In printing, factorizing "match" clauses with same right-hand side.

Moreover, when there are at least two clauses and the last most
factorizable one is a disjunction with no variables, turn it into a
catch-all clause.

Adding options

  Unset Printing Allow Default Clause.

to deactivate the second behavior, and

  Unset Printing Factorizable Match Patterns.

to deactivate the first behavior (deactivating the first one
deactivates also the second one).

E.g. printing

  match x with Eq => 1 | _ => 0 end

gives

  match x with
  | Eq => 1
  | _ => 0
  end

or (with default clause deactivates):

  match x with
  | Eq => 1
  | Lt | Gt => 0
  end

More to be done, e.g. reconstructing multiple patterns in Nat.eqb...

1 files changed, 32 insertions, 0 deletions

diff --git a/test-suite/output/Cases.v b/test-suite/output/Cases.v
index 17fee3303..caf3b2870 100644
--- a/test-suite/output/Cases.v
+++ b/test-suite/output/Cases.v
@@ -1,5 +1,7 @@
 (* Cases with let-in in constructors types *)
 
+Unset Printing Allow Match Default Clause.
+
 Inductive t : Set :=
     k : let x := t in x -> x.
 
@@ -184,3 +186,33 @@ let p := fresh "p" in
   |- eq_refl ?p = _ => pose (match eq_refl p in _ = z return p=p /\ z=z with eq_refl => conj eq_refl eq_refl end)
   end.
 Show.
+
+Set Printing Allow Match Default Clause.
+
+(***************************************************)
+(* Testing strategy for factorizing cases branches *)
+
+(* Factorization + default clause *)
+Check fun x => match x with Eq => 1 | _ => 0 end.
+
+(* No factorization *)
+Unset Printing Factorizable Match Patterns.
+Check fun x => match x with Eq => 1 | _ => 0 end.
+Set Printing Factorizable Match Patterns.
+
+(* Factorization but no default clause *)
+Unset Printing Allow Match Default Clause.
+Check fun x => match x with Eq => 1 | _ => 0 end.
+Set Printing Allow Match Default Clause.
+
+(* No factorization in printing all mode *)
+Set Printing All.
+Check fun x => match x with Eq => 1 | _ => 0 end.
+Unset Printing All.
+
+(* Several clauses *)
+Inductive K := a1|a2|a3|a4|a5|a6.
+Check fun x => match x with a3 | a4 => 3 | _ => 2 end.
+Check fun x => match x with a3 => 3 | a2 | a1 => 4 | _ => 2 end.
+Check fun x => match x with a4 => 3 | a2 | a1 => 4 | _ => 2 end.
+Check fun x => match x with a3 | a4 | a1 => 3 | _ => 2 end.