fix(build): don't look for Lua headers when installing pure-Lua rocks

This only applies to 'builtin' as we can't know about other modes,
but this should be good enough.

Fixes #1275.

4 files changed, 85 insertions, 57 deletions

diff --git a/src/luarocks/build.lua b/src/luarocks/build.lua
index 471de427..55242e60 100644
--- a/src/luarocks/build.lua
+++ b/src/luarocks/build.lua
@@ -111,18 +111,6 @@ local function process_dependencies(rockspec, opts)
       end
    end
 
-   local ok, err, errcode = deps.check_lua_incdir(rockspec.variables)
-   if not ok then
-      return nil, err, errcode
-   end
-
-   if cfg.link_lua_explicitly then
-      local ok, err, errcode = deps.check_lua_libdir(rockspec.variables)
-      if not ok then
-         return nil, err, errcode
-      end
-   end
-
    if opts.deps_mode == "none" then
       return true
    end
@@ -165,11 +153,8 @@ local function process_dependencies(rockspec, opts)
          end
       end
    end
-   ok, err, errcode = deps.fulfill_dependencies(rockspec, "dependencies", opts.deps_mode, opts.verify)
-   if err then
-      return nil, err, errcode
-   end
-   return true
+
+   return deps.fulfill_dependencies(rockspec, "dependencies", opts.deps_mode, opts.verify)
 end
 
 local function fetch_and_change_to_source_dir(rockspec, opts)
@@ -241,6 +226,21 @@ local function run_build_driver(rockspec, no_install)
    if not pok or type(driver) ~= "table" then
       return nil, "Failed initializing build back-end for build type '"..btype.."': "..driver
    end
+
+   if not driver.skip_lua_inc_lib_check then
+      local ok, err, errcode = deps.check_lua_incdir(rockspec.variables)
+      if not ok then
+         return nil, err, errcode
+      end
+
+      if cfg.link_lua_explicitly then
+         local ok, err, errcode = deps.check_lua_libdir(rockspec.variables)
+         if not ok then
+            return nil, err, errcode
+         end
+      end
+   end
+
    local ok, err = driver.run(rockspec, no_install)
    if not ok then
       return nil, "Build error: " .. err
diff --git a/src/luarocks/build/builtin.lua b/src/luarocks/build/builtin.lua
index 70210bab..c55b61a0 100644
--- a/src/luarocks/build/builtin.lua
+++ b/src/luarocks/build/builtin.lua
@@ -2,6 +2,11 @@
 --- A builtin build system: back-end to provide a portable way of building C-based Lua modules.
 local builtin = {}
 
+-- This build driver checks LUA_INCDIR and LUA_LIBDIR on demand,
+-- so that pure-Lua rocks don't need to have development headers
+-- installed.
+builtin.skip_lua_inc_lib_check = true
+
 local unpack = unpack or table.unpack
 
 local fs = require("luarocks.fs")
@@ -9,38 +14,7 @@ local path = require("luarocks.path")
 local util = require("luarocks.util")
 local cfg = require("luarocks.core.cfg")
 local dir = require("luarocks.dir")
-
-function builtin.autodetect_external_dependencies(build)
-   if not build or not build.modules then
-      return nil
-   end
-   local extdeps = {}
-   local any = false
-   for _, data in pairs(build.modules) do
-      if type(data) == "table" and data.libraries then
-         local libraries = data.libraries
-         if type(libraries) == "string" then
-            libraries = { libraries }
-         end
-         local incdirs = {}
-         local libdirs = {}
-         for _, lib in ipairs(libraries) do
-            local upper = lib:upper():gsub("%+", "P"):gsub("[^%w]", "_")
-            any = true
-            extdeps[upper] = { library = lib }
-            table.insert(incdirs, "$(" .. upper .. "_INCDIR)")
-            table.insert(libdirs, "$(" .. upper .. "_LIBDIR)")
-         end
-         if not data.incdirs then
-            data.incdirs = incdirs
-         end
-         if not data.libdirs then
-            data.libdirs = libdirs
-         end
-      end
-   end
-   return any and extdeps or nil
-end
+local deps = require("luarocks.deps")
 
 local function autoextract_libs(external_dependencies, variables)
    if not external_dependencies then
@@ -323,10 +297,16 @@ function builtin.run(rockspec, no_install)
       end
       if type(info) == "table" then
          if not checked_lua_h then
-            local lua_incdir, lua_h = variables.LUA_INCDIR, "lua.h"
-            if not fs.exists(dir.path(lua_incdir, lua_h)) then
-               return nil, "Lua header file "..lua_h.." not found (looked in "..lua_incdir.."). \n" ..
-                           "You need to install the Lua development package for your system."
+            local ok, err, errcode = deps.check_lua_incdir(rockspec.variables)
+            if not ok then
+               return nil, err, errcode
+            end
+
+            if cfg.link_lua_explicitly then
+               local ok, err, errcode = deps.check_lua_libdir(rockspec.variables)
+               if not ok then
+                  return nil, err, errcode
+               end
             end
             checked_lua_h = true
          end
diff --git a/src/luarocks/cmd.lua b/src/luarocks/cmd.lua
index 3cbe3852..3067f4ce 100644
--- a/src/luarocks/cmd.lua
+++ b/src/luarocks/cmd.lua
@@ -561,7 +561,7 @@ function cmd.run_command(description, commands, external_namespace, ...)
             util.warning("command module " .. module .. " does not implement command(), skipping")
          end
       else
-         util.warning("failed to load command module " .. module)
+         util.warning("failed to load command module " .. module .. ": " .. mod)
       end
    end
 
