fix(lua): compare float with int strictly in equality (#7611)

Co-authored-by: Peter Feerick <peter.feerick@gmail.com>
Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>

radio/src/tests/lua.cpp

@@ -198,6 +198,46 @@ TEST(Lua, Switches)
 #endif
 }
 
+TEST(Lua, testFloatIntegerEquality)
+{
+  // 0.5 is not an integer, so it must not equal 0 (regression #7587)
+  // both directions asserted explicitly so the intent is obvious at a glance
+  luaExecStr("if 0.5 == 0 then error('0.5 == 0') end");
+  luaExecStr("if not (0.5 ~= 0) then error('0.5 ~= 0') end");
+  luaExecStr("if 0.50 == 0 then error('0.50 == 0') end");
+  luaExecStr("if not (0.50 ~= 0) then error('0.50 ~= 0') end");
+  luaExecStr("if 0.50 == 0.0 then error('0.50 == 0.0') end");
+  // ... even when the value comes from a variable, as in the reported issue
+  luaExecStr("local v = 0.50; if v == 0 then error('v == 0') end");
+  luaExecStr("local v = 0.50; if not (v ~= 0) then error('v ~= 0') end");
+  // negative non-integral floats must not equal integers either
+  luaExecStr("if -0.5 == 0 then error('-0.5 == 0') end");
+  luaExecStr("if not (-0.5 ~= 0) then error('-0.5 ~= 0') end");
+  luaExecStr("if not (-0.5 < 0) then error('-0.5 < 0') end");
+  luaExecStr("if -0.5 > 0 then error('-0.5 > 0') end");
+  // integral floats still compare equal to their integer counterpart
+  luaExecStr("if 1.0 ~= 1 then error('1.0 ~= 1') end");
+  luaExecStr("if 0.0 ~= 0 then error('0.0 ~= 0') end");
+  luaExecStr("if -1.0 ~= -1 then error('-1.0 ~= -1') end");
+  // order comparisons on the same values must remain consistent
+  luaExecStr("if not (0.5 >= 0) then error('0.5 >= 0') end");
+  luaExecStr("if 0.5 <= 0 then error('0.5 <= 0') end");
+  luaExecStr("if not (0.5 > 0) then error('0.5 > 0') end");
+  luaExecStr("if 0.5 < 0 then error('0.5 < 0') end");
+  luaExecStr("if not (0.50 >= 0) then error('0.50 >= 0') end");
+  luaExecStr("if 0.50 <= 0 then error('0.50 <= 0') end");
+  luaExecStr("if not (1.0 >= 1) then error('1.0 >= 1') end");
+  luaExecStr("if not (1.0 <= 1) then error('1.0 <= 1') end");
+  luaExecStr("if not (0.0 >= 0) then error('0.0 >= 0') end");
+  luaExecStr("if not (0.0 <= 0) then error('0.0 <= 0') end");
+  // mixed arithmetic must still yield floats; the fix only affects equality
+  luaExecStr("if math.type(0.5 + 0) ~= 'float' then error('0.5 + 0') end");
+  luaExecStr("if math.type(1.0 + 1) ~= 'float' then error('1.0 + 1') end");
+  luaExecStr("if math.type(1 / 2) ~= 'float' then error('1 / 2') end");
+  luaExecStr("if math.type(7.5 % 2) ~= 'float' then error('7.5 % 2') end");
+  luaExecStr("if math.type(0.5 * 2) ~= 'float' then error('0.5 * 2') end");
+}
+
 TEST(Lua, testLegacyNames)
 {
   MODEL_RESET();

radio/src/thirdparty/Lua/src/lvm.c

@@ -401,7 +401,7 @@ int luaV_equalobj (lua_State *L, const TValue *t1, const TValue *t2) {
       return 0;  /* only numbers can be equal with different variants */
     else {  /* two numbers with different variants */
       lua_Integer i1, i2;  /* compare them as integers */
-      return (tointeger(t1, &i1) && tointeger(t2, &i2) && i1 == i2);
+      return (tointegerexact(t1, &i1) && tointegerexact(t2, &i2) && i1 == i2);
     }
   }
   /* values have same type and same variant */

radio/src/thirdparty/Lua/src/lvm.h

@@ -43,6 +43,15 @@
 #define tointeger(o,i) \
     (ttisinteger(o) ? (*(i) = ivalue(o), 1) : luaV_tointeger(o,i,LUA_FLOORN2I))
 
+/* non-soft conversion: only integral values are converted.
+** This is the strict semantic used by equality ('==' and '~='), where a
+** non-integral float such as 0.5 must not compare equal to an integer.
+** 'tointeger' (soft, LUA_FLOORN2I) is intentionally kept for API argument
+** coercion so that EdgeTX API functions accept unrounded floats; do not
+** switch this macro back to the soft conversion. */
+#define tointegerexact(o,i) \
+    (ttisinteger(o) ? (*(i) = ivalue(o), 1) : luaV_tointeger(o,i,0))
+
 #define intop(op,v1,v2) l_castU2S(l_castS2U(v1) op l_castS2U(v2))
 
 #define luaV_rawequalobj(t1,t2)		luaV_equalobj(NULL,t1,t2)