PostgreSQL and Flymake

Flymake is an on-the-fly syntax checker for Emacs. Here is how you can use it for editing the PostgreSQL source code. Add this to your src/Makefile.custom:

check-syntax:
        $(COMPILE.c) -fsyntax-only $(CHK_SOURCES)

Then you can activate the flymake minor mode either manually using M-x flymake-mode, or by adding it to your Emacs customization for PostgreSQL. I use:

(defun pgsql-c-mode ()
  "C mode adjusted for PostgreSQL project"
  (interactive)
  (c-mode)
  (flymake-mode)

  ; .. and the rest ...
)

Here is a screenshot:

Notice the marked line with the syntax error and the tooltip/popup with the error message, which appears when the mouse hovers over the marked line.

Note, however, that since activating flymake will essentially cause a compiler to be running continuously in the background, this is not what you want to use when hacking PostgreSQL on the road. ;-)