merge(3p/immer): Subtree merge at 'ad3e3556d' as 'third_party/immer'

Change-Id: I9636a41ad44b4218293833fd3e9456d9b07c731b

third_party/immer/extra/fuzzer/flex-vector-gc.cpp

@@ -0,0 +1,162 @@
+//
+// immer: immutable data structures for C++
+// Copyright (C) 2016, 2017, 2018 Juan Pedro Bolivar Puente
+//
+// This software is distributed under the Boost Software License, Version 1.0.
+// See accompanying file LICENSE or copy at http://boost.org/LICENSE_1_0.txt
+//
+
+#include "fuzzer_input.hpp"
+
+#include <immer/flex_vector.hpp>
+#include <immer/flex_vector_transient.hpp>
+#include <immer/heap/gc_heap.hpp>
+#include <immer/refcount/no_refcount_policy.hpp>
+
+#include <array>
+
+using gc_memory = immer::memory_policy<immer::heap_policy<immer::gc_heap>,
+                                       immer::no_refcount_policy,
+                                       immer::gc_transience_policy,
+                                       false>;
+
+extern "C" int LLVMFuzzerTestOneInput(const std::uint8_t* data,
+                                      std::size_t size)
+{
+    constexpr auto var_count = 4;
+    constexpr auto bits      = 2;
+
+    using vector_t    = immer::flex_vector<int, gc_memory, bits, bits>;
+    using transient_t = typename vector_t::transient_type;
+    using size_t      = std::uint8_t;
+
+    auto vs = std::array<vector_t, var_count>{};
+    auto ts = std::array<transient_t, var_count>{};
+
+    auto is_valid_var = [&](auto idx) { return idx >= 0 && idx < var_count; };
+    auto is_valid_var_neq = [](auto other) {
+        return [=](auto idx) {
+            return idx >= 0 && idx < var_count && idx != other;
+        };
+    };
+    auto is_valid_index = [](auto& v) {
+        return [&](auto idx) { return idx >= 0 && idx < v.size(); };
+    };
+    auto is_valid_size = [](auto& v) {
+        return [&](auto idx) { return idx >= 0 && idx <= v.size(); };
+    };
+    auto can_concat = [](auto&& v1, auto&& v2) {
+        using size_type = decltype(v1.size());
+        auto max        = std::numeric_limits<size_type>::max() >> (bits * 4);
+        return v1.size() < max && v2.size() < max;
+    };
+
+    return fuzzer_input{data, size}.run([&](auto& in) {
+        enum ops
+        {
+            op_transient,
+            op_persistent,
+            op_push_back,
+            op_update,
+            op_take,
+            op_drop,
+            op_concat,
+            op_push_back_mut,
+            op_update_mut,
+            op_take_mut,
+            op_drop_mut,
+            op_prepend_mut,
+            op_prepend_mut_move,
+            op_append_mut,
+            op_append_mut_move,
+        };
+        auto dst = read<char>(in, is_valid_var);
+        switch (read<char>(in)) {
+        case op_transient: {
+            auto src = read<char>(in, is_valid_var);
+            ts[dst]  = vs[src].transient();
+            break;
+        }
+        case op_persistent: {
+            auto src = read<char>(in, is_valid_var);
+            vs[dst]  = ts[src].persistent();
+            break;
+        }
+        case op_push_back: {
+            auto src = read<char>(in, is_valid_var);
+            vs[dst]  = vs[src].push_back(42);
+            break;
+        }
+        case op_update: {
+            auto src = read<char>(in, is_valid_var);
+            auto idx = read<size_t>(in, is_valid_index(vs[src]));
+            vs[dst]  = vs[src].update(idx, [](auto x) { return x + 1; });
+            break;
+        }
+        case op_take: {
+            auto src = read<char>(in, is_valid_var);
+            auto idx = read<size_t>(in, is_valid_size(vs[src]));
+            vs[dst]  = vs[src].take(idx);
+            break;
+        }
+        case op_drop: {
+            auto src = read<char>(in, is_valid_var);
+            auto idx = read<size_t>(in, is_valid_size(vs[src]));
+            vs[dst]  = vs[src].drop(idx);
+            break;
+        }
+        case op_concat: {
+            auto src  = read<char>(in, is_valid_var);
+            auto src2 = read<char>(in, is_valid_var);
+            if (can_concat(vs[src], vs[src2]))
+                vs[dst] = vs[src] + vs[src2];
+            break;
+        }
+        case op_push_back_mut: {
+            ts[dst].push_back(13);
+            break;
+        }
+        case op_update_mut: {
+            auto idx = read<size_t>(in, is_valid_index(ts[dst]));
+            ts[dst].update(idx, [](auto x) { return x + 1; });
+            break;
+        }
+        case op_take_mut: {
+            auto idx = read<size_t>(in, is_valid_size(ts[dst]));
+            ts[dst].take(idx);
+            break;
+        }
+        case op_prepend_mut: {
+            auto src = read<char>(in, is_valid_var_neq(dst));
+            if (can_concat(ts[dst], ts[src]))
+                ts[dst].prepend(ts[src]);
+            break;
+        }
+        case op_prepend_mut_move: {
+            auto src = read<char>(in, is_valid_var_neq(dst));
+            if (can_concat(ts[dst], ts[src])) {
+                ts[dst].prepend(std::move(ts[src]));
+                ts[src] = {};
+            }
+            break;
+        }
+        case op_append_mut: {
+            auto src = read<char>(in, is_valid_var_neq(dst));
+            if (can_concat(ts[dst], ts[src]))
+                ts[dst].append(ts[src]);
+            break;
+        }
+        case op_append_mut_move: {
+            auto src = read<char>(in, is_valid_var_neq(dst));
+            if (can_concat(ts[dst], ts[src])) {
+                ts[dst].append(std::move(ts[src]));
+                ts[src] = {};
+            }
+            break;
+        }
+        default:
+            break;
+        };
+        return true;
+    });
+}