improve and simplify Lua interpreter search

* do not proceed with commands if interpreter is not found
* begin retiring LUA_DIR and LUA_BINDIR, and promote LUA as
  the main way to setup the interpreter location (from which
  we derive the rest)

5 files changed, 49 insertions, 40 deletions

diff --git a/src/luarocks/cmd.lua b/src/luarocks/cmd.lua
index 3067f4ce..30293d6b 100644
--- a/src/luarocks/cmd.lua
+++ b/src/luarocks/cmd.lua
@@ -340,14 +340,18 @@ Variables:
 
 ]]
 
-local function get_status(status)
-   return status and "ok" or "not found"
+local lua_example = package.config:sub(1, 1) == "\\"
+                    and "<d:\\path\\lua.exe>"
+                    or  "</path/lua>"
+
+local function show_status(file, status)
+   return (file and file .. " " or "") .. (status and "(ok)" or "(not found)")
 end
 
-local function use_to_fix_location(key)
+local function use_to_fix_location(key, what)
    local buf =  "                   ****************************************\n"
    buf = buf .. "                   Use the command\n\n"
-   buf = buf .. "                      luarocks config " .. key .. " <dir>\n\n"
+   buf = buf .. "                      luarocks config " .. key .. " " .. (what or "<dir>") .. "\n\n"
    buf = buf .. "                   to fix the location\n"
    buf = buf .. "                   ****************************************\n"
    return buf
@@ -358,8 +362,6 @@ local function get_config_text(cfg)  -- luacheck: ignore 431
 
    local libdir_ok = deps.check_lua_libdir(cfg.variables)
    local incdir_ok = deps.check_lua_incdir(cfg.variables)
-   local bindir_ok = cfg.variables.LUA_BINDIR and fs.exists(cfg.variables.LUA_BINDIR)
-   local luadir_ok = cfg.variables.LUA_DIR and fs.exists(cfg.variables.LUA_DIR)
    local lua_ok = cfg.variables.LUA and fs.exists(cfg.variables.LUA)
 
    local buf = "Configuration:\n"
@@ -368,31 +370,29 @@ local function get_config_text(cfg)  -- luacheck: ignore 431
    if cfg.luajit_version then
       buf = buf.."      LuaJIT     : "..cfg.luajit_version.."\n"
    end
-   buf = buf.."      Interpreter: "..(cfg.variables.LUA or "").." ("..get_status(lua_ok)..")\n"
-   buf = buf.."      LUA_DIR    : "..(cfg.variables.LUA_DIR or "").." ("..get_status(luadir_ok)..")\n"
+   buf = buf.."      LUA        : "..show_status(cfg.variables.LUA, lua_ok).."\n"
    if not lua_ok then
-      buf = buf .. use_to_fix_location("lua_dir")
+      buf = buf .. use_to_fix_location("variables.LUA", lua_example)
    end
-   buf = buf.."      LUA_BINDIR : "..(cfg.variables.LUA_BINDIR or "").." ("..get_status(bindir_ok)..")\n"
-   buf = buf.."      LUA_INCDIR : "..(cfg.variables.LUA_INCDIR or "").." ("..get_status(incdir_ok)..")\n"
+   buf = buf.."      LUA_INCDIR : "..show_status(cfg.variables.LUA_INCDIR, incdir_ok).."\n"
    if lua_ok and not incdir_ok then
       buf = buf .. use_to_fix_location("variables.LUA_INCDIR")
    end
-   buf = buf.."      LUA_LIBDIR : "..(cfg.variables.LUA_LIBDIR or "").." ("..get_status(libdir_ok)..")\n"
+   buf = buf.."      LUA_LIBDIR : "..show_status(cfg.variables.LUA_LIBDIR, libdir_ok).."\n"
    if lua_ok and not libdir_ok then
       buf = buf .. use_to_fix_location("variables.LUA_LIBDIR")
    end
 
