Add program_file to JLOptions and use for parsing project-at-script

As detailed in JuliaLang#55069, PROGRAM_FILE and ARGS are unset when
`load_path_expand` is first called during `Base.__init__()`, this
adds `program_file` to JLOptions as sets it during `jl_parse_opts`

Removed `unsafe_load_commands` path in `load_path_expand` as ARGS is
unset at this point.

base/initdefs.jl

@@ -284,22 +284,14 @@ function load_path_expand(env::AbstractString)::Union{String, Nothing}
         env == "@temp" && return mktempdir()
         env == "@stdlib" && return Sys.STDLIB
         if startswith(env, "@script")
-            if @isdefined(PROGRAM_FILE)
-                dir = dirname(PROGRAM_FILE)
-            else
-                cmds = unsafe_load_commands(JLOptions().commands)
-                if any(cmd::Pair{Char, String}->cmd_suppresses_program(first(cmd)), cmds)
-                    # Usage error. The user did not pass a script.
-                    return nothing
-                end
-                dir = dirname(ARGS[1])
-            end
-            if env == "@script"  # complete match, not startswith, so search upwards
-                return current_project(dir)
-            else
-                # starts with, so assume relative path is after
-                return abspath(replace(env, "@script" => dir))
-            end
+            program_file = JLOptions().program_file
+            program_file = program_file != C_NULL ? unsafe_string(program_file) : nothing
+            isnothing(program_file) && return nothing # User did not pass a script
+
+            # Expand trailing relative path 
+            dir = dirname(program_file)
+            dir = env != "@script" ? joinpath(dir, env[length("@script"):end]) : dir
+            return current_path(dir)
         end
         env = replace(env, '#' => VERSION.major, count=1)
         env = replace(env, '#' => VERSION.minor, count=1)

base/options.jl

@@ -17,6 +17,7 @@ struct JLOptions
     nprocs::Int32
     machine_file::Ptr{UInt8}
     project::Ptr{UInt8}
+    program_file::Ptr{UInt8}
     isinteractive::Int8
     color::Int8
     historyfile::Int8

src/jloptions.c

@@ -56,6 +56,7 @@ JL_DLLEXPORT void jl_init_options(void)
                         0,    // nprocs
                         NULL, // machine_file
                         NULL, // project
+                        NULL, // program_file 
                         0,    // isinteractive
                         0,    // color
                         JL_OPTIONS_HISTORYFILE_ON, // history file
@@ -969,6 +970,7 @@ JL_DLLEXPORT void jl_parse_opts(int *argcp, char ***argvp)
                       "This is a bug, please report it.", c);
         }
     }
+    jl_options.program_file = optind < argc ? strdup(argv[optind]) : "";
     parsing_args_done:
     jl_options.code_coverage = codecov;
     jl_options.malloc_log = malloclog;

src/jloptions.h

@@ -21,6 +21,7 @@ typedef struct {
     int32_t nprocs;
     const char *machine_file;
     const char *project;
+    const char *program_file;
     int8_t isinteractive;
     int8_t color;
     int8_t historyfile;