detect LuaJIT dynamically

This reduces the complexity of the interaction between
build-time configuration, run-time auto-detection, and overrides via
CLI flags. The LuaJIT version is now always auto-detected at run-time
based on the Lua interpreter currently configured, based on the values
of configuration options `variables.LUA_BINDIR` and `lua_interpreter`.

10 files changed, 103 insertions, 67 deletions

diff --git a/src/luarocks/cmd/help.lua b/src/luarocks/cmd/help.lua
index a508953a..b3d937e1 100644
--- a/src/luarocks/cmd/help.lua
+++ b/src/luarocks/cmd/help.lua
@@ -85,8 +85,9 @@ function help.command(description, commands, command)
       end
       print_section("CONFIGURATION")
       util.printout("\tLua version: " .. cfg.lua_version)
-      if cfg.luajit_version then
-         util.printout("\tLuaJIT version: " .. cfg.luajit_version)
+      local ljv = util.get_luajit_version()
+      if ljv then
+         util.printout("\tLuaJIT version: " .. ljv)
       end
       util.printout()
       util.printout("\tConfiguration files:")
diff --git a/src/luarocks/cmd/init.lua b/src/luarocks/cmd/init.lua
index 0da9c88f..88de283b 100644
--- a/src/luarocks/cmd/init.lua
+++ b/src/luarocks/cmd/init.lua
@@ -110,7 +110,6 @@ function init.command(flags, name, version)
    if config_tbl then
       local globals = {
          "lua_interpreter",
-         "luajit_version",
       }
       for _, v in ipairs(globals) do
          if cfg[v] then
diff --git a/src/luarocks/cmd/show.lua b/src/luarocks/cmd/show.lua
index bb0fdfd7..37c2c55e 100644
--- a/src/luarocks/cmd/show.lua
+++ b/src/luarocks/cmd/show.lua
@@ -116,8 +116,9 @@ end
 
 local function installed_rock_label(dep, tree)
    local installed, version
-   if cfg.rocks_provided[dep.name] then
-      installed, version = true, cfg.rocks_provided[dep.name]
+   local rocks_provided = util.get_rocks_provided()
+   if rocks_provided[dep.name] then
+      installed, version = true, rocks_provided[dep.name]
    else
       installed, version = search.pick_installed_rock(dep, tree)
    end
diff --git a/src/luarocks/core/cfg.lua b/src/luarocks/core/cfg.lua
index a1ebe4e4..c50e0a44 100644
--- a/src/luarocks/core/cfg.lua
+++ b/src/luarocks/core/cfg.lua
@@ -481,43 +481,18 @@ local function make_defaults(lua_version, target_cpu, platforms, home)
    return defaults
 end
 
-local function make_rocks_provided(lua_version, luajit_version)
-   local rocks_provided = {}
-   local rocks_provided_3_0 = {}
-
-   rocks_provided["lua"] = lua_version.."-1"
-
-   if lua_version == "5.2" or lua_version == "5.3" then
-      rocks_provided["bit32"] = lua_version.."-1"
-   end
-
-   if lua_version == "5.3" or lua_version == "5.4" then
-      rocks_provided["utf8"] = lua_version.."-1"
-   end
-
-   if luajit_version then
-      rocks_provided["luabitop"] = luajit_version.."-1"
-      rocks_provided_3_0["luajit"] = luajit_version.."-1"
-   end
-
-   return rocks_provided, rocks_provided_3_0
-end
-
 local function use_defaults(cfg, defaults)
 
-   -- Populate some arrays with values from their 'defaults' counterparts
+   -- Populate variables with values from their 'defaults' counterparts
    -- if they were not already set by user.
-   for _, entry in ipairs({"variables", "rocks_provided"}) do
-      if not cfg[entry] then
-         cfg[entry] = {}
-      end
-      for k,v in pairs(defaults[entry]) do
-         if not cfg[entry][k] then
-            cfg[entry][k] = v
-         end
+   if not cfg.variables then
+      cfg.variables = {}
+   end
+   for k,v in pairs(defaults.variables) do
+      if not cfg.variables[k] then
+         cfg.variables[k] = v
       end
    end
-   util.deep_merge_under(defaults.rocks_provided_3_0, cfg.rocks_provided)
 
    util.deep_merge_under(cfg, defaults)
 