diff --git a/src/luarocks/deps.lua b/src/luarocks/deps.lua
index 8af28327..2680b64b 100644
--- a/src/luarocks/deps.lua
+++ b/src/luarocks/deps.lua
@@ -10,7 +10,6 @@ local fun = require("luarocks.fun")
 local util = require("luarocks.util")
 local vers = require("luarocks.core.vers")
 local queries = require("luarocks.queries")
-local builtin = require("luarocks.build.builtin")
 local deplocks = require("luarocks.deplocks")
 
 --- Generate a function that matches dep queries against the manifest,
@@ -570,6 +569,40 @@ local function check_external_dependency(name, ext_files, vars, mode, cache)
    return nil, err_dirname, err_testfile, err_files
 end
 
+function deps.autodetect_external_dependencies(build)
+   -- only applies to the 'builtin' build type
+   if not build or not build.modules then
+      return nil
+   end
+
+   local extdeps = {}
+   local any = false
+   for _, data in pairs(build.modules) do
+      if type(data) == "table" and data.libraries then
+         local libraries = data.libraries
+         if type(libraries) == "string" then
+            libraries = { libraries }
+         end
+         local incdirs = {}
+         local libdirs = {}
+         for _, lib in ipairs(libraries) do
+            local upper = lib:upper():gsub("%+", "P"):gsub("[^%w]", "_")
+            any = true
+            extdeps[upper] = { library = lib }
+            table.insert(incdirs, "$(" .. upper .. "_INCDIR)")
+            table.insert(libdirs, "$(" .. upper .. "_LIBDIR)")
+         end
+         if not data.incdirs then
+            data.incdirs = incdirs
+         end
+         if not data.libdirs then
+            data.libdirs = libdirs
+         end
+      end
+   end
+   return any and extdeps or nil
+end
+
 --- Set up path-related variables for external dependencies.
 -- For each key in the external_dependencies table in the
 -- rockspec file, four variables are created: <key>_DIR, <key>_BINDIR,
@@ -587,7 +620,7 @@ function deps.check_external_deps(rockspec, mode)
    assert(rockspec:type() == "rockspec")
 
    if not rockspec.external_dependencies then
-      rockspec.external_dependencies = builtin.autodetect_external_dependencies(rockspec.build)
+      rockspec.external_dependencies = deps.autodetect_external_dependencies(rockspec.build)
    end
    if not rockspec.external_dependencies then
       return true
@@ -706,16 +739,25 @@ local function find_lua_incdir(prefix, luaver, luajitver)
 end
 
 function deps.check_lua_incdir(vars)
+   if vars.LUA_INCDIR_OK == true
+      then return true
+   end
+
    local ljv = util.get_luajit_version()
 
    if vars.LUA_INCDIR then
-      return lua_h_exists(vars.LUA_INCDIR, cfg.lua_version)
+      local ok, err = lua_h_exists(vars.LUA_INCDIR, cfg.lua_version)
+      if ok then
+         vars.LUA_INCDIR_OK = true
+      end
+      return ok, err
    end
 
    if vars.LUA_DIR then
       local d, err = find_lua_incdir(vars.LUA_DIR, cfg.lua_version, ljv)
       if d then
          vars.LUA_INCDIR = d
+         vars.LUA_INCDIR_OK = true
          return true
       end
       return nil, err
@@ -725,10 +767,15 @@ function deps.check_lua_incdir(vars)
 end
 
 function deps.check_lua_libdir(vars)
+   if vars.LUA_LIBDIR_OK == true
+      then return true
+   end
+
    local fs = require("luarocks.fs")
    local ljv = util.get_luajit_version()
 
    if vars.LUA_LIBDIR and vars.LUALIB and fs.exists(dir.path(vars.LUA_LIBDIR, vars.LUALIB)) then
+      vars.LUA_LIBDIR_OK = true
       return true
    end
 
@@ -768,6 +815,7 @@ function deps.check_lua_libdir(vars)
 
    if ok then
       vars.LUALIB = vars.LUA_LIBDIR_FILE
+      vars.LUA_LIBDIR_OK = true
       return true
    else
       err = err or "Failed finding Lua library. You may need to configure LUA_LIBDIR."