From 857e9ff0a7927d370c8a16e723385a9b199de872 Mon Sep 17 00:00:00 2001
From: Guillaume Melquiond
Date: Mon, 2 May 2016 16:54:38 +0200
Subject: Properly handle notations containing spaces (bug #4538).

When a notation was starting or ending a space, Coq assumed the notation
had no terminal symbol in either places. Coq also considered a notation
containing only spaces to be productive. As stated in the documentation,
extraneous spaces are only meant as printing hints, they are not meant to
have any influence on parsing.
---
 test-suite/bugs/closed/4538.v |  1 +
 toplevel/metasyntax.ml        | 23 +++++++++++++++++------
 2 files changed, 18 insertions(+), 6 deletions(-)
 create mode 100644 test-suite/bugs/closed/4538.v

diff --git a/test-suite/bugs/closed/4538.v b/test-suite/bugs/closed/4538.v
new file mode 100644
index 0000000000..f925aae9e5
--- /dev/null
+++ b/test-suite/bugs/closed/4538.v
@@ -0,0 +1 @@
+Reserved Notation "   (u *)   ".
diff --git a/toplevel/metasyntax.ml b/toplevel/metasyntax.ml
index 231b22e255..2ccd27acb9 100644
--- a/toplevel/metasyntax.ml
+++ b/toplevel/metasyntax.ml
@@ -1002,7 +1002,7 @@ let make_interpretation_vars recvars allvars =
     (sc, make_interpretation_type (Id.List.mem_assoc x recvars) typ)) mainvars
 
 let check_rule_productivity l =
-  if List.for_all (function NonTerminal _ -> true | _ -> false) l then
+  if List.for_all (function NonTerminal _ | Break _ -> true | _ -> false) l then
     error "A notation must include at least one symbol.";
   if (match l with SProdList _ :: _ -> true | _ -> false) then
     error "A recursive notation must start with at least one symbol."
@@ -1020,8 +1020,21 @@ let is_not_printable onlyparse noninjective = function
   else onlyparse
 
 let find_precedence lev etyps symbols =
-  match symbols with
-  | NonTerminal x :: _ ->
+  let first_symbol =
+    let rec aux = function
+      | Break _ :: t -> aux t
+      | h :: t -> h
+      | [] -> assert false (* rule is known to be productive *) in
+    aux symbols in
+  let last_is_terminal () =
+    let rec aux b = function
+      | Break _ :: t -> aux b t
+      | Terminal _ :: t -> aux true t
+      | _ :: t -> aux false t
+      | [] -> b in
+    aux false symbols in
+  match first_symbol with
+  | NonTerminal x ->
       (try match List.assoc x etyps with
 	| ETConstr _ ->
 	    error "The level of the leftmost non-terminal cannot be changed."
@@ -1044,9 +1057,7 @@ let find_precedence lev etyps symbols =
 	if Option.is_empty lev then
 	  error "A left-recursive notation must have an explicit level."
 	else [],Option.get lev)
-  | Terminal _ ::l when
-      (match List.last symbols with Terminal _ -> true |_ -> false)
-      ->
+  | Terminal _ when last_is_terminal () ->
       if Option.is_empty lev then
 	([msg_info,strbrk "Setting notation at level 0."], 0)
       else [],Option.get lev
-- 
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