Documenting the Shrink Abstract option.

3 files changed, 27 insertions, 0 deletions

diff --git a/CHANGES b/CHANGES
index 08484a4b9b..547ec8f9e3 100644
--- a/CHANGES
+++ b/CHANGES
@@ -23,6 +23,8 @@ Tactics
 - New compatibility flag "Universal Lemma Under Conjunction" which
   let tactics working under conjunctions apply sublemmas of the form
   "forall A, ... -> A".
+- New flag "Shrink Abstract" that minimalizes proofs generated by the abstract
+  tactical w.r.t. variables appearing in the body of the proof.
 
 API
 
diff --git a/doc/refman/RefMan-ltac.tex b/doc/refman/RefMan-ltac.tex
index d388840df5..7011f1ef89 100644
--- a/doc/refman/RefMan-ltac.tex
+++ b/doc/refman/RefMan-ltac.tex
@@ -1028,6 +1028,18 @@ This tactical is useful with tactics such as \texttt{omega} or
 the user can avoid the explosion at time of the \texttt{Save} command
 without having to cut manually the proof in smaller lemmas.
 
+It may be useful to generate lemmas minimal w.r.t. the assumptions they depend
+on. This can be obtained thanks to the option below.
+
+\begin{quote}
+\optindex{Shrink Abstract}
+{\tt Set Shrink Abstract}
+\end{quote}
+
+When set, all lemmas generated through \texttt{abstract {\tacexpr}} are
+quantified only over the variables that appear in the term constructed by
+\texttt{\tacexpr}.
+
 \begin{Variants}
 \item \texttt{abstract {\tacexpr} using {\ident}}.\\
   Give explicitly the name of the auxiliary lemma.
diff --git a/test-suite/success/shrink_abstract.v b/test-suite/success/shrink_abstract.v
new file mode 100644
index 0000000000..3f6b9cb39f
--- /dev/null
+++ b/test-suite/success/shrink_abstract.v
@@ -0,0 +1,13 @@
+Set Shrink Abstract.
+
+Definition foo : forall (n m : nat), bool.
+Proof.
+pose (p := 0).
+intros n.
+pose (q := n).
+intros m.
+pose (r := m).
+abstract (destruct m; [left|right]).
+Defined.
+
+Check (foo_subproof : nat -> bool).