@@ -537,7 +512,6 @@ local cfg = {}
 -- @param detected table containing information detected about the 
 -- environment. All fields below are optional:
 -- * lua_version (in x.y format, e.g. "5.3")
--- * luajit_version (complete, e.g. "2.1.0-beta3")
 -- * lua_bindir (e.g. "/usr/local/bin")
 -- * lua_incdir (e.g. "/usr/local/include/lua5.3/")
 -- * lua_libdir(e.g. "/usr/local/lib")
@@ -556,7 +530,6 @@ function cfg.init(detected, warning)
    end
 
    local lua_version = detected.lua_version or hardcoded.LUA_VERSION or _VERSION:sub(5)
-   local luajit_version = detected.luajit_version or hardcoded.LUAJIT_VERSION or (jit and jit.version:sub(8))
    local lua_interpreter = detected.lua_interpreter or hardcoded.LUA_INTERPRETER or (arg and arg[-1] and arg[-1]:gsub(".*[\\/]", "")) or (is_windows and "lua.exe" or "lua")
    local lua_bindir = detected.lua_bindir or hardcoded.LUA_BINDIR or (arg and arg[-1] and arg[-1]:gsub("[\\/][^\\/]+$", ""))
    local lua_incdir = detected.lua_incdir or hardcoded.LUA_INCDIR
@@ -579,7 +552,6 @@ function cfg.init(detected, warning)
    cfg.major_version = major_version
 
    cfg.lua_version = lua_version
-   cfg.luajit_version = luajit_version
    cfg.lua_interpreter = lua_interpreter
 
    cfg.variables = {
@@ -698,7 +670,6 @@ function cfg.init(detected, warning)
    -- Settings detected or given via the CLI (i.e. --lua-dir) take precedence over config files:
    cfg.project_dir = project_dir
    cfg.lua_version = detected.lua_version or cfg.lua_version
-   cfg.luajit_version = detected.luajit_version or cfg.luajit_version
    cfg.lua_interpreter = detected.lua_interpreter or cfg.lua_interpreter
    cfg.variables.LUA_BINDIR = detected.lua_bindir or cfg.variables.LUA_BINDIR or lua_bindir
    cfg.variables.LUA_INCDIR = detected.lua_incdir or cfg.variables.LUA_INCDIR or lua_incdir
@@ -727,7 +698,6 @@ function cfg.init(detected, warning)
       defaults.fs_use_modules = true
    end
 
-   defaults.rocks_provided, defaults.rocks_provided_3_0 = make_rocks_provided(lua_version, luajit_version)
    use_defaults(cfg, defaults)
 
    cfg.variables.LUA = cfg.variables.LUA or (cfg.variables.LUA_BINDIR and (cfg.variables.LUA_BINDIR .. "/" .. cfg.lua_interpreter):gsub("//", "/"))
@@ -752,6 +722,8 @@ function cfg.init(detected, warning)
                     and home_config_file
                     or sys_config_file),
    }
+   
+   cfg.cache = {}
 
    ----------------------------------------
    -- Attributes of cfg are set.
diff --git a/src/luarocks/core/util.lua b/src/luarocks/core/util.lua
index 6a306026..d8f75d76 100644
--- a/src/luarocks/core/util.lua
+++ b/src/luarocks/core/util.lua
@@ -120,13 +120,14 @@ function util.show_table(t, tname, top_indent)
    return cart .. autoref
 end
 
---- Merges contents of src on top of dst's contents.
+--- Merges contents of src on top of dst's contents
+-- (i.e. if an key from src already exists in dst, replace it).
 -- @param dst Destination table, which will receive src's contents.
 -- @param src Table which provides new contents to dst.
 function util.deep_merge(dst, src)
    for k, v in pairs(src) do
       if type(v) == "table" then
-         if not dst[k] then
+         if dst[k] == nil then
             dst[k] = {}
          end
          if type(dst[k]) == "table" then
@@ -140,13 +141,14 @@ function util.deep_merge(dst, src)
    end
 end
 
