perf: cache recent decoded map tiles

tests/native/test_decoded_tile_cache.py

@@ -0,0 +1,41 @@
+"""Compile the fixed decoded-tile LRU as strict C++11 under ASan/UBSan."""
+from __future__ import annotations
+
+import os
+from pathlib import Path
+import subprocess
+
+from native_test import find_cxx
+
+HERE = Path(__file__).resolve().parent
+ROOT = HERE.parents[1]
+
+
+def test_decoded_tile_cache_cpp11_sanitized(tmp_path):
+    binary = tmp_path / "test_decoded_tile_cache"
+    command = [
+        find_cxx(),
+        "-std=c++11",
+        "-Wall",
+        "-Wextra",
+        "-Werror",
+        "-pedantic",
+        "-fsanitize=address,undefined",
+        "-fno-omit-frame-pointer",
+        f"-I{ROOT / 'lib/tdeck_ui'}",
+        str(HERE / "test_decoded_tile_cache.cpp"),
+        str(ROOT / "lib/tdeck_ui/UI/LXMF/DecodedTileCache.cpp"),
+        "-o",
+        str(binary),
+    ]
+    compiled = subprocess.run(command, capture_output=True, text=True, timeout=60)
+    assert compiled.returncode == 0, compiled.stdout + compiled.stderr
+    env = os.environ.copy()
+    env["ASAN_OPTIONS"] = "detect_leaks=1:halt_on_error=1"
+    env["UBSAN_OPTIONS"] = "halt_on_error=1:print_stacktrace=1"
+    ran = subprocess.run(
+        [str(binary)], capture_output=True, text=True, timeout=60, env=env
+    )
+    assert ran.returncode == 0, ran.stdout + ran.stderr
+    assert "decoded tile cache:" in ran.stdout
+    assert "0 failed" in ran.stdout