[Tarantool-patches] [PATCH v2] build: disable LUAJIT_ENABLE_PAIRSMM

[Igor Munkin <imun@tarantool.org>]

Since this build flag has been removed as a result of reverting the
tarantool/luajit@d4e985a, its definition in the corresponding Tarantool
cmake file is irrelevant.

Furthermore, considering the breakage faced in #4770 the following tests
are introduced:
* the check whether space __pairs metamethod is set to space.pairs to
  create a Lua Fun iterator that handles __pairs manually underneath.
* the check whether pairs builtin behaviour doesn't change when __pairs
  is set e.g. on space object.

Follow-up #4560
Closes #4770

Signed-off-by: Igor Munkin <imun@tarantool.org>
---

@ChangeLog (need to be added to already released versions):
| __pairs/__ipairs metamethods handling is removed since we faced the
| issues with the backward compatibility between Lua 5.1 and Lua 5.2
| within Tarantool modules as well as other third party code (gh-4770).

Issue: https://github.com/tarantool/tarantool/issues/4770
Branch: https://github.com/tarantool/tarantool/tree/imun/gh-4770-broken-pairs

v1: https://lists.tarantool.org/pipermail/tarantool-patches/2020-February/014375.html

Changes in v2:
* moved test to a separate file

 cmake/luajit.cmake                            |  1 -
 ...4770-broken-pairs-for-space-objects.result | 52 +++++++++++++++++++
 ...70-broken-pairs-for-space-objects.test.lua | 18 +++++++
 3 files changed, 70 insertions(+), 1 deletion(-)
 create mode 100644 test/box/gh-4770-broken-pairs-for-space-objects.result
 create mode 100644 test/box/gh-4770-broken-pairs-for-space-objects.test.lua

diff --git a/cmake/luajit.cmake b/cmake/luajit.cmake
index 072db8269..10df633d5 100644
--- a/cmake/luajit.cmake
+++ b/cmake/luajit.cmake
@@ -217,7 +217,6 @@ macro(luajit_build)
         add_definitions(-DLUAJIT_USE_ASAN=1)
         set (luajit_ldflags ${luajit_ldflags} -fsanitize=address)
     endif()
-    add_definitions(-DLUAJIT_ENABLE_PAIRSMM=1)
     add_definitions(-DLUAJIT_SMART_STRINGS=1)
     # Add all COMPILE_DEFINITIONS to xcflags
     get_property(defs DIRECTORY PROPERTY COMPILE_DEFINITIONS)
diff --git a/test/box/gh-4770-broken-pairs-for-space-objects.result b/test/box/gh-4770-broken-pairs-for-space-objects.result
new file mode 100644
index 000000000..61618453e
--- /dev/null
+++ b/test/box/gh-4770-broken-pairs-for-space-objects.result
@@ -0,0 +1,52 @@
+-- test-run result file version 2
+env = require('test_run')
+ | ---
+ | ...
+test_run = env.new()
+ | ---
+ | ...
+test_run:cmd("push filter 'table: .*' to 'table: <address>'")
+ | ---
+ | - true
+ | ...
+
+--
+-- gh-4770: Iteration through space with Lua builtin pairs routine
+--
+box.cfg{}
+ | ---
+ | ...
+s = box.schema.create_space('test')
+ | ---
+ | ...
+-- Check whether __pairs is set for the space object, since Lua Fun
+-- handles it manually underneath.
+getmetatable(s).__pairs == s.pairs
+ | ---
+ | - true
+ | ...
+-- Check whether pairs builtin behaviour doesn't change when the
+-- __pairs is set.
+keys = {}
+ | ---
+ | ...
+for k, v in pairs(s) do keys[k] = true end
+ | ---
+ | ...
+keys
+ | ---
+ | - engine: true
+ |   before_replace: true
+ |   field_count: true
+ |   id: true
+ |   on_replace: true
+ |   temporary: true
+ |   index: true
+ |   is_local: true
+ |   enabled: true
+ |   name: true
+ |   ck_constraint: true
+ | ...
+s:drop()
+ | ---
+ | ...
diff --git a/test/box/gh-4770-broken-pairs-for-space-objects.test.lua b/test/box/gh-4770-broken-pairs-for-space-objects.test.lua
new file mode 100644
index 000000000..15024a803
--- /dev/null
+++ b/test/box/gh-4770-broken-pairs-for-space-objects.test.lua
@@ -0,0 +1,18 @@
+env = require('test_run')
+test_run = env.new()
+test_run:cmd("push filter 'table: .*' to 'table: <address>'")
+
+--
+-- gh-4770: Iteration through space with Lua builtin pairs routine
+--
+box.cfg{}
+s = box.schema.create_space('test')
+-- Check whether __pairs is set for the space object, since Lua Fun
+-- handles it manually underneath.
+getmetatable(s).__pairs == s.pairs
+-- Check whether pairs builtin behaviour doesn't change when the
+-- __pairs is set.
+keys = {}
+for k, v in pairs(s) do keys[k] = true end
+keys
+s:drop()
-- 
2.25.0