src/regex-emacs.c (POS_AS_IN_BUFFER): Delete macro

That macro added 1 to buffer positions because:

    Strings are 0-indexed, buffers are 1-indexed

but the reality is that this 1 was added to the regexp engine's "byte
offsets" which are not 1-based byte positions as used throughout
the rest of Emacs, but they are BEGV_BYTE-relative offsets, so the two
did not cancel out.

* src/regex-emacs.c (PTR_TO_OFFSET, POS_AS_IN_BUFFER): Delete macros;
use `POINTER_TO_OFFSET` instead.
(re_search_2, re_match_2, re_match_2_internal): Adjust accordingly.
* src/syntax.h (SYNTAX_TABLE_BYTE_TO_CHAR): Don't remove 1 from buffer
byteoffsets now that `POS_AS_IN_BUFFER` doesn't add it any more.

2 files changed, 14 insertions, 21 deletions

diff --git a/src/regex-emacs.c b/src/regex-emacs.c
index 2571812cb39..969f2ff9464 100644
--- a/src/regex-emacs.c
+++ b/src/regex-emacs.c
@@ -47,13 +47,6 @@
 /* Make syntax table lookup grant data in gl_state.  */
 #define SYNTAX(c) syntax_property (c, 1)
 
-/* Convert the pointer to the char to BEG-based offset from the start.  */
-#define PTR_TO_OFFSET(d) POS_AS_IN_BUFFER (POINTER_TO_OFFSET (d))
-/* Strings are 0-indexed, buffers are 1-indexed; pun on the boolean
-   result to get the right base index.  */
-#define POS_AS_IN_BUFFER(p)                                    \
-  ((p) + (NILP (gl_state.object) || BUFFERP (gl_state.object)))
-
 #define RE_MULTIBYTE_P(bufp) ((bufp)->multibyte)
 #define RE_TARGET_MULTIBYTE_P(bufp) ((bufp)->target_multibyte)
 #define RE_STRING_CHAR(p, multibyte) \
@@ -3260,7 +3253,7 @@ re_search_2 (struct re_pattern_buffer *bufp, const char *str1, ptrdiff_t size1,
 
   gl_state.object = re_match_object; /* Used by SYNTAX_TABLE_BYTE_TO_CHAR. */
   {
-    ptrdiff_t charpos = SYNTAX_TABLE_BYTE_TO_CHAR (POS_AS_IN_BUFFER (startpos));
+    ptrdiff_t charpos = SYNTAX_TABLE_BYTE_TO_CHAR (startpos);
 
     SETUP_SYNTAX_TABLE_FOR_OBJECT (re_match_object, charpos, 1);
   }
@@ -3873,7 +3866,7 @@ re_match_2 (struct re_pattern_buffer *bufp,
 
   ptrdiff_t charpos;
   gl_state.object = re_match_object; /* Used by SYNTAX_TABLE_BYTE_TO_CHAR. */
-  charpos = SYNTAX_TABLE_BYTE_TO_CHAR (POS_AS_IN_BUFFER (pos));
+  charpos = SYNTAX_TABLE_BYTE_TO_CHAR (pos);
   SETUP_SYNTAX_TABLE_FOR_OBJECT (re_match_object, charpos, 1);
 
