fix(library/blast/subst): bug in subst action, add hypothesis_idx_buffer_set (helper class), refine revert_action interface

src/library/blast/hypothesis.h

@@ -47,4 +47,29 @@ public:
     bool depends_on(expr const & h) const { return m_deps.contains(href_index(h)); }
     bool is_assumption() const { return !m_value || is_local_non_href(*m_value); }
 };
+
+class hypothesis_idx_buffer_set {
+    friend class state;
+    hypothesis_idx_buffer m_buffer;
+    hypothesis_idx_set    m_set;
+public:
+    hypothesis_idx_buffer_set() {}
+    hypothesis_idx_buffer_set(hypothesis_idx_buffer const & b) {
+        for (auto hidx : b)
+            insert(hidx);
+    }
+
+    void insert(hypothesis_idx h) {
+        if (!m_set.contains(h)) {
+            m_set.insert(h);
+            m_buffer.push_back(h);
+        }
+    }
+    hypothesis_idx_buffer const & as_buffer() const {
+        return m_buffer;
+    }
+    hypothesis_idx_set const & as_set() const {
+        return m_set;
+    }
+};
 }}

src/library/blast/revert.cpp

@@ -23,26 +23,25 @@ struct revert_proof_step_cell : public proof_step_cell {
     virtual bool is_silent() const override { return true; }
 };
 
-unsigned revert_action(buffer<hypothesis_idx> & hidxs, hypothesis_idx_set & hidxs_set) {
-    lean_assert(hidxs.size() == hidxs_set.size());
+unsigned revert_action(hypothesis_idx_buffer_set & hidxs) {
     state & s = curr_state();
-    unsigned hidxs_size = hidxs.size();
+    unsigned hidxs_size = hidxs.as_buffer().size();
     for (unsigned i = 0; i < hidxs_size; i++) {
-        s.collect_forward_deps(hidxs[i], hidxs, hidxs_set);
+        s.collect_forward_deps(hidxs.as_buffer()[i], hidxs);
     }
     s.sort_hypotheses(hidxs);
     buffer<expr> hs;
-    s.to_hrefs(hidxs, hs);
+    s.to_hrefs(hidxs.as_buffer(), hs);
     expr target     = s.get_target();
     expr new_target = s.mk_pi(hs, target);
     s.set_target(new_target);
     s.push_proof_step(new revert_proof_step_cell(to_list(hs)));
-    lean_verify(s.del_hypotheses(hidxs));
-    return hidxs.size();
+    lean_verify(s.del_hypotheses(hidxs.as_buffer()));
+    return hidxs.as_buffer().size();
 }
 
 unsigned revert_action(buffer<hypothesis_idx> & hidxs) {
-    hypothesis_idx_set hidxs_set(hidxs);
-    return revert_action(hidxs, hidxs_set);
+    hypothesis_idx_buffer_set _hidxs(hidxs);
+    return revert_action(_hidxs);
 }
 }}

src/library/blast/revert.h

@@ -12,8 +12,5 @@ namespace blast {
 /** \brief Revert the given hypotheses and their dependencies.
     Return the total number of hypotheses reverted. */
 unsigned revert_action(buffer<hypothesis_idx> & hidxs);
-
-/** \brief Lower-level version of previous procedure.
-    \pre hidxs and hidxs_set contain the same elements. */
-unsigned revert_action(buffer<hypothesis_idx> & hidxs, hypothesis_idx_set & hidxs_set);
+unsigned revert_action(hypothesis_idx_buffer_set & hidxs);
 }}

src/library/blast/state.cpp

@@ -363,6 +363,10 @@ void state::sort_hypotheses(hypothesis_idx_buffer & r) const {
     std::sort(r.begin(), r.end(), hypothesis_dep_depth_lt(*this));
 }
 