---- Merges contents of src below those of dst's contents.
+--- Merges contents of src below those of dst's contents
+-- (i.e. if an key from src already exists in dst, do not replace it).
 -- @param dst Destination table, which will receive src's contents.
 -- @param src Table which provides new contents to dst.
 function util.deep_merge_under(dst, src)
    for k, v in pairs(src) do
       if type(v) == "table" then
-         if not dst[k] then
+         if dst[k] == nil then
             dst[k] = {}
          end
          if type(dst[k]) == "table" then
diff --git a/src/luarocks/deps.lua b/src/luarocks/deps.lua
index 6eb19aba..874787da 100644
--- a/src/luarocks/deps.lua
+++ b/src/luarocks/deps.lua
@@ -497,7 +497,7 @@ function deps.scan_deps(results, manifest, name, version, deps_mode)
       rocks_provided = rockspec.rocks_provided
       mdn[version] = dependencies
    else
-      rocks_provided = setmetatable({}, { __index = cfg.rocks_provided_3_0 })
+      rocks_provided = util.get_rocks_provided()
    end
    local matched = deps.match_deps(dependencies, rocks_provided, nil, deps_mode)
    results[name] = version
@@ -533,8 +533,9 @@ end
 
 function deps.check_lua(vars)
    local incdir_found = true
+   local ljv = util.get_luajit_version()
    if (not vars.LUA_INCDIR) and vars.LUA_DIR then
-      vars.LUA_INCDIR = find_lua_incdir(vars.LUA_DIR, cfg.lua_version, cfg.luajit_version)
+      vars.LUA_INCDIR = find_lua_incdir(vars.LUA_DIR, cfg.lua_version, ljv)
       incdir_found = (vars.LUA_INCDIR ~= nil)
    end
    local shortv = cfg.lua_version:gsub("%.", "")
@@ -545,7 +546,7 @@ function deps.check_lua(vars)
       "lua-" .. shortv,
       "lua",
    }
-   if cfg.luajit_version then
+   if ljv then
       table.insert(libnames, 1, "luajit-" .. cfg.lua_version)
    end
    local cache = {}
diff --git a/src/luarocks/manif/writer.lua b/src/luarocks/manif/writer.lua
index 6f70338b..23ba2532 100644
--- a/src/luarocks/manif/writer.lua
+++ b/src/luarocks/manif/writer.lua
@@ -453,7 +453,7 @@ function writer.check_dependencies(repo, deps_mode)
          for _, entry in ipairs(version_entries) do
             if entry.arch == "installed" then
                if manifest.dependencies[name] and manifest.dependencies[name][version] then
-                  deps.report_missing_dependencies(name, version, manifest.dependencies[name][version], deps_mode, cfg.rocks_provided_3_0)
+                  deps.report_missing_dependencies(name, version, manifest.dependencies[name][version], deps_mode, util.get_rocks_provided())
                end
             end
          end
diff --git a/src/luarocks/rockspecs.lua b/src/luarocks/rockspecs.lua
index fe4a6d74..f1bb6d6a 100644
--- a/src/luarocks/rockspecs.lua
+++ b/src/luarocks/rockspecs.lua
@@ -5,7 +5,7 @@ local dir = require("luarocks.dir")
 local path = require("luarocks.path")
 local queries = require("luarocks.queries")
 local type_rockspec = require("luarocks.type.rockspec")
-local util = require("luarocks.core.util")
+local util = require("luarocks.util")
 local vers = require("luarocks.core.vers")
 
 local rockspec_mt = {}
@@ -142,9 +142,7 @@ function rockspecs.from_persisted_table(filename, rockspec, globals, quick)
                                 or  ".") )
                       or base
 
-   rockspec.rocks_provided = (rockspec:format_is_at_least("3.0")
-                              and cfg.rocks_provided_3_0
-                              or  cfg.rocks_provided)
+   rockspec.rocks_provided = util.get_rocks_provided(rockspec)
 
    for _, key in ipairs({"dependencies", "build_dependencies", "test_dependencies"}) do
       local ok, err = convert_dependencies(rockspec, key)
diff --git a/src/luarocks/search.lua b/src/luarocks/search.lua
index a11d959c..e5ee9b47 100644
--- a/src/luarocks/search.lua
+++ b/src/luarocks/search.lua
@@ -164,9 +164,9 @@ function search.search_repos(query, lua_version)
          end
       end
    end
-   -- search through rocks in cfg.rocks_provided
+   -- search through rocks in rocks_provided
    local provided_repo = "provided by VM or rocks_provided"
-   for name, version in pairs(cfg.rocks_provided) do
+   for name, version in pairs(util.get_rocks_provided()) do
       local result = results.new(name, version, provided_repo, "installed")
       store_if_match(result_tree, result, query)
    end
@@ -242,9 +242,11 @@ end
 function search.find_suitable_rock(query, cli)
    assert(query:type() == "query")
 
