lregex: warn if mgroup= flag is not given in --mline-regex-<LANG>=

Close #3513.
Close #2918.

Specifying mgroup is a must if --mline-regex-<LANG>= records a tag with \[0-9].

Signed-off-by: Masatake YAMATO <[email protected]>

Author: masatake

Tmain/mline-no-advance.d/stderr-expected.txt

@@ -1,3 +1,4 @@
 ctags: Notice: No options will be read from files or environment
+ctags: Warning: FOO: no {mgroup=N} flag given in --mline-regex-<LANG>=/(.)/\1/{_advanceTo=1start}... (addTagRegexOption)
 ctags: Warning: a multi line regex pattern doesn't advance the input cursor: (.)
 ctags: Warning: Language: FOO, input file: ./input.foo, pos: 0

Tmain/optlib-message-flag.d/args.ctags

@@ -12,7 +12,7 @@
 
 --mline-regex-FOO=/namespace ([a-zA-Z]+) /\1/m,mlineNamespace/{mgroup=1}{warning="got namespace"}
 --mline-regex-FOO=/var ([a-zA-Z]+) ([a-zA-Z]+);/\2/V,mlineVariable/{warning="got variable '\2' of type \1"}{mgroup=2}
---mline-regex-FOO=/bad multi-line ([a-zA-Z-]+)/\1/x,bad/{fatal="bad='\1'"}
+--mline-regex-FOO=/bad multi-line ([a-zA-Z-]+)/\1/x,bad/{fatal="bad='\1'"}{mgroup=1}
 
 
 --_tabledef-FOO=main

docs/optlib.rst

@@ -917,7 +917,7 @@ Multiline pattern flags
 
 .. TODO: Q: isn't the above restriction really a bug? I think it is. I should fix it.
    Q to @masatake-san: Do you mean that {mgroup=0} can be omitted? -> #2918 is opened
-
+   A. as proposed in #3514, I made {mgroup=N} be a must flag.
 
 ``{_advanceTo=N[start|end]}``
 

main/lregex.c

@@ -2290,8 +2290,16 @@ extern void addTagMultiLineRegex (struct lregexControlBlock *lcb, const char* co
 								  const char* const name, const char* const kinds, const char* const flags,
 								  bool *disabled)
 {
-	addTagRegexInternal (lcb, TABLE_INDEX_UNUSED,
-						 REG_PARSER_MULTI_LINE, regex, name, kinds, flags, disabled);
+	regexPattern *ptrn = addTagRegexInternal (lcb, TABLE_INDEX_UNUSED,
+											  REG_PARSER_MULTI_LINE, regex, name, kinds, flags, disabled);
+	if (ptrn->mgroup.forLineNumberDetermination == NO_MULTILINE)
+	{
+		if (hasNameSlot(ptrn))
+			error (WARNING, "%s: no {mgroup=N} flag given in --mline-regex-<LANG>=/%s/... (%s)",
+				   regex,
+				   getLanguageName (lcb->owner), ASSERT_FUNCTION);
+		ptrn->mgroup.forLineNumberDetermination = 0;
+	}
 }
 
 extern void addTagMultiTableRegex(struct lregexControlBlock *lcb,
@@ -2383,8 +2391,19 @@ static void addTagRegexOption (struct lregexControlBlock *lcb,
 		regex_pat = eStrdup (pattern);
 
 	if (parseTagRegex (regptype, regex_pat, &name, &kinds, &flags))
-		addTagRegexInternal (lcb, table_index, regptype, regex_pat, name, kinds, flags,
-							 NULL);
+	{
+		regexPattern *ptrn = addTagRegexInternal (lcb, table_index, regptype, regex_pat, name, kinds, flags,
+												  NULL);
+		if (regptype == REG_PARSER_MULTI_LINE
+			&& ptrn->mgroup.forLineNumberDetermination == NO_MULTILINE)
+		{
+			if (hasNameSlot(ptrn))
+				error (WARNING, "%s: no {mgroup=N} flag given in --mline-regex-<LANG>=%s... (%s)",
+					   getLanguageName (lcb->owner),
+					   pattern, ASSERT_FUNCTION);
+			ptrn->mgroup.forLineNumberDetermination = 0;
+		}
+	}
 
 	eFree (regex_pat);
 }