build(core): improve model detection

instead of MODEL_IS_T2B1, we now catch INTERNAL_MODEL == Txyz

this is still not perfect because it can't detect 'in'/'not in', which
sucks but what can we do

core/site_scons/site_tools/micropython/__init__.py

@@ -42,16 +42,13 @@ def generate(env):
         # replace "utils.BITCOIN_ONLY" with literal constant (True/False)
         # so the compiler can optimize out the things we don't want
         btc_only = env["bitcoin_only"] == "1"
-        is_t2b1 = env["TREZOR_MODEL"] == "R"
         backlight = env["backlight"]
         optiga = env["optiga"]
         layout_tt = env["ui_layout"] == "UI_LAYOUT_TT"
         layout_tr = env["ui_layout"] == "UI_LAYOUT_TR"
         thp = env["thp"]
         interim = f"{target[:-4]}.i"  # replace .mpy with .i
-        sed_scripts = " ".join(
+        sed_scripts = [
-            [
-                rf"-e 's/utils\.MODEL_IS_T2B1/{is_t2b1}/g'",
             rf"-e 's/utils\.BITCOIN_ONLY/{btc_only}/g'",
             rf"-e 's/utils\.USE_BACKLIGHT/{backlight}/g'",
             rf"-e 's/utils\.USE_OPTIGA/{optiga}/g'",
@@ -63,8 +60,23 @@ def generate(env):
             r"-e '/from typing import (/,/^\s*)/ {s/^/# /; }'",
             r"-e 's/from typing import/# \0/'",
         ]
+
+        MODEL_SYMS = {
+            "T": "T2T1",
+            "R": "T2B1",
+            "T3T1": "T3T1",
+        }
+
+        for model_sym, internal_model in MODEL_SYMS.items():
+            model_matches = env["TREZOR_MODEL"] == model_sym
+            sed_scripts.extend(
+                (
+                    rf"-e 's/utils\.INTERNAL_MODEL == \"{internal_model}\"/{model_matches}/g'",
+                    rf"-e 's/utils\.INTERNAL_MODEL != \"{internal_model}\"/{not model_matches}/g'",
                 )
-        return f"$SED {sed_scripts} {source} > {interim} && $MPY_CROSS -o {target} -s {source_name} {interim}"
+            )
+
+        return f"$SED {' '.join(sed_scripts)} {source} > {interim} && $MPY_CROSS -o {target} -s {source_name} {interim}"
 
     env["BUILDERS"]["FrozenModule"] = SCons.Builder.Builder(
         generator=generate_frozen_module,

core/src/apps/base.py

@@ -126,8 +126,8 @@ def get_features() -> Features:
             Capability.Translations,
         ]
 
-        # We do not support some currencies on T2B1
+        # We don't support some currencies on later models (see #2793)
-        if not utils.MODEL_IS_T2B1:
+        if utils.INTERNAL_MODEL == "T2T1":
             f.capabilities.extend(
                 [
                     Capability.NEM,

core/src/trezor/utils.py

@@ -30,10 +30,6 @@ from trezorutils import (  # noqa: F401
 )
 from typing import TYPE_CHECKING
 
-# Will get replaced by "True" / "False" in the build process
-# However, needs to stay as an exported symbol for the unit tests
-MODEL_IS_T2B1: bool = INTERNAL_MODEL == "T2B1"
-
 DISABLE_ANIMATION = 0
 
 if __debug__:

core/tests/test_apps.bitcoin.signtx_decred.py

@@ -1,6 +1,6 @@
 from common import *  # isort:skip
 
-if not utils.MODEL_IS_T2B1:
+if utils.INTERNAL_MODEL not in ("T2B1", "T3T1"):
     from trezor.crypto import bip39
     from trezor.enums import AmountUnit, OutputScriptType
     from trezor.enums.RequestType import TXFINISHED, TXINPUT, TXMETA, TXOUTPUT
@@ -405,5 +405,5 @@ class TestSignTxDecred(unittest.TestCase):
 
 
 if __name__ == "__main__":
-    if not utils.MODEL_IS_T2B1:
+    if utils.INTERNAL_MODEL not in ("T2B1", "T3T1"):
         unittest.main()

core/tests/test_apps.common.coins.py

@@ -22,7 +22,7 @@ class TestCoins(unittest.TestCase):
             ("ZEC", "Zcash", 7352),
             ("TAZ", "Zcash Testnet", 7461),
         ]
-        if not utils.MODEL_IS_T2B1:
+        if utils.INTERNAL_MODEL not in ("T2B1", "T3T1"):
             ref.extend(
                 [
                     ("NMC", "Namecoin", 52),