patch 8.2.2295: incsearch does not detect empty pattern properly

Problem:    Incsearch does not detect empty pattern properly.
Solution:   Return magic state when skipping over a pattern. (Christian
            Brabandt, closes #7612, closes #6420)

Author: brammool

src/ex_cmds.c

@@ -3672,7 +3672,7 @@ ex_substitute(exarg_T *eap)
 	    delimiter = *cmd++;		    // remember delimiter character
 	    pat = cmd;			    // remember start of search pat
 	    cmd = skip_regexp_ex(cmd, delimiter, magic_isset(),
-							      &eap->arg, NULL);
+							&eap->arg, NULL, NULL);
 	    if (cmd[0] == delimiter)	    // end delimiter found
 		*cmd++ = NUL;		    // replace it with a NUL
 	}
@@ -4856,7 +4856,7 @@ ex_global(exarg_T *eap)
 	if (delim)
 	    ++cmd;		// skip delimiter if there is one
 	pat = cmd;		// remember start of pattern
-	cmd = skip_regexp_ex(cmd, delim, magic_isset(), &eap->arg, NULL);
+	cmd = skip_regexp_ex(cmd, delim, magic_isset(), &eap->arg, NULL, NULL);
 	if (cmd[0] == delim)		    // end delimiter found
 	    *cmd++ = NUL;		    // replace it with a NUL
     }

src/ex_docmd.c

@@ -7529,9 +7529,10 @@ ex_may_print(exarg_T *eap)
     static void
 ex_submagic(exarg_T *eap)
 {
-    magic_T saved = magic_overruled;
+    optmagic_T saved = magic_overruled;
 
-    magic_overruled = eap->cmdidx == CMD_smagic ? MAGIC_ON : MAGIC_OFF;
+    magic_overruled = eap->cmdidx == CMD_smagic
+					  ? OPTION_MAGIC_ON : OPTION_MAGIC_OFF;
     ex_substitute(eap);
     magic_overruled = saved;
 }

src/ex_getln.c

@@ -52,6 +52,9 @@ static void	restore_cmdline(cmdline_info_T *ccp);
 static int	cmdline_paste(int regname, int literally, int remcr);
 static void	redrawcmdprompt(void);
 static int	ccheck_abbr(int);
+#ifdef FEAT_SEARCH_EXTRA
+static int	empty_pattern_magic(char_u *pat, size_t len, magic_T magic_val);
+#endif
 
 #ifdef FEAT_CMDWIN
 static int	open_cmdwin(void);
@@ -89,15 +92,34 @@ abandon_cmdline(void)
  * as a trailing \|, which can happen while typing a pattern.
  */
     static int
-empty_pattern(char_u *p)
+empty_pattern(char_u *p, int delim)
 {
-    size_t n = STRLEN(p);
+    size_t	n = STRLEN(p);
+    magic_T	magic_val = MAGIC_ON;
+
+    if (n > 0)
+	(void) skip_regexp_ex(p, delim, magic_isset(), NULL, NULL, &magic_val);
+    else
+	return TRUE;
 
+    return empty_pattern_magic(p, n, magic_val);
+}
+
+    static int
+empty_pattern_magic(char_u *p, size_t len, magic_T magic_val)
+{
     // remove trailing \v and the like
-    while (n >= 2 && p[n - 2] == '\\'
-			  && vim_strchr((char_u *)"mMvVcCZ", p[n - 1]) != NULL)
-	n -= 2;
-    return n == 0 || (n >= 2 && p[n - 2] == '\\' && p[n - 1] == '|');
+    while (len >= 2 && p[len - 2] == '\\'
+                        && vim_strchr((char_u *)"mMvVcCZ", p[len - 1]) != NULL)
+       len -= 2;
+
+    // true, if the pattern is empty, or the pattern ends with \| and magic is
+    // set (or it ends with '|' and very magic is set)
+    return len == 0 || (len > 1
+	    && ((p[len - 2] == '\\'
+				 && p[len - 1] == '|' && magic_val == MAGIC_ON)
+		|| (p[len - 2] != '\\'
+			     && p[len - 1] == '|' && magic_val == MAGIC_ALL)));
 }
 