   result = re_match_2_internal (bufp, (re_char *) string1, size1,
@@ -4806,7 +4799,7 @@ re_match_2_internal (struct re_pattern_buffer *bufp,
 		int c1, c2;
 		int s1, s2;
 		int dummy;
-                ptrdiff_t offset = PTR_TO_OFFSET (d);
+                ptrdiff_t offset = POINTER_TO_OFFSET (d);
                 ptrdiff_t charpos = SYNTAX_TABLE_BYTE_TO_CHAR (offset) - 1;
 		UPDATE_SYNTAX_TABLE (charpos);
 		GET_CHAR_BEFORE_2 (c1, d, string1, end1, string2, end2);
@@ -4846,7 +4839,7 @@ re_match_2_internal (struct re_pattern_buffer *bufp,
 	      int c1, c2;
 	      int s1, s2;
 	      int dummy;
-	      ptrdiff_t offset = PTR_TO_OFFSET (d);
+	      ptrdiff_t offset = POINTER_TO_OFFSET (d);
 	      ptrdiff_t charpos = SYNTAX_TABLE_BYTE_TO_CHAR (offset);
 	      UPDATE_SYNTAX_TABLE (charpos);
 	      PREFETCH ();
@@ -4889,7 +4882,7 @@ re_match_2_internal (struct re_pattern_buffer *bufp,
 	      int c1, c2;
 	      int s1, s2;
 	      int dummy;
-              ptrdiff_t offset = PTR_TO_OFFSET (d);
+              ptrdiff_t offset = POINTER_TO_OFFSET (d);
               ptrdiff_t charpos = SYNTAX_TABLE_BYTE_TO_CHAR (offset) - 1;
 	      UPDATE_SYNTAX_TABLE (charpos);
 	      GET_CHAR_BEFORE_2 (c1, d, string1, end1, string2, end2);
@@ -4931,7 +4924,7 @@ re_match_2_internal (struct re_pattern_buffer *bufp,
 		 is the character at D, and S2 is the syntax of C2.  */
 	      int c1, c2;
 	      int s1, s2;
-	      ptrdiff_t offset = PTR_TO_OFFSET (d);
+	      ptrdiff_t offset = POINTER_TO_OFFSET (d);
 	      ptrdiff_t charpos = SYNTAX_TABLE_BYTE_TO_CHAR (offset);
 	      UPDATE_SYNTAX_TABLE (charpos);
 	      PREFETCH ();
@@ -4972,7 +4965,7 @@ re_match_2_internal (struct re_pattern_buffer *bufp,
 		 is the character at D, and S2 is the syntax of C2.  */
 	      int c1, c2;
 	      int s1, s2;
-              ptrdiff_t offset = PTR_TO_OFFSET (d);
+              ptrdiff_t offset = POINTER_TO_OFFSET (d);
               ptrdiff_t charpos = SYNTAX_TABLE_BYTE_TO_CHAR (offset) - 1;
 	      UPDATE_SYNTAX_TABLE (charpos);
 	      GET_CHAR_BEFORE_2 (c1, d, string1, end1, string2, end2);
@@ -5008,7 +5001,7 @@ re_match_2_internal (struct re_pattern_buffer *bufp,
 			 mcnt);
 	    PREFETCH ();
 	    {
-	      ptrdiff_t offset = PTR_TO_OFFSET (d);
+	      ptrdiff_t offset = POINTER_TO_OFFSET (d);
 	      ptrdiff_t pos1 = SYNTAX_TABLE_BYTE_TO_CHAR (offset);
 	      UPDATE_SYNTAX_TABLE (pos1);
 	    }
diff --git a/src/syntax.h b/src/syntax.h
index aefe4dafa42..05d58eff05f 100644
--- a/src/syntax.h
+++ b/src/syntax.h
@@ -145,7 +145,7 @@ extern bool syntax_prefix_flag_p (int c);
 
 extern unsigned char const syntax_spec_code[0400];
 
-/* Convert the byte offset BYTEPOS into a character position,
+/* Convert the regexp BYTEOFFSET into a character position,
    for the object recorded in gl_state with SETUP_SYNTAX_TABLE_FOR_OBJECT.
 
    The value is meant for use in code that does nothing when
@@ -153,19 +153,19 @@ extern unsigned char const syntax_spec_code[0400];
    for speed.  */
 
 INLINE ptrdiff_t
-SYNTAX_TABLE_BYTE_TO_CHAR (ptrdiff_t bytepos)
+SYNTAX_TABLE_BYTE_TO_CHAR (ptrdiff_t byteoffset)
 {
   return (! parse_sexp_lookup_properties
 	  ? 0
 	  : STRINGP (gl_state.object)
-	  ? string_byte_to_char (gl_state.object, bytepos)
+	  ? string_byte_to_char (gl_state.object, byteoffset)
 	  : BUFFERP (gl_state.object)
 	  ? ((buf_bytepos_to_charpos
 	      (XBUFFER (gl_state.object),
-	       (bytepos + BUF_BEGV_BYTE (XBUFFER (gl_state.object)) - 1))))
+	       (byteoffset + BUF_BEGV_BYTE (XBUFFER (gl_state.object))))))
 	  : NILP (gl_state.object)
-	  ? BYTE_TO_CHAR (bytepos + BEGV_BYTE - 1)
-	  : bytepos);
+	  ? BYTE_TO_CHAR (byteoffset + BEGV_BYTE)
+	  : byteoffset);
 }
 
 /* Make syntax table state (gl_state) good for CHARPOS, assuming it is