-   if cfg.rocks_provided[query.name] ~= nil then
-      -- Do not install versions listed in cfg.rocks_provided.
-      return nil, "Rock "..query.name.." "..cfg.rocks_provided[query.name]..
+   local rocks_provided = util.get_rocks_provided()
+   
+   if rocks_provided[query.name] ~= nil then
+      -- Do not install versions listed in rocks_provided.
+      return nil, "Rock "..query.name.." "..rocks_provided[query.name]..
          " is already provided by VM or via 'rocks_provided' in the config file."
    end
    
diff --git a/src/luarocks/util.lua b/src/luarocks/util.lua
index 57cefc61..6caba8cd 100644
--- a/src/luarocks/util.lua
+++ b/src/luarocks/util.lua
@@ -588,14 +588,25 @@ do
       if luaver and luaver ~= lv then
          return nil
       end
+      return lv
+   end
+
+   function util.get_luajit_version()
+      local cfg = require("luarocks.core.cfg")
+      if cfg.cache.luajit_version_checked then
+         return cfg.cache.luajit_version 
+      end
+      cfg.cache.luajit_version_checked = true
+
       local ljv
-      if lv == "5.1" then
-         ljv = util.popen_read(Q(lua_exe) .. ' -e "io.write(tostring(jit and jit.version:sub(8)))"')
+      if cfg.lua_version == "5.1" then
+         ljv = util.popen_read(Q(cfg.variables["LUA_BINDIR"] .. "/" .. cfg.lua_interpreter) .. ' -e "io.write(tostring(jit and jit.version:sub(8)))"')
          if ljv == "nil" then
             ljv = nil
          end
       end
-      return lv, ljv
+      cfg.cache.luajit_version = ljv
+      return ljv
    end
 
    local find_lua_bindir
@@ -636,9 +647,9 @@ do
                local lua_exe = d .. "/" .. name
                local is_wrapper, err = util.lua_is_wrapper(lua_exe)
                if is_wrapper == false then
-                  local lv, ljv = util.check_lua_version(lua_exe, luaver)
+                  local lv = util.check_lua_version(lua_exe, luaver)
                   if lv then
-                     return name, d, lv, ljv
+                     return name, d, lv
                   end
                elseif is_wrapper == true or err == nil then
                   table.insert(tried, lua_exe)
@@ -656,15 +667,14 @@ do
    end
 
    function util.find_lua(prefix, luaver)
-      local lua_interpreter, bindir, luajitver
-      lua_interpreter, bindir, luaver, luajitver = find_lua_bindir(prefix, luaver)
+      local lua_interpreter, bindir
+      lua_interpreter, bindir, luaver = find_lua_bindir(prefix, luaver)
       if not lua_interpreter then
          return nil, bindir
       end
 
       return {
          lua_version = luaver,
-         luajit_version = luajitver,
          lua_interpreter = lua_interpreter,
          lua_dir = prefix,
          lua_bindir = bindir,
@@ -714,5 +724,55 @@ function util.opts_table(type_name, valid_opts)
    end
 end
 
+--- Return a table of modules that are already provided by the VM, which
+-- can be specified as dependencies without having to install an actual rock.
+-- @param rockspec (optional) a rockspec table, so that rockspec format
+-- version compatibility can be checked. If not given, maximum compatibility
+-- is assumed.
+-- @return a table with rock names as keys and versions and values,
+-- specifying modules that are already provided by the VM (including
+-- "lua" for the Lua version and, for format 3.0+, "luajit" if detected).
+function util.get_rocks_provided(rockspec)
+   local cfg = require("luarocks.core.cfg")
+   
+   if not rockspec and cfg.cache.rocks_provided then
+      return cfg.cache.rocks_provided
+   end
+
+   local rocks_provided = {}
+
+   local lv = cfg.lua_version
+
+   rocks_provided["lua"] = lv.."-1"
+
+   if lv == "5.2" or lv == "5.3" then
+      rocks_provided["bit32"] = lv.."-1"
+   end
+
+   if lv == "5.3" or lv == "5.4" then
+      rocks_provided["utf8"] = lv.."-1"
+   end
+
+   if lv == "5.1" then
+      local ljv = util.get_luajit_version()
+      if ljv then
+         rocks_provided["luabitop"] = ljv.."-1"
+         if (not rockspec) or rockspec:format_is_at_least("3.0") then
+            rocks_provided["luajit"] = ljv.."-1"
+         end
+      end
+   end
+
+   if cfg.rocks_provided then
+      util.deep_merge_under(rocks_provided, cfg.rocks_provided)
+   end
+
+   if not rockspec then
+      cfg.cache.rocks_provided = rocks_provided
+   end
+
+   return rocks_provided
+end
+
 return util