flymake-error-bitmap

flymake-error-bitmap is a variable defined in `flymake.el'.
Its value is

(exclamation-mark error)

Documentation:
Bitmap (a symbol) used in the fringe for indicating errors.
The value may also be a list of two elements where the second
element specifies the face for the bitmap. For possible bitmap
symbols, see `fringe-bitmaps'. See also `flymake-warning-bitmap'.

The option `flymake-fringe-indicator-position' controls how and where
this is used.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 24.3 of Emacs.