From 14150241cfd016c7f64974cc5c58bb116689f3c1 Mon Sep 17 00:00:00 2001
From: Emilio Jesus Gallego Arias
Date: Thu, 2 Jul 2020 18:17:24 +0200
Subject: [vernac] Allow to control typing flags with attributes.

The syntax is the one of boolean attributes, that is to say
`#[typing($flag={yes,no}]` where `$flag` is one of `guarded`,
`universes`, `positive`.

We had to instrument the pretyper in a few places, it is interesting
that it is doing so many checks.
---
 doc/sphinx/language/core/inductive.rst          | 26 +++++++++++--------------
 doc/sphinx/proof-engine/vernacular-commands.rst | 15 ++++++++++++++
 2 files changed, 26 insertions(+), 15 deletions(-)

(limited to 'doc/sphinx')

diff --git a/doc/sphinx/language/core/inductive.rst b/doc/sphinx/language/core/inductive.rst
index 9fda2ab1fa..f277997094 100644
--- a/doc/sphinx/language/core/inductive.rst
+++ b/doc/sphinx/language/core/inductive.rst
@@ -31,8 +31,8 @@ Inductive types
    proposition).
 
    This command supports the :attr:`universes(polymorphic)`,
-   :attr:`universes(template)`, :attr:`universes(cumulative)`, and
-   :attr:`private(matching)` attributes.
+   :attr:`universes(template)`, :attr:`universes(cumulative)`,
+   :attr:`typing(positive)`, and :attr:`private(matching)` attributes.
 
    Mutually inductive types can be defined by including multiple :n:`@inductive_definition`\s.
    The :n:`@ident`\s are simultaneously added to the environment before the types of constructors are checked.
@@ -49,10 +49,12 @@ Inductive types
 
    .. exn:: Non strictly positive occurrence of @ident in @type.
 
-      The types of the constructors have to satisfy a *positivity condition*
-      (see Section :ref:`positivity`). This condition ensures the soundness of
-      the inductive definition. The positivity checking can be disabled using
-      the :flag:`Positivity Checking` flag (see :ref:`controlling-typing-flags`).
+      The types of the constructors have to satisfy a *positivity
+      condition* (see Section :ref:`positivity`). This condition
+      ensures the soundness of the inductive definition. The
+      positivity checking can be disabled using the :flag:`Positivity
+      Checking` flag or the :attr:`typing(positive)` attribute (see
+      :ref:`controlling-typing-flags`).
 
    .. exn:: The conclusion of @type is not valid; it must be built from @ident.
 
@@ -848,9 +850,7 @@ between universes for inductive types in the Type hierarchy.
 
    .. coqtop:: none
 
-      Unset Positivity Checking.
-      Inductive I : Prop := not_I_I (not_I : I -> False) : I.
-      Set Positivity Checking.
+      #[typing(positive=no)] Inductive I : Prop := not_I_I (not_I : I -> False) : I.
 
    .. coqtop:: all
 
@@ -884,9 +884,7 @@ between universes for inductive types in the Type hierarchy.
 
    .. coqtop:: none
 
-      Unset Positivity Checking.
-      Inductive Lam := lam (_ : Lam -> Lam).
-      Set Positivity Checking.
+      #[typing(positive=no)] Inductive Lam := lam (_ : Lam -> Lam).
 
    .. coqtop:: all
 
@@ -915,9 +913,7 @@ between universes for inductive types in the Type hierarchy.
 
    .. coqtop:: none
 
-      Unset Positivity Checking.
-      Inductive A: Type := introA: ((A -> Prop) -> Prop) -> A.
-      Set Positivity Checking.
+      #[typing(positive=no)] Inductive A: Type := introA: ((A -> Prop) -> Prop) -> A.
 
    .. coqtop:: all
 
diff --git a/doc/sphinx/proof-engine/vernacular-commands.rst b/doc/sphinx/proof-engine/vernacular-commands.rst
index e7db9cfaca..b8160b7966 100644
--- a/doc/sphinx/proof-engine/vernacular-commands.rst
+++ b/doc/sphinx/proof-engine/vernacular-commands.rst
@@ -1152,6 +1152,11 @@ Controlling Typing Flags
    anymore but it still affects the reduction of the term. Unchecked fixpoints are
    printed by :cmd:`Print Assumptions`.
 
+.. attr:: typing(guarded)
+
+   Similar to :flag:`Guard Checking`, but on a per-declaration
+   basis. Takes ``yes/no`` as parameters, i.e. ``typing(guarded=no)``.
+
 .. flag:: Positivity Checking
 
    This flag can be used to enable/disable the positivity checking of inductive
@@ -1159,6 +1164,11 @@ Controlling Typing Flags
    break the consistency of the system, use at your own risk. Unchecked
    (co)inductive types are printed by :cmd:`Print Assumptions`.
 
+.. attr:: typing(positive)
+
+   Similar to :flag:`Positivity Checking`, but on a per-declaration basis.
+   Takes ``yes/no`` as parameters, i.e. ``typing(positive=no)``.
+
 .. flag:: Universe Checking
 
    This flag can be used to enable/disable the checking of universes, providing a
@@ -1167,6 +1177,11 @@ Controlling Typing Flags
    :cmd:`Print Assumptions`. It has the same effect as `-type-in-type` command line
    argument (see :ref:`command-line-options`).
 
+.. attr:: typing(universes)
+
+   Similar to :flag:`Universe Checking`, but on a per-declaration basis.
+   Takes ``yes/no`` as parameters, i.e. ``typing(universes=no)``.
+
 .. cmd:: Print Typing Flags
 
    Print the status of the three typing flags: guard checking, positivity checking
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