xgettext: Support message syntax checks

With this change, xgettext could report common syntactic problems
in extracted strings.  The current built-in checks are
ellipsis-unicode, space-ellipsis, and quote-unicode.  Those checks
can be enabled with --check option of xgettext and disabled with
special "xgettext:" comment in source files.
Feature suggested by Philip Withnall in:
https://savannah.gnu.org/bugs/?44098
* gettext-tools/src/message.h (enum syntax_check_type): New enum.
(NSYNTAXCHECKS): New constant.
(enum is_syntax_check): New enum.
(struct message_ty): New field 'do_syntax_check'.
(syntax_check_name): New variable declaration.
* gettext-tools/src/message.c (syntax_check_name): New variable.
* gettext-tools/src/msgl-cat.c (catenate_msgdomain_list): Propagate
mp->do_syntax_check.
* gettext-tools/src/msgmerge.c (message_merge): Propagate
ref->do_syntax_check.
* gettext-tools/src/msgl-check.h (syntax_check_message_list): New
declaration.
* gettext-tools/src/msgl-check.c (sentence_end): New function.
(syntax_check_ellipsis_unicode): New function.
(syntax_check_space_ellipsis): New function.
(syntax_check_quote_unicode): New function.
(syntax_check_message): New function.
(syntax_check_message_list): New function.
* gettext-tools/src/read-catalog-abstract.h (po_parse_comment_special):
Adjust function declaration.
* gettext-tools/src/read-catalog-abstract.c (po_parse_comment_special):
Add new argument SCP for syntax checking; all callers changed.
* gettext-tools/src/read-catalog.h (DEFAULT_CATALOG_READER_TY): New
field 'do_syntax_check'.
* gettext-tools/src/read-catalog.c (default_constructor): Initialize
this->do_syntax_check.
(default_copy_comment_state): Propagate this->do_syntax_check.
* gettext-tools/src/xgettext.c (long_options): Add --check option.
(main): Handle --check option.
(usage): Document --check option.
(remember_a_message): Propagate do_syntax_check value.

* gettext-tools/tests/xgettext-14: New file.
* gettext-tools/tests/sentence.c: New file.
* gettext-tools/tests/Makefile.am (TESTS): Add new test.
(noinst_PROGRAMS): Add 'sentence'.
(sentence_SOURCES): New variable.
(sentence_CPPFLAGS): New variable.
(sentence_LDADD): New variable.

* gettext-tools/doc/xgettext.texi: Document --check option.

1 files changed, 6 insertions, 3 deletions

diff --git a/gettext-tools/tests/Makefile.am b/gettext-tools/tests/Makefile.am
index 32bc192..ea8bfa9 100644
--- a/gettext-tools/tests/Makefile.am
+++ b/gettext-tools/tests/Makefile.am
@@ -72,7 +72,7 @@ TESTS = gettext-1 gettext-2 gettext-3 gettext-4 gettext-5 gettext-6 gettext-7 \
 	recode-sr-latin-1 recode-sr-latin-2 \
 	xgettext-2 xgettext-3 xgettext-4 xgettext-5 xgettext-6 \
 	xgettext-7 xgettext-8 xgettext-9 xgettext-10 xgettext-11 xgettext-12 \
-	xgettext-13 \
+	xgettext-13 xgettext-14 \
 	xgettext-awk-1 xgettext-awk-2 \
 	xgettext-c-2 xgettext-c-3 xgettext-c-4 xgettext-c-5 \
 	xgettext-c-6 xgettext-c-7 xgettext-c-8 xgettext-c-9 xgettext-c-10 \
@@ -137,7 +137,7 @@ TESTS = gettext-1 gettext-2 gettext-3 gettext-4 gettext-5 gettext-6 gettext-7 \
 	format-lua-1 format-lua-2 \
 	format-javascript-1 format-javascript-2 \
 	plural-1 plural-2 \
-	gettextpo-1 \
+	gettextpo-1 sentence \
 	lang-c lang-c++ lang-objc lang-sh lang-bash lang-python-1 \
 	lang-python-2 lang-clisp lang-elisp lang-librep lang-guile \
 	lang-smalltalk lang-java lang-csharp lang-gawk lang-pascal \
@@ -211,7 +211,7 @@ DEFS = -DLOCALEDIR=\"$(localedir)\" @DEFS@
 LDADD = $(LDADD_@USE_INCLUDED_LIBINTL@) @INTL_MACOSX_LIBS@
 LDADD_yes = ../intl/libintl.la @LTLIBTHREAD@
 LDADD_no = ../intl/libgnuintl.la @LTLIBTHREAD@ @LTLIBINTL@
-noinst_PROGRAMS = tstgettext tstngettext testlocale gettext-3-prg gettext-4-prg gettext-5-prg gettext-6-prg gettext-7-prg gettext-8-prg cake fc3 fc4 fc5 gettextpo-1-prg
+noinst_PROGRAMS = tstgettext tstngettext testlocale gettext-3-prg gettext-4-prg gettext-5-prg gettext-6-prg gettext-7-prg gettext-8-prg cake fc3 fc4 fc5 gettextpo-1-prg sentence
 tstgettext_SOURCES = tstgettext.c setlocale.c
 tstgettext_CFLAGS = -DINSTALLDIR=\".\"
 tstgettext_LDADD = ../gnulib-lib/libgettextlib.la $(LDADD)
@@ -255,6 +255,9 @@ gettextpo_1_prg_CPPFLAGS = \
 # Don't add more libraries here. This test must check whether libgettextpo is
 # self contained.
 gettextpo_1_prg_LDADD = ../libgettextpo/libgettextpo.la $(LDADD)
+sentence_SOURCES = sentence.c
+sentence_CPPFLAGS = -I../src -I../gnulib-lib
+sentence_LDADD = ../src/libgettextsrc.la $(LDADD)
 
 # Clean up after Solaris cc.
 clean-local: