cfg.mk: remove comments with sed rather than cpp -fpreprocessed

* cfg.mk (_sed_remove_comments): Define, starting with gettext's
moopp sed code, but factoring it to be more understandable.
(sc_space_before_open_paren): Adapt.
Prompted by Bruno Haible's suggestion to use gettext's moopp code.

diff --git a/cfg.mk b/cfg.mk
index 0ce1c619c7622534785aeb9747ae2ccf8ffd168b..11403ac368a2fa21ea408a7802dc4151e0a35bc2 100644 (file)
--- a/cfg.mk
+++ b/cfg.mk
@@ -261,27 +261,56 @@ sc_prohibit_sleep:
        msg='prefer xnanosleep over other sleep interfaces'             \
          $(_prohibit_regexp)
 
+###########################################################
+_p0 = \([^"'/]\|"\([^\"]\|[\].\)*"\|'\([^\']\|[\].\)*'
+_pre = $(_p0)\|[/][^"'/*]\|[/]"\([^\"]\|[\].\)*"\|[/]'\([^\']\|[\].\)*'\)*
+_pre_anchored = ^\($(_pre)\)
+_comment_and_close = [^*]\|[*][^/*]\)*[*][*]*/
+# help font-lock mode: '
+
+# A sed expression that removes ANSI C and ISO C99 comments.
+# Derived from the one in GNU gettext's 'moopp' preprocessor.
+_sed_remove_comments =                                 \
+/[/][/*]/{                                             \
+  ta;                                                  \
+  :a;                                                  \
+  s,$(_pre_anchored)//.*,\1,;                          \
+  te;                                                  \
+  s,$(_pre_anchored)/[*]\($(_comment_and_close),\1 ,;  \
+  ta;                                                  \
+  /^$(_pre)[/][*]/{                                    \
+    s,$(_pre_anchored)/[*].*,\1 ,;                     \
+    tu;                                                        \
+    :u;                                                        \
+    n;                                                 \
+    s,^\($(_comment_and_close),,;                      \
+    tv;                                                        \
+    s,^.*$$,,;                                         \
+    bu;                                                        \
+    :v;                                                        \
+  };                                                   \
+  :e;                                                  \
+}
+# Quote all single quotes.
+_sed_rm_comments_q = $(subst ','\'',$(_sed_remove_comments))
+# help font-lock mode: '
+
 _space_before_paren_exempt =? \\n\\$$
 _space_before_paren_exempt = \
-  (\\n\\$$|%s\(to %s|delimit-method|(date|group|character)\(s\))
+  (^ *\#|\\n\\$$|%s\(to %s|(date|group|character)\(s\))
 # Ensure that there is a space before each open parenthesis in C code.
 sc_space_before_open_paren:
        @if $(VC_LIST_EXCEPT) | grep -l '\.[ch]$$' > /dev/null; then    \
-         if (cpp -fpreprocessed < /dev/null > /dev/null 2>&1); then    \
-           fail=0;                                                     \
-           for c in $$($(VC_LIST_EXCEPT) | grep '\.[ch]$$'); do        \
-             cpp -fpreprocessed $$c 2>/dev/null                        \
-               | grep -ni '[[:alnum:]]('                               \
-               | grep -vE '$(_space_before_paren_exempt)'              \
-               | grep . && { fail=1; echo "*** $$c"; };                \
-           done;                                                       \
-           test $$fail = 1 &&                                          \
-             { echo '$(ME): the above files lack a space-before-open-paren' \
-                 1>&2; exit 1; } || :;                                 \
-         else                                                          \
-           echo '$(ME): skipping test $@: cpp -fpreprocessed does not work' \
-             1>&2;                                                     \
-         fi;                                                           \
+         fail=0;                                                       \
+         for c in $$($(VC_LIST_EXCEPT) | grep '\.[ch]$$'); do          \
+           sed '$(_sed_rm_comments_q)' $$c 2>/dev/null                 \
+             | grep -i '[[:alnum:]]('                                  \
+             | grep -vE '$(_space_before_paren_exempt)'                \
+             | grep . && { fail=1; echo "*** $$c"; };                  \
+         done;                                                         \
+         test $$fail = 1 &&                                            \
+           { echo '$(ME): the above files lack a space-before-open-paren' \
+               1>&2; exit 1; } || :;                                   \
        else :;                                                         \
        fi