tweak

esphome/components/esp8266/remove_float_scanf.py.script

@@ -1,21 +1,28 @@
 # pylint: disable=E0602
 Import("env")  # noqa
 
-# Remove float scanf support from linker flags
+# Remove forced scanf linkage to allow garbage collection of unused code
-# The Arduino ESP8266 framework unconditionally adds:
-#   -u _printf_float -u _scanf_float
-# ESPHome doesn't use scanf with %f, so _scanf_float is not needed.
 #
-# Savings:
+# The ESP8266 Arduino framework unconditionally adds:
-#   - _scanf_float: ~1.3KB
+#   -u _printf_float -u _scanf_float
-#   - _strtod_l: ~3.7KB (string-to-double, only needed by scanf float)
+#
-#   - Related float parsing helpers
+# The -u flag forces symbols to be linked even if unreferenced, which pulls
+# in the entire scanf family (~7-8KB). ESPHome doesn't use scanf at all
+# (verified by CI check in PR #13657), so this is pure dead weight.
+#
+# By removing -u _scanf_float, --gc-sections can eliminate:
+#   - scanf family functions (~7KB)
+#   - _strtod_l (~3.7KB)
+#   - Related parsing infrastructure
+#
+# We keep -u _printf_float because components still use %f in logging.
 
 
 def remove_scanf_float_flag(source, target, env):
     """Remove -u _scanf_float from linker flags.
 
-    This is called as a pre-action before the link step.
+    This is called as a pre-action before the link step, after the
+    Arduino framework has added its default flags.
     """
     linkflags = env.get("LINKFLAGS", [])
     new_linkflags = []
@@ -26,7 +33,7 @@ def remove_scanf_float_flag(source, target, env):
         if flag == "-u" and i + 1 < len(linkflags):
             next_flag = linkflags[i + 1]
             if next_flag == "_scanf_float":
-                print("ESPHome: Removing float scanf support (_scanf_float)")
+                print("ESPHome: Removing _scanf_float (saves ~8KB flash)")
                 i += 2  # Skip both -u and the symbol
                 continue
         new_linkflags.append(flag)