Add Lua 5.1 to rockspec

[javalikescript]

Fix #8

[s-ol]

Hey, this is almost right but the define should switch at 5.2, not 5.3. Compiling for 5.2 as is it picks the lua 5.1 version and fails:

$ luarocks --lua-version=5.2 make luachild-scm-1.rockspec 
gcc -O2 -fPIC -I/usr/include/lua5.2 -c luachild_common.c -o luachild_common.o -DUSE_POSIX -I./
gcc -O2 -fPIC -I/usr/include/lua5.2 -c luachild_lua_5_3.c -o luachild_lua_5_3.o -DUSE_POSIX -I./
gcc -O2 -fPIC -I/usr/include/lua5.2 -c luachild_lua_5_1.c -o luachild_lua_5_1.o -DUSE_POSIX -I./
luachild_lua_5_1.c: In function ‘lua_value_length’:
luachild_lua_5_1.c:19:10: error: implicit declaration of function ‘lua_objlen’; did you mean ‘lua_len’? [-Wimplicit-function-declaration]
   19 |   return lua_objlen(L, index);
      |          ^~~~~~~~~~
      |          lua_len

Error: Build error: Failed compiling object luachild_lua_5_1.o

I'd suggest renaming luachild_lua_5_3.c to luachild_lua_5_2.c and adjusting the ifdefs as follows:

diff --git a/luachild_lua_5_1.c b/luachild_lua_5_1.c
index c4ca9de..bfdea1b 100644
--- a/luachild_lua_5_1.c
+++ b/luachild_lua_5_1.c
@@ -1,6 +1,6 @@
 #include "luachild.h"
 #ifdef USE_LUAPUC
-#if LUA_VERSION_NUM < 503
+#if LUA_VERSION_NUM < 502
 
 #include <stdio.h>
 #include <errno.h>
diff --git a/luachild_lua_5_3.c b/luachild_lua_5_2.c
similarity index 97%
rename from luachild_lua_5_3.c
rename to luachild_lua_5_2.c
index 24ee272..acde7d4 100644
--- a/luachild_lua_5_3.c
+++ b/luachild_lua_5_2.c
@@ -1,6 +1,6 @@
 #include "luachild.h"
 #ifdef USE_LUAPUC
-#if LUA_VERSION_NUM > 502
+#if LUA_VERSION_NUM >= 502
 
 #include <stdio.h>
 #include <errno.h>
diff --git a/luachild-scm-1.rockspec b/luachild-scm-1.rockspec
index 75a7efd..d2ce5a4 100644
--- a/luachild-scm-1.rockspec
+++ b/luachild-scm-1.rockspec
@@ -29,7 +29,7 @@ build = {
         ["luachild"] = {
           defines = { "USE_POSIX" },
           incdirs = { "./" },
-          sources = { "luachild_common.c", "luachild_lua_5_3.c", "luachild_lua_5_1.c", "luachild_luajit_2_1.c", "luachild_posix.c", "luachild_windows.c", }
+          sources = { "luachild_common.c", "luachild_lua_5_2.c", "luachild_lua_5_1.c", "luachild_luajit_2_1.c", "luachild_posix.c", "luachild_windows.c", }
         },
       },
     },
@@ -39,7 +39,7 @@ build = {
         ["luachild"] = {
           defines = { "USE_WINDOWS" },
           incdirs = { "./" },
-          sources = { "luachild_common.c", "luachild_lua_5_3.c", "luachild_lua_5_1.c", "luachild_luajit_2_1.c", "luachild_posix.c", "luachild_windows.c", }
+          sources = { "luachild_common.c", "luachild_lua_5_2.c", "luachild_lua_5_1.c", "luachild_luajit_2_1.c", "luachild_posix.c", "luachild_windows.c", }
         },
       },
     },

(the < / >= makes the mechanism clearer too, IMHO)

With this change applied, it builds all versions from Lua 5.1 to 5.5 for me.

[s-ol]

@javalikescript this should be >= 502, otherwise Lua 5.2 is left with no implementation at all

[s-ol]

lua 5.2 already works, just compile it as 5.3, there is no difference in the C API used by this library

[javalikescript]

Done in commit 8500dc9