+void state::sort_hypotheses(hypothesis_idx_buffer_set & r) const {
+    std::sort(r.m_buffer.begin(), r.m_buffer.end(), hypothesis_dep_depth_lt(*this));
+}
+
 void state::to_hrefs(hypothesis_idx_buffer const & hidxs, buffer<expr> & r) const {
     for (hypothesis_idx hidx : hidxs)
         r.push_back(get_hypothesis_decl(hidx)->get_self());
@@ -485,19 +489,15 @@ void state::del_hypotheses(buffer<hypothesis_idx> const & to_delete, hypothesis_
     }
 }
 
-void state::collect_forward_deps(hypothesis_idx hidx, buffer<hypothesis_idx> & result, hypothesis_idx_set & already_found) {
-    unsigned qhead = result.size();
+void state::collect_forward_deps(hypothesis_idx hidx, hypothesis_idx_buffer_set & result) {
+    hypothesis_idx_buffer const & b = result.as_buffer();
+    unsigned qhead = b.size();
     while (true) {
-        hypothesis_idx_set s = get_forward_deps(hidx);
-        s.for_each([&](hypothesis_idx h_dep) {
-                if (already_found.contains(h_dep))
-                    return;
-                already_found.insert(h_dep);
-                result.push_back(h_dep);
-            });
-        if (qhead == result.size())
+        hypothesis_idx_set s = get_direct_forward_deps(hidx);
+        s.for_each([&](hypothesis_idx h_dep) { result.insert(h_dep); });
+        if (qhead == b.size())
             return;
-        hidx = result[qhead];
+        hidx = b[qhead];
         qhead++;
     }
 }
@@ -514,38 +514,29 @@ bool state::safe_to_delete(buffer<hypothesis_idx> const & to_delete) {
     return true;
 }
 
-void state::collect_forward_deps(hypothesis_idx hidx, buffer<hypothesis_idx> & result) {
-    hypothesis_idx_set found;
-    collect_forward_deps(hidx, result, found);
-}
-
 bool state::del_hypotheses(buffer<hypothesis_idx> const & hs) {
-    hypothesis_idx_set     found;
-    buffer<hypothesis_idx> to_delete;
+    hypothesis_idx_buffer_set to_delete;
     for (hypothesis_idx hidx : hs) {
-        to_delete.push_back(hidx);
-        found.insert(hidx);
-        collect_forward_deps(hidx, to_delete, found);
+        to_delete.insert(hidx);
+        collect_forward_deps(hidx, to_delete);
     }
-    if (!safe_to_delete(to_delete))
+    if (!safe_to_delete(to_delete.as_buffer()))
         return false;
-    del_hypotheses(to_delete, found);
+    del_hypotheses(to_delete.as_buffer(), to_delete.as_set());
     return true;
 }
 
 bool state::del_hypothesis(hypothesis_idx hidx) {
-    hypothesis_idx_set found;
-    buffer<hypothesis_idx> to_delete;
-    to_delete.push_back(hidx);
-    found.insert(hidx);
-    collect_forward_deps(hidx, to_delete, found);
-    if (!safe_to_delete(to_delete))
+    hypothesis_idx_buffer_set to_delete;
+    to_delete.insert(hidx);
+    collect_forward_deps(hidx, to_delete);
+    if (!safe_to_delete(to_delete.as_buffer()))
         return false;
-    del_hypotheses(to_delete, found);
+    del_hypotheses(to_delete.as_buffer(), to_delete.as_set());
     return true;
 }
 
-hypothesis_idx_set state::get_forward_deps(hypothesis_idx hidx) const {
+hypothesis_idx_set state::get_direct_forward_deps(hypothesis_idx hidx) const {
     if (auto r = m_branch.m_forward_deps.find(hidx))
         return *r;
     else

src/library/blast/state.h

@@ -219,9 +219,22 @@ public:
     bool del_hypothesis(hypothesis_idx hidx);
     bool del_hypotheses(buffer<hypothesis_idx> const & hs);
 
