Add matching error-offset output to pcre2test for substitute (#757)

Author: NWilson

src/pcre2_substitute.c

@@ -129,7 +129,6 @@ for (; ptr < ptrend; ptr++)
     ptr += 1;  /* Must point after \ */
     erc = PRIV(check_escape)(&ptr, ptrend, &ch, &errorcode,
       code->overall_options, code->extra_options, code->top_bracket, FALSE, NULL);
-    ptr -= 1;  /* Back to last code unit of escape */
     if (errorcode != 0)
       {
       /* errorcode from check_escape is positive, so must not be returned by

src/pcre2test.c

@@ -8987,6 +8987,25 @@ if (dat_datctl.replacement[0] != 0)
     if (rc == PCRE2_ERROR_NOMEMORY &&
         (xoptions & PCRE2_SUBSTITUTE_OVERFLOW_LENGTH) != 0)
       fprintf(outfile, ": %ld code units are needed", (long int)nsize);
+
+    if (rc != PCRE2_ERROR_NOMEMORY && nsize != PCRE2_UNSET)
+      {
+      PCRE2_SIZE full_rlen = (rlen != PCRE2_ZERO_TERMINATED)? rlen :
+          STRLEN(rbptr);
+
+      fprintf(outfile, "\n        here: ");
+      if (nsize > 0)
+        {
+        PTRUNCV(rbptr, full_rlen, nsize, TRUE, utf, outfile);
+        fprintf(outfile, " ");
+        }
+      fprintf(outfile, "|<--|");
+      if (nsize < full_rlen)
+        {
+        fprintf(outfile, " ");
+        PTRUNCV(rbptr, full_rlen, nsize, FALSE, utf, outfile);
+        }
+      }
     }
   else
     {

testdata/testoutput10

@@ -2000,6 +2000,7 @@ Failed: error 151 at offset 4: octal value is greater than \377 in 8-bit non-UTF
 /abc/substitute_extended
     abc\=replace=\400
 Failed: error -57 at offset 4 in replacement: bad escape sequence in replacement string
+        here: \400 |<--|
 
 /\400/python_octal
 Failed: error 202 at offset 4: octal value given by \ddd is greater than \377 (forbidden by PCRE2_EXTRA_PYTHON_OCTAL)
@@ -2008,6 +2009,7 @@ Failed: error 202 at offset 4: octal value given by \ddd is greater than \377 (f
 /abc/substitute_extended,python_octal
     abc\=replace=\400
 Failed: error -57 at offset 4 in replacement: bad escape sequence in replacement string
+        here: \400 |<--|
 
 /\400/utf
 
@@ -2022,6 +2024,7 @@ Failed: error 202 at offset 4: octal value given by \ddd is greater than \377 (f
 /abc/utf,substitute_extended,python_octal
     abc\=replace=\400
 Failed: error -57 at offset 4 in replacement: bad escape sequence in replacement string
+        here: \400 |<--|
 
 /[\x00-\x2f\x11-\xff]+/B
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