', the top-level doc targets ran a sub-make
    in every doc directory once per language.  The Makefiles of the
    directories without translations (emacs, lispintro, lispref) ignore
    DOCLANG, so the non-default sub-make repeated the default-language
    build, and under "make -j" two sub-makes produced the same outputs
    concurrently, failing intermittently with:
    
      cp: cannot create regular file '../../info/cons-2a.txt': File exists
    
    * Makefile.in (FILTER_DOCLANGS): New function: languages from
    DOCLANGS to build for a doc directory, the default language when
    present in DOCLANGS plus every language that has translations for
    this directory (doc/translations/<lang>/<dir>).  Do not force the
    default language when DOCLANGS omits it.  Suggested by Vincent
    Belaiche <[email protected]>.
    (MAKE_DOC): Take the list of languages as a second argument and use
    it instead of DOCLANGS.
---
 Makefile.in | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/Makefile.in b/Makefile.in
index 4933c077788..534d8dca38f 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -1151,15 +1151,26 @@ $(1)-DOCLANG-$(2): $(1)-common
 	$$(MAKE) -C doc/$$(subst -, DOCLANG=$(2) ,$(1))
 
 endef
+## Languages from DOCLANGS to build the manuals in doc/$(1) for: the
+## default language (when in DOCLANGS), plus every other language in
+## DOCLANGS that has translations for this directory
+## (doc/translations/<lang>/$(1)).  Directories without translations
+## for a language must not run a sub-make for it: the doc Makefiles of
+## untranslated directories ignore DOCLANG, so such a sub-make would
+## just repeat the default-language build, and two sub-makes producing
+## the same outputs race under "make -j" (e.g. "cp: cannot create
+## regular file ...: File exists").
+FILTER_DOCLANGS = $(filter $(DOCLANGS),default) $(foreach lang,$(filter-out default,$(DOCLANGS)),$(if $(wildcard ${srcdir}/doc/translations/$(lang)/$(1)),$(lang)))
+# $(1) = doc target (e.g. lispintro-info), $(2) = languages to build
 define MAKE_DOC
 # Define a target to which dependencies common to all of the doc files
 # in this directory may be assigned.
 $(1)-common:
-$(1): $$(addprefix $(1)-DOCLANG-,$(DOCLANGS))
+$(1): $$(addprefix $(1)-DOCLANG-,$(2))
 
-$$(foreach lang,$(DOCLANGS),$$(eval $$(call MAKE_DOC_FOR_DOCLANG,$(1),$$(lang))))
+$$(foreach lang,$(2),$$(eval $$(call MAKE_DOC_FOR_DOCLANG,$(1),$$(lang))))
 endef
-$(foreach doc,$(DOCS),$(eval $(call MAKE_DOC,$(doc))))
+$(foreach doc,$(DOCS),$(eval $(call MAKE_DOC,$(doc),$(call FILTER_DOCLANGS,$(word 1,$(subst -, ,$(doc)))))))
 
 .PHONY: $(DOCS) docs pdf ps
 .PHONY: info dvi dist html info-dir check-info