feat(frontends/lean): provide 'partial' type information even when there are type errors

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>

src/frontends/lean/elaborator.cpp

@@ -1302,19 +1302,9 @@ public:
     void copy_info_to_manager(substitution s) {
         if (!m_info_manager)
             return;
-        for (auto & p : m_pre_info_data) {
+        for (auto & p : m_pre_info_data)
             p = type_info_data(p.get_line(), p.get_column(), s.instantiate(p.get_type()));
-        }
+        m_info_manager->append(m_pre_info_data);
-        std::stable_sort(m_pre_info_data.begin(), m_pre_info_data.end());
-        type_info_data prev;
-        bool first = true;
-        for (auto const & p : m_pre_info_data) {
-            if (first || !p.eq_pos(prev.get_line(), prev.get_column())) {
-                m_info_manager->add(std::unique_ptr<info_data>(new type_info_data(p)));
-                prev  = p;
-                first = false;
-            }
-        }
     }
 
     std::tuple<expr, level_param_names> operator()(expr const & e, bool _ensure_type, bool relax_main_opaque) {

src/frontends/lean/info_manager.cpp

@@ -115,6 +115,20 @@ void info_manager::append(std::vector<std::unique_ptr<info_data>> && v) {
         add_core(std::move(d));
 }
 
+void info_manager::append(std::vector<type_info_data> & v, bool remove_duplicates) {
+    lock_guard<mutex> lc(m_mutex);
+    std::stable_sort(v.begin(), v.end());
+    type_info_data prev;
+    bool first = true;
+    for (auto const & p : v) {
+        if (!remove_duplicates || first || !p.eq_pos(prev.get_line(), prev.get_column())) {
+            add_core(std::unique_ptr<info_data>(new type_info_data(p)));
+            prev  = p;
+            first = false;
+        }
+    }
+}
+
 void info_manager::sort() {
     lock_guard<mutex> lc(m_mutex);
     sort_core();

src/frontends/lean/info_manager.h

@@ -62,6 +62,7 @@ public:
     void invalidate(unsigned sline);
     void add(std::unique_ptr<info_data> && d);
     void append(std::vector<std::unique_ptr<info_data>> && v);
+    void append(std::vector<type_info_data> & v, bool remove_duplicates = true);
     void sort();
     void display(io_state_stream const & ios, unsigned line);
 };

src/frontends/lean/parser.cpp

@@ -507,8 +507,10 @@ std::tuple<expr, level_param_names> parser::elaborate_relaxed(expr const & e, li
     bool relax            = true;
     bool check_unassigned = false;
     bool ensure_type      = false;
-    return ::lean::elaborate(m_env, m_local_level_decls, ctx, m_ios, e, relax, &pp, check_unassigned, ensure_type,
+    auto r = ::lean::elaborate(m_env, m_local_level_decls, ctx, m_ios, e, relax, &pp, check_unassigned, ensure_type,
-                             m_info_manager);
+                               m_info_manager);
+    m_pre_info_data.clear();
+    return r;
 }
 
 std::tuple<expr, level_param_names> parser::elaborate_type(expr const & e, list<expr> const & ctx) {
@@ -516,25 +518,33 @@ std::tuple<expr, level_param_names> parser::elaborate_type(expr const & e, list<
     bool relax            = false;
     bool check_unassigned = true;
     bool ensure_type      = true;
-    return ::lean::elaborate(m_env, m_local_level_decls, ctx, m_ios, e, relax, &pp, check_unassigned, ensure_type,
+    auto r = ::lean::elaborate(m_env, m_local_level_decls, ctx, m_ios, e, relax, &pp, check_unassigned, ensure_type,
-                             m_info_manager);
+                               m_info_manager);
+    m_pre_info_data.clear();
+    return r;
 }
 
 std::tuple<expr, level_param_names> parser::elaborate_at(environment const & env, expr const & e) {
     parser_pos_provider pp = get_pos_provider();
     bool relax            = false;
-    return ::lean::elaborate(env, m_local_level_decls, list<expr>(), m_ios, e, relax, &pp, m_info_manager);
+    auto r = ::lean::elaborate(env, m_local_level_decls, list<expr>(), m_ios, e, relax, &pp, m_info_manager);
+    m_pre_info_data.clear();
+    return r;
 }
 
 std::tuple<expr, expr, level_param_names> parser::elaborate_definition(name const & n, expr const & t, expr const & v, bool is_opaque) {
     parser_pos_provider pp = get_pos_provider();
-    return ::lean::elaborate(m_env, m_local_level_decls, m_ios, n, t, v, is_opaque, &pp, m_info_manager);
+    auto r = ::lean::elaborate(m_env, m_local_level_decls, m_ios, n, t, v, is_opaque, &pp, m_info_manager);
+    m_pre_info_data.clear();
+    return r;
 }
 
 std::tuple<expr, expr, level_param_names> parser::elaborate_definition_at(environment const & env, local_level_decls const & lls,
                                                                           name const & n, expr const & t, expr const & v, bool is_opaque) {
     parser_pos_provider pp = get_pos_provider();
-    return ::lean::elaborate(env, lls, m_ios, n, t, v, is_opaque, &pp, m_info_manager);
+    auto r = ::lean::elaborate(env, lls, m_ios, n, t, v, is_opaque, &pp, m_info_manager);
+    m_pre_info_data.clear();
+    return r;
 }
 