+    /** \brief Return the set of hypotheses that (directly) depend on the given one */
+    hypothesis_idx_set get_direct_forward_deps(hypothesis_idx hidx) const;
+    /** \brief Collect in \c result the hypotheses that (directly) depend on \c hidx and satisfy \c pred. */
+    template<typename P>
+    void collect_direct_forward_deps(hypothesis_idx hidx, hypothesis_idx_buffer_set & result, P && pred) {
+        get_direct_forward_deps(hidx).for_each([&](hypothesis_idx d) {
+                if (pred(d)) result.insert(d);
+            });
+    }
+    /** \brief Collect in \c result the hypotheses that (directly) depend on \c hidx and satisfy \c pred. */
+    void collect_direct_forward_deps(hypothesis_idx hidx, hypothesis_idx_buffer_set & result) {
+        return collect_direct_forward_deps(hidx, result, [](hypothesis_idx) { return true; });
+    }
+
     /** \brief Collect all hypothesis in \c result that depend directly or indirectly on hidx */
-    void collect_forward_deps(hypothesis_idx hidx, buffer<hypothesis_idx> & result);
-    void collect_forward_deps(hypothesis_idx hidx, buffer<hypothesis_idx> & result, hypothesis_idx_set & already_found);
+    void collect_forward_deps(hypothesis_idx hidx, hypothesis_idx_buffer_set & result);
 
     /** \brief Return true iff the hypothesis with index \c hidx_user depends on the hypothesis with index
         \c hidx_provider. */
@@ -244,6 +257,7 @@ public:
     void get_sorted_hypotheses(hypothesis_idx_buffer & r) const;
     /** \brief Sort hypotheses in r */
     void sort_hypotheses(hypothesis_idx_buffer & r) const;
+    void sort_hypotheses(hypothesis_idx_buffer_set & r) const;
 
     /** \brief Convert hypotheses indices into hrefs */
     void to_hrefs(hypothesis_idx_buffer const & hidxs, buffer<expr> & r) const;
@@ -261,13 +275,6 @@ public:
     /** \brief Return (active) hypotheses whose head symbol is equal to target or it is the negation of */
     list<hypothesis_idx> get_head_related() const;
 
-    /** \brief Return the set of hypotheses that (directly) depend on the given one */
-    hypothesis_idx_set get_forward_deps(hypothesis_idx hidx) const;
-    template<typename F>
-    void for_each_forward_dep(hypothesis_idx hidx, F && f) const {
-        get_forward_deps(hidx).for_each(f);
-    }
-
     /************************
        Abstracting hypotheses
     *************************/

src/library/blast/subst.cpp

@@ -52,13 +52,11 @@ bool subst_core(hypothesis_idx hidx) {
     lean_verify(is_eq(type, lhs, rhs));
     lean_assert(is_href(rhs));
     try {
-        hypothesis_idx_buffer to_revert;
-        s.for_each_forward_dep(href_index(rhs),
-                               [&](hypothesis_idx d) {
-                                   if (d != hidx) to_revert.push_back(d);
-                               });
-        s.for_each_forward_dep(hidx,
-                               [&](hypothesis_idx d) { to_revert.push_back(d); });
+        hypothesis_idx_buffer_set to_revert;
+        s.collect_direct_forward_deps(href_index(rhs),
+                                      to_revert,
+                                      [&](hypothesis_idx d) { return d != hidx; });
+        s.collect_direct_forward_deps(hidx, to_revert);
         unsigned num = revert_action(to_revert);
         expr target  = s.get_target();
         expr new_target = abstract(target, h->get_self());
@@ -90,7 +88,7 @@ bool subst_action(hypothesis_idx hidx) {
     if (is_href(rhs)) {
         return subst_core(hidx);
     } else if (is_href(lhs)) {
-        if (!s.get_forward_deps(href_index(lhs)).empty()) {
+        if (!s.get_direct_forward_deps(href_index(lhs)).empty()) {
             // TODO(Leo): we don't handle this case yet.
             // Other hypotheses depend on this equality.
             return false;

tests/lean/run/blast6.lean

@@ -0,0 +1,7 @@
+set_option blast.init_depth 10
+
+lemma lemma1 (bv : nat → Type) (n m : nat) (H : n = m) (b1 : bv n) (b2 : bv m) (H2 : eq.rec_on H b1 = b2) : b1 = eq.rec_on (eq.symm H) b2 :=
+by blast
+
+reveal lemma1
+print lemma1