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authorMatthew Pickering <matthewtpickering@gmail.com>2018-01-15 12:37:51 -0500
committerBen Gamari <ben@smart-cactus.org>2018-01-15 13:53:45 -0500
commitd1ac1c337c5d200fe8a885b42d334c74fb083c2e (patch)
treeec54d5f5249d1e6e232637205b3b26dcfc4c796e /docs/users_guide
parenta770226e03f09b767fdb4ce826162a5c0f29ec29 (diff)
downloadhaskell-d1ac1c337c5d200fe8a885b42d334c74fb083c2e.tar.gz
Rename -frule-check to -drule-check and document
Reviewers: bgamari Reviewed By: bgamari Subscribers: rwbarton, thomie, carter Differential Revision: https://phabricator.haskell.org/D4256
Diffstat (limited to 'docs/users_guide')
-rw-r--r--docs/users_guide/debugging.rst13
1 files changed, 13 insertions, 0 deletions
diff --git a/docs/users_guide/debugging.rst b/docs/users_guide/debugging.rst
index efa6e2808d..399791925c 100644
--- a/docs/users_guide/debugging.rst
+++ b/docs/users_guide/debugging.rst
@@ -270,6 +270,19 @@ subexpression elimination pass.
Dumps detailed information about all rules that fired in this
module
+.. ghc-flag:: -drule-check=⟨str⟩
+ :shortdesc: Dump information about potential rule application
+ :type: dynamic
+
+ This flag is useful for debugging why a rule you expect to be firing isn't.
+
+ Rules are filtered by the user provided string, a rule is kept if a prefix
+ of its name matches the string.
+ The pass then checks whether any of these rules could apply to
+ the program but which didn't file for some reason. For example, specifying
+ ``-drule-check=SPEC`` will check whether there are any applications which
+ might be subject to a rule created by specialisation.
+
.. ghc-flag:: -ddump-vect
:shortdesc: Dump vectoriser input and output
:type: dynamic