 [[ noreturn ]] void throw_invalid_open_binder(pos_info const & pos) {
@@ -842,6 +852,7 @@ expr parser::parse_notation(parse_table t, expr * left) {
     }
     expr r = save_pos(mk_choice(cs.size(), cs.data()), p);
     save_overload(r);
+    save_type_info(r);
     return r;
 }
 
@@ -870,18 +881,26 @@ expr parser::id_to_expr(name const & id, pos_info const & p) {
 
     if (id.is_atomic()) {
         // locals
-        if (auto it1 = m_local_decls.find(id))
+        if (auto it1 = m_local_decls.find(id)) {
-            return copy_with_new_pos(propagate_levels(*it1, ls), p);
+            auto r = copy_with_new_pos(propagate_levels(*it1, ls), p);
+            save_type_info(r);
+            return r;
+        }
     } else {
         lean_assert(!id.is_atomic());
         name new_id = remove_root_prefix(id);
         if (m_env.find(new_id)) {
-            return save_pos(mk_constant(new_id, ls), p);
+            auto r = save_pos(mk_constant(new_id, ls), p);
+            save_type_info(r);
+            return r;
         } else {
             for (name const & ns : get_namespaces(m_env)) {
                 auto new_id = ns + id;
-                if (m_env.find(new_id))
+                if (m_env.find(new_id)) {
-                    return save_pos(mk_constant(new_id, ls), p);
+                    auto r = save_pos(mk_constant(new_id, ls), p);
+                    save_type_info(r);
+                    return r;
+                }
             }
         }
     }
@@ -906,6 +925,7 @@ expr parser::id_to_expr(name const & id, pos_info const & p) {
         r = save_pos(mk_constant(get_namespace(m_env) + id, ls), p);
     if (!r)
         throw parser_error(sstream() << "unknown identifier '" << id << "'", p);
+    save_type_info(*r);
     return *r;
 }
 
@@ -1176,6 +1196,11 @@ void parser::save_snapshot() {
         return;
     if (m_snapshot_vector->empty() || static_cast<int>(m_snapshot_vector->back().m_line) != m_scanner.get_line())
         m_snapshot_vector->push_back(snapshot(m_env, m_local_level_decls, m_local_decls, m_ios.get_options(), m_scanner.get_line()));
+    // if elaborator failed, then m_pre_info_data contains type information before elaboration.
+    if (m_info_manager) {
+        m_info_manager->append(m_pre_info_data, false);
+        m_pre_info_data.clear();
+    }
 }
 
 void parser::save_overload(expr const & e) {
@@ -1185,6 +1210,33 @@ void parser::save_overload(expr const & e) {
     m_info_manager->add(std::unique_ptr<info_data>(new overload_info_data(p.first, p.second, e)));
 }
 
+void parser::save_type_info(expr const & e) {
+    if (!m_info_manager)
+        return;
+    if (is_explicit(e)) {
+        save_type_info(get_explicit_arg(e));
+    } else if (is_implicit(e)) {
+        save_type_info(get_implicit_arg(e));
+    } else if (is_choice(e)) {
+        for (unsigned i = 0; i < get_num_choices(e); i++)
+            save_type_info(get_choice(e, i));
+    } else if (is_app(e)) {
+        save_type_info(get_app_fn(e));
+    } else if (is_constant(e)) {
+        auto d = m_env.find(const_name(e));
+        if (!d)
+            return;
+        auto p = pos_of(e);
+        m_pre_info_data.push_back(type_info_data(p.first, p.second, d->get_type()));
+    } else if (is_local(e)) {
+        auto p = pos_of(e);
+        expr t = mlocal_type(e);
+        if (is_meta(t))
+            return;
+        m_pre_info_data.push_back(type_info_data(p.first, p.second, t));
+    }
+}
+
 bool parse_commands(environment & env, io_state & ios, std::istream & in, char const * strm_name, bool use_exceptions,
                     unsigned num_threads) {
     parser p(env, ios, in, strm_name, use_exceptions, num_threads);

src/frontends/lean/parser.h

@@ -88,6 +88,7 @@ class parser {
     // info support
     snapshot_vector *       m_snapshot_vector;
     info_manager *          m_info_manager;
+    std::vector<type_info_data> m_pre_info_data; // type information before elaboration
 
     void display_warning_pos(unsigned line, unsigned pos);
     void display_warning_pos(pos_info p);
@@ -154,6 +155,7 @@ class parser {
 
     void save_snapshot();
     void save_overload(expr const & e);
+    void save_type_info(expr const & e);
 
 public:
     parser(environment const & env, io_state const & ios,