 // Struct to store the viewstate during 'incsearch' highlighting.
@@ -149,7 +171,7 @@ typedef struct {
     pos_T	match_end;
     int		did_incsearch;
     int		incsearch_postponed;
-    magic_T	magic_overruled_save;
+    optmagic_T	magic_overruled_save;
 } incsearch_state_T;
 
     static void
@@ -207,6 +229,7 @@ do_incsearch_highlighting(
     pos_T	save_cursor;
     int		use_last_pat;
     int		retval = FALSE;
+    magic_T     magic = 0;
 
     *skiplen = 0;
     *patlen = ccline.cmdlen;
@@ -252,9 +275,9 @@ do_incsearch_highlighting(
 	    || STRNCMP(cmd, "vglobal", p - cmd) == 0)
     {
 	if (*cmd == 's' && cmd[1] == 'm')
-	    magic_overruled = MAGIC_ON;
+	    magic_overruled = OPTION_MAGIC_ON;
 	else if (*cmd == 's' && cmd[1] == 'n')
-	    magic_overruled = MAGIC_OFF;
+	    magic_overruled = OPTION_MAGIC_OFF;
     }
     else if (STRNCMP(cmd, "sort", MAX(p - cmd, 3)) == 0)
     {
@@ -288,7 +311,7 @@ do_incsearch_highlighting(
     p = skipwhite(p);
     delim = (delim_optional && vim_isIDc(*p)) ? ' ' : *p++;
     *search_delim = delim;
-    end = skip_regexp(p, delim, magic_isset());
+    end = skip_regexp_ex(p, delim, magic_isset(), NULL, NULL, &magic);
 
     use_last_pat = end == p && *end == delim;
 
@@ -302,7 +325,7 @@ do_incsearch_highlighting(
 	int  empty;
 
 	*end = NUL;
-	empty = empty_pattern(p);
+	empty = empty_pattern_magic(p, STRLEN(p), magic);
 	*end = c;
 	if (empty)
 	    goto theend;
@@ -535,7 +558,8 @@ may_do_incsearch_highlighting(
     {
 	next_char = ccline.cmdbuff[skiplen + patlen];
 	ccline.cmdbuff[skiplen + patlen] = NUL;
-	if (empty_pattern(ccline.cmdbuff) && !no_hlsearch)
+	if (empty_pattern(ccline.cmdbuff + skiplen, search_delim)
+							       && !no_hlsearch)
 	{
 	    redraw_all_later(SOME_VALID);
 	    set_no_hlsearch(TRUE);

src/globals.h

@@ -1945,7 +1945,6 @@ EXTERN int channel_need_redraw INIT(= FALSE);
 #define FOR_ALL_LIST_ITEMS(l, li) \
     for ((li) = (l)->lv_first; (li) != NULL; (li) = (li)->li_next)
 
-// While executing a regexp and set to MAGIC_ON or MAGIC_OFF this overrules
-// p_magic.  Otherwise set to MAGIC_NOT_SET.
-
-EXTERN magic_T magic_overruled INIT(= MAGIC_NOT_SET);
+// While executing a regexp and set to OPTION_MAGIC_ON or OPTION_MAGIC_OFF this
+// overrules p_magic.  Otherwise set to OPTION_MAGIC_NOT_SET.
+EXTERN optmagic_T magic_overruled INIT(= OPTION_MAGIC_NOT_SET);

src/option.c

@@ -7009,9 +7009,9 @@ magic_isset(void)
 {
     switch (magic_overruled)
     {
-	case MAGIC_ON:      return TRUE;
-	case MAGIC_OFF:     return FALSE;
-	case MAGIC_NOT_SET: break;
+	case OPTION_MAGIC_ON:      return TRUE;
+	case OPTION_MAGIC_OFF:     return FALSE;
+	case OPTION_MAGIC_NOT_SET: break;
     }
 #ifdef FEAT_EVAL
     if (in_vim9script())

src/proto/regexp.pro

@@ -2,7 +2,7 @@
 int re_multiline(regprog_T *prog);
 char_u *skip_regexp(char_u *startp, int delim, int magic);
 char_u *skip_regexp_err(char_u *startp, int delim, int magic);
-char_u *skip_regexp_ex(char_u *startp, int dirc, int magic, char_u **newp, int *dropped);
+char_u *skip_regexp_ex(char_u *startp, int dirc, int magic, char_u **newp, int *dropped, magic_T *magic_val);
 reg_extmatch_T *ref_extmatch(reg_extmatch_T *em);
 void unref_extmatch(reg_extmatch_T *em);
 char_u *regtilde(char_u *source, int magic);

src/regexp.c

@@ -304,11 +304,7 @@ static unsigned	regflags;	// RF_ flags for prog
 static int	had_eol;	// TRUE when EOL found by vim_regcomp()
 #endif
 
