Merge PR #12229: Hopefully consensual cleaning of keywords

Reviewed-by: Zimmi48
Reviewed-by: jfehrle
Ack-by: ppedrot

4 files changed, 41 insertions, 20 deletions

diff --git a/doc/sphinx/language/coq-library.rst b/doc/sphinx/language/coq-library.rst
index acdd4408ed..899173a83a 100644
--- a/doc/sphinx/language/coq-library.rst
+++ b/doc/sphinx/language/coq-library.rst
@@ -9,11 +9,11 @@ The |Coq| library
 
 The |Coq| library has two parts:
 
-  * **The basic library**: definitions and theorems for
+  * The :gdef:`prelude`: definitions and theorems for
     the most commonly used elementary logical notions and
     data types. |Coq| normally loads these files automatically when it starts.
 
-  * **The standard library**: general-purpose libraries with
+  * The :gdef:`standard library`: general-purpose libraries with
     definitions and theorems for sets, lists, sorting,
     arithmetic, etc. To use these files, users must load them explicitly
     with the ``Require`` command (see :ref:`compiled-files`)
@@ -28,8 +28,8 @@ also be browsed at http://coq.inria.fr/stdlib/.
 
 
 
-The basic library
------------------
+The prelude
+-----------
 
 This section lists the basic notions and results which are directly
 available in the standard |Coq| system. Most of these constructions
diff --git a/doc/sphinx/language/core/basic.rst b/doc/sphinx/language/core/basic.rst
index 9473cc5a15..aa93b4d21f 100644
--- a/doc/sphinx/language/core/basic.rst
+++ b/doc/sphinx/language/core/basic.rst
@@ -130,30 +130,37 @@ Strings
   identified with :production:`string`.
 
 Keywords
-  The following character sequences are reserved keywords that cannot be
-  used as identifiers::
+  The following character sequences are keywords defined in the main Coq grammar
+  that cannot be used as identifiers (even when starting Coq with the `-noinit`
+  command-line flag)::
 
     _ Axiom CoFixpoint Definition Fixpoint Hypothesis Parameter Prop
-    SProp Set Theorem Type Variable as at cofix discriminated else end
+    SProp Set Theorem Type Variable as at cofix else end
     fix for forall fun if in let match return then where with
 
-  Note that notations and plugins may define additional keywords.
+  The following are keywords defined in notations or plugins loaded in the :term:`prelude`::
 
-Other tokens
-  The set of
-  tokens defined at any given time can vary because the :cmd:`Notation`
-  command can define new tokens.  A :cmd:`Require` command may load more notation definitions,
-  while the end of a :cmd:`Section` may remove notations.  Some notations
-  are defined in the standard library (see :ref:`thecoqlibrary`) and are generally
-  loaded automatically at startup time.
+    IF by exists exists2 using
+
+  Note that loading additional modules or plugins may expand the set of reserved
+  keywords.
 
-  Here are the character sequences that |Coq| directly defines as tokens
-  without using :cmd:`Notation`::
+Other tokens
+  The following character sequences are tokens defined in the main Coq grammar
+  (even when starting Coq with the `-noinit` command-line flag)::
 
-    ! #[ % & ' ( () (bfs) (dfs) ) * ** + , - ->
+    ! #[ % & ' ( () ) * + , - ->
     . .( .. ... / : ::= := :> :>> ; < <+ <- <:
-    <<: <= = => > >-> >= ? @ @{ [ [= ] _
-    `( `{ { {| | |- || }
+    <<: <= = => > >-> >= ? @ @{ [ ] _
+    `( `{ { {| | }
+
+  The following character sequences are tokens defined in notations or plugins
+  loaded in the :term:`prelude`::
+
+    ** [= |- || ->
+
+  Note that loading additional modules or plugins may expand the set of defined
+  tokens.
 
   When multiple tokens match the beginning of a sequence of characters,
   the longest matching token is used.
diff --git a/doc/sphinx/proof-engine/ltac.rst b/doc/sphinx/proof-engine/ltac.rst
index b184311bef..90173d65bf 100644
--- a/doc/sphinx/proof-engine/ltac.rst
+++ b/doc/sphinx/proof-engine/ltac.rst
@@ -57,6 +57,8 @@ mode but it can also be used in toplevel definitions as shown below.
 
 .. note::
 
+   - The grammar reserves the token ``||``.
+
    - The infix tacticals  ``… || …`` ,  ``… + …`` , and  ``… ; …``  are associative.
 
      .. example::
diff --git a/doc/sphinx/proof-engine/tactics.rst b/doc/sphinx/proof-engine/tactics.rst
index 439f7fb9f6..127e4c6dbe 100644
--- a/doc/sphinx/proof-engine/tactics.rst
+++ b/doc/sphinx/proof-engine/tactics.rst
@@ -36,6 +36,18 @@ language will be described in Chapter :ref:`ltac`.
 Common elements of tactics
 --------------------------
 
+Reserved keywords
+~~~~~~~~~~~~~~~~~
+
+The tactics described in this chapter reserve the following keywords::
+
+  by using
+
+Thus, these keywords cannot be used as identifiers. It also declares
+the following character sequences as tokens::
+
+  ** [= |-
+
 .. _invocation-of-tactics:
 
 Invocation of tactics