diff --git a/src/library/tactic/induction_tactic.cpp b/src/library/tactic/induction_tactic.cpp index d444fe0f2..fa997d429 100644 --- a/src/library/tactic/induction_tactic.cpp +++ b/src/library/tactic/induction_tactic.cpp @@ -228,7 +228,8 @@ class induction_tac { } } buffer indices; - for (unsigned pos : rec_info.get_indices_pos()) { + list const & idx_pos = rec_info.get_indices_pos(); + for (unsigned pos : idx_pos) { if (pos >= h_type_args.size()) { throw tactic_exception("invalid 'induction' tactic, major premise type is ill-formed"); } @@ -243,6 +244,14 @@ class induction_tac { << pos+1 << " of major premise '" << h << "' type is an index, " << "but it occurs more than once"); } + if (i > pos && // occurs after idx + std::find(idx_pos.begin(), idx_pos.end(), i) != idx_pos.end() && // it is also an index + is_local(h_type_args[i]) && // if it is not an index, it will fail anyway. + depends_on(mlocal_type(idx), h_type_args[i])) { + throw tactic_exception(sstream() << "invalid 'induction' tactic, argument #" + << pos+1 << " of major premise '" << h << "' type is an index, " + << "but its type depends on the index at position #" << i+1); + } } indices.push_back(idx); } diff --git a/tests/lean/690.hlean b/tests/lean/690.hlean new file mode 100644 index 000000000..db3357b8a --- /dev/null +++ b/tests/lean/690.hlean @@ -0,0 +1,12 @@ +-- HoTT +import types.sigma +open sigma sigma.ops eq +definition dpair_sigma_eq {A : Type} {B : A → Type} {u v : Σa, B a} (p : u.1 = v.1) (q : u.2 =[p] v.2) + : ⟨(sigma_eq p q)..1, (sigma_eq p q)..2⟩ = ⟨p, q⟩ := +begin + induction u with u₁ u₂, + induction v with v₁ v₂, + esimp at q, + induction q, -- Should fail here since index p depends one index v₂ + reflexivity +end diff --git a/tests/lean/690.hlean.expected.out b/tests/lean/690.hlean.expected.out new file mode 100644 index 000000000..4d05275fd --- /dev/null +++ b/tests/lean/690.hlean.expected.out @@ -0,0 +1,21 @@ +690.hlean:10:2: error:invalid 'induction' tactic, invalid 'induction' tactic, argument #6 of major premise 'q' type is an index, but its type depends on the index at position #7 +proof state: +A : Type, +B : A → Type, +u₁ : A, +u₂ : B u₁, +v₁ : A, +v₂ : B v₁, +p : ⟨u₁, u₂⟩.1 = ⟨v₁, v₂⟩.1, +q : u₂ =[ p ] v₂ +⊢ ⟨(sigma_eq p q)..1, (sigma_eq p q)..2⟩ = ⟨p, q⟩ +690.hlean:12:0: error: don't know how to synthesize placeholder +A : Type, +B : A → Type, +u v : Σ (a : A), B a, +p : u.1 = v.1, +q : u.2 =[ p ] v.2 +⊢ ⟨(sigma_eq p q)..1, (sigma_eq p q)..2⟩ = ⟨p, q⟩ +690.hlean:12:0: error: failed to add declaration 'dpair_sigma_eq' to environment, value has metavariables +remark: set 'formatter.hide_full_terms' to false to see the complete term + ?M_1