Re: bug#24483: 25.1; sql-mode error due to nil prompt-cont-regexp

[Nesa K]

On Tuesday, September 20, 2016 at 1:50:11 PM UTC-4, Michael Kleehammer wrote:
> It looks like sql-interactive-remove-continuation-prompt needs to explicitly 
> check for a nil sql-prompt-cont-regexp, which is the default value for some 
> SQL products.
> 
> In particular, this line marked with an arrow on the left needs a guard:
> 
>     (when (and comint-prompt-regexp
>                (or (> (length (or sql-preoutput-hold "")) 0)
>                    (> (or sql-output-newline-count 0) 0)
>                    (not (or (string-match sql-prompt-regexp oline)
>     -->                     (string-match sql-prompt-cont-regexp oline)))))
> 
> In my case I am using a custom "SQL product" for a SQL Server command
> line utility which prints "Connected to xyzzy\n" on startup but there
> are some standard "products" that also don't have a prompt-cont-regexp
> set.
> 
> It should be easy to reproduce using "ansi", but here is how I
> reproduced it with PostgreSQL:
> 
> 1) Set the PostgreSQL regexp to nil:
> 
>     (sql-set-product-feature 'postgres :prompt-cont-regexp nil)
> 
> 2) Make sure psql prints something on connect.  I have this in my
>    ~/.psqlrc:
> 
>     \pset null ¤
> 
> When you open a connection using sql-postgres you'll get:
> 
>     error in process filter: sql-interactive-remove-continuation-prompt: 
> Wrong type argument: stringp, nil
>     error in process filter: Wrong type argument: stringp, nil
> 
> This is new in 25.1.  I used 24.5 and did not have this issue. 
> 
> Thanks,
> Michael Kleehammer
> michael@kleehammer.com
> 
> 
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The bug is present in emacs version 25.3.1 as well. The same error happens if I 
use sql-ms mode. As Michael noted the error happens within 
sql-interactive-remove-continuation-prompt (oline) function at the line he 
marked with an arrow above. 

I was able to workaround the bug by overriding the function in my .emacs file 
with the following code:

(eval-after-load "sql"
  '(defun sql-interactive-remove-continuation-prompt (oline)
     "Strip out continuation prompts out of the OLINE.

Added to the `comint-preoutput-filter-functions' hook in a SQL
interactive buffer.  If `sql-output-newline-count' is greater than
zero, then an output line matching the continuation prompt is filtered
out.  If the count is zero, then a newline is inserted into the output
to force the output from the query to appear on a new line.

The complication to this filter is that the continuation prompts
may arrive in multiple chunks.  If they do, then the function
saves any unfiltered output in a buffer and prepends that buffer
to the next chunk to properly match the broken-up prompt.

If the filter gets confused, it should reset and stop filtering
to avoid deleting non-prompt output."

     ;; continue gathering lines of text iff
     ;;  + we know what a prompt looks like, and
     ;;  + there is held text, or
     ;;  + there are continuation prompt yet to come, or
     ;;  + not just a prompt string
     (when (and comint-prompt-regexp
                (or (> (length (or sql-preoutput-hold "")) 0)
                    (> (or sql-output-newline-count 0) 0)
                    (not (or (string-match sql-prompt-regexp oline)
                             (and sql-prompt-cont-regexp
                                  (string-match sql-prompt-cont-regexp 
oline))))))

       (save-match-data
         (let (prompt-found last-nl)

           ;; Add this text to what's left from the last pass
           (setq oline (concat sql-preoutput-hold oline)
                 sql-preoutput-hold "")

           ;; If we are looking for multiple prompts
           (when (and (integerp sql-output-newline-count)
                      (>= sql-output-newline-count 1))
             ;; Loop thru each starting prompt and remove it
             (let ((start-re (sql-starts-with-prompt-re)))
               (while (and (not (string= oline ""))
                           (> sql-output-newline-count 0)
                           (string-match start-re oline))
                 (setq oline (replace-match "" nil nil oline)
                       sql-output-newline-count (1- sql-output-newline-count)
                       prompt-found t)))

             ;; If we've found all the expected prompts, stop looking
             (if (= sql-output-newline-count 0)
                 (setq sql-output-newline-count nil
                       oline (concat "\n" oline))

               ;; Still more possible prompts, leave them for the next pass
               (setq sql-preoutput-hold oline
                     oline "")))

           ;; If no prompts were found, stop looking
           (unless prompt-found
             (setq sql-output-newline-count nil
                   oline (concat oline sql-preoutput-hold)
                   sql-preoutput-hold ""))

           ;; Break up output by physical lines if we haven't hit the final 
prompt
           (let ((end-re (sql-ends-with-prompt-re)))
             (unless (and (not (string= oline ""))
                          (string-match end-re oline)
                          (>= (match-end 0) (length oline)))
               ;; Find everything upto the last nl
               (setq last-nl 0)
               (while (string-match "\n" oline last-nl)
                 (setq last-nl (match-end 0)))
               ;; Hold after the last nl, return upto last nl
               (setq sql-preoutput-hold (concat (substring oline last-nl)
                                                sql-preoutput-hold)
                     oline (substring oline 0 last-nl)))))))
     oline))