-static int	reg_magic;	// magicness of the pattern:
-#define MAGIC_NONE	1	// "\V" very unmagic
-#define MAGIC_OFF	2	// "\M" or 'magic' off
-#define MAGIC_ON	3	// "\m" or 'magic'
-#define MAGIC_ALL	4	// "\v" very magic
+static magic_T	reg_magic;	// magicness of the pattern
 
 static int	reg_string;	// matching with a string instead of a buffer
 				// line
@@ -548,7 +544,7 @@ skip_regexp(
     int		delim,
     int		magic)
 {
-    return skip_regexp_ex(startp, delim, magic, NULL, NULL);
+    return skip_regexp_ex(startp, delim, magic, NULL, NULL, NULL);
 }
 
 /*
@@ -577,16 +573,18 @@ skip_regexp_err(
  * expression and change "\?" to "?".  If "*newp" is not NULL the expression
  * is changed in-place.
  * If a "\?" is changed to "?" then "dropped" is incremented, unless NULL.
+ * If "magic_val" is not NULL, returns the effective magicness of the pattern
  */
     char_u *
 skip_regexp_ex(
     char_u	*startp,
     int		dirc,
     int		magic,
     char_u	**newp,
-    int		*dropped)
+    int		*dropped,
+    magic_T	*magic_val)
 {
-    int		mymagic;
+    magic_T	mymagic;
     char_u	*p = startp;
 
     if (magic)
@@ -632,6 +630,8 @@ skip_regexp_ex(
 		mymagic = MAGIC_NONE;
 	}
     }
+    if (magic_val != NULL)
+	*magic_val = mymagic;
     return p;
 }
 

src/search.c

@@ -1342,7 +1342,7 @@ do_search(
 	     */
 	    ps = strcopy;
 	    p = skip_regexp_ex(pat, search_delim, magic_isset(),
-							       &strcopy, NULL);
+							&strcopy, NULL, NULL);
 	    if (strcopy != ps)
 	    {
 		// made a copy of "pat" to change "\?" to "?"

src/structs.h

@@ -4321,8 +4321,20 @@ typedef struct
 // with iconv() to be able to allocate a buffer.
 #define ICONV_MULT 8
 
+// Used for "magic_overruled".
 typedef enum {
-    MAGIC_NOT_SET,	// p_magic not overruled
-    MAGIC_ON,		// magic on inside regexp
-    MAGIC_OFF		// magic off inside regexp
+    OPTION_MAGIC_NOT_SET,	// p_magic not overruled
+    OPTION_MAGIC_ON,		// magic on inside regexp
+    OPTION_MAGIC_OFF		// magic off inside regexp
+} optmagic_T;
+
+// Magicness of a pattern, used by regexp code.
+// The order and values matter:
+//  magic <= MAGIC_OFF includes MAGIC_NONE
+//  magic >= MAGIC_ON  includes MAGIC_ALL
+typedef enum {
+    MAGIC_NONE = 1,		// "\V" very unmagic
+    MAGIC_OFF = 2,		// "\M" or 'magic' off
+    MAGIC_ON = 3,		// "\m" or 'magic'
+    MAGIC_ALL = 4		// "\v" very magic
 } magic_T;

src/tag.c

@@ -3312,7 +3312,7 @@ jumpto_tag(
     int		keep_help)	// keep help flag (FALSE for cscope)
 {
     int		save_secure;
-    int		save_magic_overruled;
+    optmagic_T	save_magic_overruled;
     int		save_p_ws, save_p_scs, save_p_ic;
     linenr_T	save_lnum;
     char_u	*str;
@@ -3505,7 +3505,7 @@ jumpto_tag(
 	++sandbox;
 #endif
 	save_magic_overruled = magic_overruled;
-	magic_overruled = MAGIC_OFF;	// always execute with 'nomagic'
+	magic_overruled = OPTION_MAGIC_OFF;	// always execute with 'nomagic'
 #ifdef FEAT_SEARCH_EXTRA
 	// Save value of no_hlsearch, jumping to a tag is not a real search
 	save_no_hlsearch = no_hlsearch;