    buf = buf.."\n   Configuration files:\n"
    local conf = cfg.config_files
-   buf = buf.."      System  : "..fs.absolute_name(conf.system.file).." ("..get_status(conf.system.found)..")\n"
+   buf = buf.."      System  : "..show_status(fs.absolute_name(conf.system.file), conf.system.found).."\n"
    if conf.user.file then
-      buf = buf.."      User    : "..fs.absolute_name(conf.user.file).." ("..get_status(conf.user.found)..")\n"
+      buf = buf.."      User    : "..show_status(fs.absolute_name(conf.user.file), conf.user.found).."\n"
    else
       buf = buf.."      User    : disabled in this LuaRocks installation.\n"
    end
    if conf.project then
-      buf = buf.."      Project : "..fs.absolute_name(conf.project.file).." ("..get_status(conf.project.found)..")\n"
+      buf = buf.."      Project : "..show_status(fs.absolute_name(conf.project.file), conf.project.found).."\n"
    end
    buf = buf.."\n   Rocks trees in use: \n"
    for _, tree in ipairs(cfg.rocks_trees) do
@@ -638,33 +638,35 @@ function cmd.run_command(description, commands, external_namespace, ...)
             cfg.variables.LUA_INCDIR = nil
             cfg.variables.LUA_LIBDIR = nil
          end
+      else
+         cfg.variables.LUA = nil
+         cfg.variables.LUA_DIR = nil
+         cfg.variables.LUA_BINDIR = nil
+         cfg.variables.LUA_INCDIR = nil
+         cfg.variables.LUA_LIBDIR = nil
       end
    end
 
    if lua_found then
       assert(cfg.variables.LUA)
    else
-      if args.command ~= "config" and args.command ~= "help" then
-         util.warning(tried ..
-                      "\nModules may not install with the correct configurations. " ..
-                      "You may want to configure the path prefix to your build " ..
-                      "of Lua " .. cfg.lua_version .. " using\n\n" ..
-                      "   luarocks config --local lua_dir <your-lua-prefix>\n")
-      end
-
       -- Fallback producing _some_ Lua configuration based on the running interpreter.
       -- Most likely won't produce correct results when running from the standalone binary,
       -- so eventually we need to drop this and outright fail if Lua is not found
       -- or explictly configured
       if not cfg.variables.LUA then
          local first_arg = get_first_arg()
-         cfg.variables.LUA_DIR = dir.dir_name(fs.absolute_name(first_arg))
-         cfg.variables.LUA_BINDIR = cfg.variables.LUA_DIR
-         local exe = fs.base_name(first_arg)
+         local bin_dir = dir.dir_name(fs.absolute_name(first_arg))
+         local exe = dir.base_name(first_arg)
          exe = exe:match("rocks") and ("lua" .. (cfg.arch:match("win") and ".exe" or "")) or exe
-         cfg.variables.LUA = dir.path(cfg.variables.LUA_BINDIR, exe)
-         cfg.variables.LUA_INCDIR = nil
-         cfg.variables.LUA_LIBDIR = nil
+         local full_path = dir.path(bin_dir, exe)
+         if util.check_lua_version(full_path, cfg.lua_version) then
+            cfg.variables.LUA = dir.path(bin_dir, exe)
+            cfg.variables.LUA_DIR = bin_dir:gsub("[/\\]bin[/\\]?$", "")
+            cfg.variables.LUA_BINDIR = bin_dir
+            cfg.variables.LUA_INCDIR = nil
+            cfg.variables.LUA_LIBDIR = nil
+         end
       end
    end
 
@@ -718,10 +720,16 @@ function cmd.run_command(description, commands, external_namespace, ...)
       os.exit(cmd.errorcodes.OK)
    end
 
