fix: advise only a core that --core accepts

The size hint drew from every core of the system and named ares, which
loads no file of its own, so --core ares was refused. It now picks among
the names --core resolves against.

install.ps1

@@ -11,7 +11,7 @@
 
     $ErrorActionPreference = "Stop"
     $defaultInstallUrl = "https://raw.githubusercontent.com/Abdess/retrobios/main/install.py"
-    $defaultInstallSha256 = "1238dfb08b3168992cf4e390358540c6c1bbadf23ae5b74fb34e9101a2a083ef"
+    $defaultInstallSha256 = "853300c169f08b2554a421aac33da1b5004d3eedd70ae9dec1d732766d06b1ca"
     $maximumInstallerBytes = 2MB
     $installerExit = 0
     $installer = if ($PSScriptRoot) { Join-Path $PSScriptRoot "install.py" } else { $null }

install.py

@@ -40,7 +40,7 @@ import urllib.request
 import xml.etree.ElementTree as ET
 import zipfile
 import zlib
-from collections.abc import Callable, Iterator
+from collections.abc import Callable, Collection, Iterator
 from pathlib import Path, PurePosixPath
 from typing import BinaryIO, NamedTuple, TextIO
 
@@ -6607,11 +6607,15 @@ def _bytes(files: list[dict]) -> int:
 
 def bulk_hint(
     to_download: list[dict], manifest: dict, systems_chosen: bool, cores_chosen: bool,
+    accepted: Collection[str] = (),
 ) -> list[str]:
     """Name what pulls most of a download, when narrowing saves over half of it.
 
     `--system 3do` fetched 349 MB for RetroArch, and `--core opera` 12.5 MB:
     the arcade cores that also read 3DO pulled the rest, and nothing said so.
+    accepted holds the names --core takes. Drawn from every core of the
+    system, the advice named ares, which loads no file of its own, and
+    `--core ares` was then refused.
     """
     total = _bytes(to_download)
     if total < BULK_HINT_FROM:
@@ -6619,7 +6623,8 @@ def bulk_hint(
     systems = {s for entry in to_download for s in entry_systems(entry)}
     if not cores_chosen and len(systems) == 1:
         system = next(iter(systems))
-        candidates = (manifest.get("system_cores") or {}).get(system) or []
+        candidates = [core for core in (manifest.get("system_cores") or {}).get(system) or []
+                      if core in accepted]
         by_core: dict[str, int] = {}
         for entry in to_download:
             for core in entry.get("cores") or []:
@@ -7465,6 +7470,8 @@ def _install(args: argparse.Namespace, real_stdout: TextIO) -> None:
                 args.emulator, manifest, plat_name, files, omitted_files
             )
 
+        # What --core resolves against, for advice that names one.
+        core_choices = set(available_choices(files, omitted_files)["cores"])
         selection = _requested_narrowing(args, plat_name, files, omitted_files, manifest)
         if (
             selection is None
@@ -7577,6 +7584,7 @@ def _install(args: argparse.Namespace, real_stdout: TextIO) -> None:
             systems_chosen=bool(selection and selection[0]),
             cores_chosen=bool((selection and selection[1]) or args.emulator
                               or args.installed_cores or target),
+            accepted=core_choices,
         )
 
         narrowed = bool(

install.sh

@@ -18,7 +18,7 @@ esac
 TEMP_INSTALLER=""
 TEMP_DIRECTORY=""
 DEFAULT_INSTALL_URL="https://raw.githubusercontent.com/Abdess/retrobios/main/install.py"
-DEFAULT_INSTALL_SHA256="1238dfb08b3168992cf4e390358540c6c1bbadf23ae5b74fb34e9101a2a083ef"
+DEFAULT_INSTALL_SHA256="853300c169f08b2554a421aac33da1b5004d3eedd70ae9dec1d732766d06b1ca"
 MAX_INSTALLER_BYTES=2097152
 
 cleanup() {

tests/test_install_offline.py

@@ -477,12 +477,33 @@ class TheSummaryNamesTheBulk(unittest.TestCase):
             _sized("mame/3do_m2.zip", 37 * MB, ["3do"], ["mame"]),
         ]
         lines = install.bulk_hint(files, {"system_cores": {"3do": ["mame", "opera"]}},
-                                  systems_chosen=True, cores_chosen=False)
+                                  systems_chosen=True, cores_chosen=False,
+                                  accepted={"mame", "opera"})
         self.assertEqual(lines, [
             "  mame pulls 337.0 MB of this 349.0 MB download for 3do. --core opera "
             "keeps 12.0 MB of it and saves 337.0 MB (96%)."
         ])
 
+    def test_only_a_core_the_option_accepts_is_advised(self):
+        """`--core ares keeps 11.0 MB` was printed, and `--core ares` then
+        answered "unknown core": ares emulates the PlayStation and loads no
+        file of its own, and --core takes only the cores that do."""
+        files = [
+            _sized("scph5501.bin", 1 * MB, ["sony-playstation"]),
+            _sized("ps2_bios.bin", 300 * MB, ["sony-playstation"], ["duckstation"]),
+            _sized("pcsx/extra.bin", 2 * MB, ["sony-playstation"], ["pcsx_rearmed"]),
+        ]
+        manifest = {"system_cores": {"sony-playstation": ["ares", "duckstation",
+                                                          "pcsx_rearmed"]}}
+        lines = install.bulk_hint(files, manifest, True, False,
+                                  accepted={"duckstation", "pcsx_rearmed"})
+        self.assertEqual(len(lines), 1)
+        self.assertIn("--core pcsx_rearmed keeps 3.0 MB", lines[0])
+        self.assertNotIn("ares", lines[0])
+        self.assertEqual(install.bulk_hint(files, manifest, True, False,
+                                           accepted={"duckstation"}), [])
+        self.assertEqual(install.bulk_hint(files, manifest, True, False), [])
+
     def test_a_system_pulling_most_of_the_download_is_named(self):
         files = [_sized("a.zip", 400 * MB, ["arcade"]), _sized("b.bin", 50 * MB, ["nes"]),
                  _sized("c.bin", 10 * MB, ["gba"])]