fix(frontends/lean): type information for "atomic" notation declaration, fixes #292

src/frontends/lean/elaborator.cpp

@@ -132,7 +132,8 @@ optional<expr> elaborator::mvar_to_meta(expr const & mvar) {
 /** \brief Store the pair (pos(e), type(r)) in the info_data if m_info_manager is available. */
 void elaborator::save_type_data(expr const & e, expr const & r) {
     if (!m_no_info && infom() && pip() &&
-        (is_constant(e) || is_local(e) || is_placeholder(e) || is_as_atomic(e) || is_consume_args(e))) {
+        (is_constant(e) || is_local(e) || is_placeholder(e) || is_as_atomic(e) ||
+         is_consume_args(e) || is_notation_info(e))) {
         if (auto p = pip()->get_pos_info(e)) {
             expr t = m_tc[m_relax_main_opaque]->infer(r).first;
             m_pre_info_data.add_type_info(p->first, p->second, t);
@@ -862,6 +863,15 @@ pair<expr, constraint_seq> elaborator::visit(expr const & e) {
         save_extra_type_data(e, ecs.first);
         return ecs;
     }
+    if (is_notation_info(e)) {
+        pair<expr, constraint_seq> ecs;
+        {
+            flet<bool> let(m_no_info, true);
+            ecs = visit(get_annotation_arg(e));
+        }
+        save_type_data(e, ecs.first);
+        return ecs;
+    }
     expr r;
     expr b = e;
     constraint_seq cs;

src/frontends/lean/info_annotation.cpp

@@ -20,15 +20,25 @@ expr mk_extra_info(expr const & e, tag g) { return mk_annotation(get_extra_info(
 expr mk_extra_info(expr const & e) { return mk_annotation(get_extra_info(), e); }
 bool is_extra_info(expr const & e) { return is_annotation(e, get_extra_info()); }
 
+static name * g_notation_info = nullptr;
+name const & get_notation_info() { return *g_notation_info; }
+
+expr mk_notation_info(expr const & e, tag g) { return mk_annotation(get_notation_info(), e, g); }
+expr mk_notation_info(expr const & e) { return mk_annotation(get_notation_info(), e); }
+bool is_notation_info(expr const & e) { return is_annotation(e, get_notation_info()); }
+
 void initialize_info_annotation() {
     g_no_info = new name("no_info");
     register_annotation(*g_no_info);
     g_extra_info = new name("extra_info");
     register_annotation(*g_extra_info);
+    g_notation_info = new name("notation_info");
+    register_annotation(*g_notation_info);
 }
 
 void finalize_info_annotation() {
     delete g_no_info;
     delete g_extra_info;
+    delete g_notation_info;
 }
 }

src/frontends/lean/info_annotation.h

@@ -28,6 +28,16 @@ expr mk_extra_info(expr const & e);
 /** \brief Return true iff \c e is a term annotated with mk_extra_info */
 bool is_extra_info(expr const & e);
 
+/** \brief Annotate \c e with "notation-info" annotation.
+    It instructs the elaborator to store the type of \c e.
+    We use this feature to store the type of atomic notation (i.e.,
+    notation without parameters).
+*/
+expr mk_notation_info(expr const & e, tag g);
+expr mk_notation_info(expr const & e);
+/** \brief Return true iff \c e is a term annotated with mk_notation_info */
+bool is_notation_info(expr const & e);
+
 void initialize_info_annotation();
 void finalize_info_annotation();
 }

src/frontends/lean/parser.cpp

@@ -42,6 +42,7 @@ Author: Leonardo de Moura
 #include "frontends/lean/notation_cmd.h"
 #include "frontends/lean/elaborator.h"
 #include "frontends/lean/pp_options.h"
+#include "frontends/lean/info_annotation.h"
 
 #ifndef LEAN_DEFAULT_PARSER_SHOW_ERRORS
 #define LEAN_DEFAULT_PARSER_SHOW_ERRORS true
@@ -1002,7 +1003,13 @@ expr parser::parse_notation(parse_table t, expr * left) {
     }
     buffer<expr> cs;
     for (expr const & a : as) {
-        expr r = instantiate_rev(copy_with_new_pos(a, p), args.size(), args.data());
+        expr r = copy_with_new_pos(a, p);
+        if (args.empty()) {
+            // Notation does not have arguments. Thus, the info-manager should treat is as a single thing.
+            r = mk_notation_info(r, r.get_tag());
+        } else {
+            r = instantiate_rev(r, args.size(), args.data());
+        }
         cs.push_back(r);
     }
     expr r = save_pos(mk_choice(cs.size(), cs.data()), p);

tests/lean/interactive/notation_info.input

@@ -0,0 +1,8 @@
+VISIT notation_info.lean
+SYNC 4
+import data.nat
+open nat
+notation `one` := (succ 0)
+check one + one
+WAIT
+INFO 4

tests/lean/interactive/notation_info.input.expected.out

@@ -0,0 +1,22 @@
+-- BEGINWAIT
+-- ENDWAIT
+-- BEGININFO
+-- TYPE|4|6
+ℕ
+-- ACK
+-- SYMBOL|4|6
+one
+-- ACK
+-- TYPE|4|10
+ℕ → ℕ → ℕ
+-- ACK
+-- SYMBOL|4|10
++
+-- ACK
+-- TYPE|4|12
+ℕ
+-- ACK
+-- SYMBOL|4|12
+one
+-- ACK
+-- ENDINFO