-   if not cfg.variables["LUA_BINDIR"] then
-      return nil, "LUA_BINDIR not configured.\n" ..
-         "Please configure the location of the Lua interpreter with:\n" ..
-         "   luarocks config variables.LUA_BINDIR <path>"
+   if not cfg.variables["LUA"] and args.command ~= "config" and args.command ~= "help" then
+      local flag = (not cfg.project_tree)
+                   and "--local "
+                   or ""
+      if args.lua_version then
+         flag = "--lua-version=" .. args.lua_version .. " " .. flag
+      end
+      die((tried or "Lua interpreter not found.") ..
+         "\nPlease set your Lua interpreter with:\n\n" ..
+         "   luarocks " .. flag.. "config variables.LUA " .. lua_example .. "\n")
    end
 
    local cmd_mod = cmd_modules[args.command]
diff --git a/src/luarocks/cmd/init.lua b/src/luarocks/cmd/init.lua
index 20aa97a1..fabd92a1 100644
--- a/src/luarocks/cmd/init.lua
+++ b/src/luarocks/cmd/init.lua
@@ -125,10 +125,6 @@ function init.command(args)
 
    util.title("Initializing project '" .. args.name .. "' for Lua " .. cfg.lua_version .. " ...")
 
-   util.printout("Checking your Lua installation ...")
-   if not cfg.lua_found then
-      return nil, "Lua installation is not found."
-   end
    local ok, err = deps.check_lua_incdir(cfg.variables)
    if not ok then
       return nil, err
diff --git a/src/luarocks/core/cfg.lua b/src/luarocks/core/cfg.lua
index 2e144c62..a420bb44 100644
--- a/src/luarocks/core/cfg.lua
+++ b/src/luarocks/core/cfg.lua
@@ -787,7 +787,7 @@ function cfg.init(detected, warning)
    -- if only cfg.variables.LUA is given in config files,
    -- derive LUA_BINDIR and LUA_DIR from them.
    if cfg.variables.LUA and not cfg.variables.LUA_BINDIR then
-      cfg.variables.LUA_BINDIR = cfg.variables.LUA:gsub("^(.*)[/\\][^/\\]*$")
+      cfg.variables.LUA_BINDIR = cfg.variables.LUA:match("^(.*)[/\\][^/\\]*$")
       if not cfg.variables.LUA_DIR then
          cfg.variables.LUA_DIR = cfg.variables.LUA_BINDIR:gsub("[/\\]bin$", "") or cfg.variables.LUA_BINDIR
       end
diff --git a/src/luarocks/deps.lua b/src/luarocks/deps.lua
index 2680b64b..16631c58 100644
--- a/src/luarocks/deps.lua
+++ b/src/luarocks/deps.lua
@@ -706,7 +706,7 @@ local function lua_h_exists(d, luaver)
       return nil, "Lua header found at " .. d .. " does not match Lua version " .. luaver .. ". You may want to override this by configuring LUA_INCDIR.", "dependency", 2
    end
 
-   return nil, "Failed finding Lua header files. You may need to install them or configure LUA_INCDIR.", "dependency", 1
+   return nil, "Failed finding Lua header files (searched at " .. d .. "). You may need to install them or configure LUA_INCDIR.", "dependency", 1
 end
 
 local function find_lua_incdir(prefix, luaver, luajitver)
@@ -763,7 +763,7 @@ function deps.check_lua_incdir(vars)
       return nil, err
    end
 
-   return nil, "Failed finding Lua header files. You may need to install them or configure LUA_INCDIR.", "dependency"
+   return nil, "Failed finding Lua headers; neither LUA_DIR or LUA_INCDIR are set. You may need to install them or configure LUA_INCDIR.", "dependency"
 end
 
 function deps.check_lua_libdir(vars)
@@ -789,6 +789,7 @@ function deps.check_lua_libdir(vars)
    }
    if ljv then
       table.insert(libnames, 1, "luajit-" .. cfg.lua_version)
+      table.insert(libnames, 2, "luajit")
    end
    local cache = {}
    local save_LUA_INCDIR = vars.LUA_INCDIR
diff --git a/src/luarocks/util.lua b/src/luarocks/util.lua
index 902656fd..de9157fc 100644
--- a/src/luarocks/util.lua
+++ b/src/luarocks/util.lua
@@ -434,6 +434,10 @@ do
       end
       cfg.cache.luajit_version_checked = true
 
+      if not cfg.variables.LUA then
+         return nil
+      end
+
       local ljv
       if cfg.lua_version == "5.1" then
          -- Ignores extra version info for custom builds, e.g. "LuaJIT 2.1.0-beta3 some-other-version-info"