fix: enum discriminant overflow (#1185)

Author: Salka1988

packages/fuels-macros/src/derive/utils.rs

@@ -60,10 +60,10 @@ pub(crate) fn extract_variants(
     contents: impl IntoIterator<Item = Variant>,
     fuels_core_path: TokenStream,
 ) -> Result<ExtractedVariants> {
-    let mut discriminant = 0;
     let variants = contents
         .into_iter()
-        .map(|variant| -> Result<_> {
+        .enumerate()
+        .map(|(discriminant, variant)| -> Result<_> {
             let is_unit = matches!(variant.fields, Fields::Unit);
             if has_ignore_attr(&variant.attrs) {
                 Ok(ExtractedVariant::Ignored {
@@ -75,15 +75,16 @@ pub(crate) fn extract_variants(
             } else {
                 validate_variant_type(&variant)?;
 
-                let current_discriminant = discriminant;
-                discriminant += 1;
+                let discriminant = discriminant.try_into().map_err(|_| {
+                    Error::new_spanned(&variant.ident, "Enums can not have more than 256 variants")
+                })?;
 
                 Ok(ExtractedVariant::Normal {
                     info: VariantInfo {
                         name: variant.ident,
                         is_unit,
                     },
-                    discriminant: current_discriminant,
+                    discriminant,
                 })
             }
         })

packages/fuels-macros/tests/ui/derive/tokenizable/enum_size_not_supported.rs

@@ -0,0 +1,264 @@
+use fuels_macros::Tokenizable;
+
+#[derive(Tokenizable)]
+enum MaxedOutVariantsEnum {
+    Variant0(u8),
+    Variant1(u8),
+    Variant2(u8),
+    Variant3(u8),
+    Variant4(u8),
+    Variant5(u8),
+    Variant6(u8),
+    Variant7(u8),
+    Variant8(u8),
+    Variant9(u8),
+    Variant10(u8),
+    Variant11(u8),
+    Variant12(u8),
+    Variant13(u8),
+    Variant14(u8),
+    Variant15(u8),
+    Variant16(u8),
+    Variant17(u8),
+    Variant18(u8),
+    Variant19(u8),
+    Variant20(u8),
+    Variant21(u8),
+    Variant22(u8),
+    Variant23(u8),
+    Variant24(u8),
+    Variant25(u8),
+    Variant26(u8),
+    Variant27(u8),
+    Variant28(u8),
+    Variant29(u8),
+    Variant30(u8),
+    Variant31(u8),
+    Variant32(u8),
+    Variant33(u8),
+    Variant34(u8),
+    Variant35(u8),
+    Variant36(u8),
+    Variant37(u8),
+    Variant38(u8),
+    Variant39(u8),
+    Variant40(u8),
+    Variant41(u8),
+    Variant42(u8),
+    Variant43(u8),
+    Variant44(u8),
+    Variant45(u8),
+    Variant46(u8),
+    Variant47(u8),
+    Variant48(u8),
+    Variant49(u8),
+    Variant50(u8),
+    Variant51(u8),
+    Variant52(u8),
+    Variant53(u8),
+    Variant54(u8),
+    Variant55(u8),
+    Variant56(u8),
+    Variant57(u8),
+    Variant58(u8),
+    Variant59(u8),
+    Variant60(u8),
+    Variant61(u8),
+    Variant62(u8),
+    Variant63(u8),
+    Variant64(u8),
+    Variant65(u8),
+    Variant66(u8),
+    Variant67(u8),
+    Variant68(u8),
+    Variant69(u8),
+    Variant70(u8),
+    Variant71(u8),
+    Variant72(u8),
+    Variant73(u8),
+    Variant74(u8),
+    Variant75(u8),
+    Variant76(u8),
+    Variant77(u8),
+    Variant78(u8),
+    Variant79(u8),
+    Variant80(u8),
+    Variant81(u8),
+    Variant82(u8),
+    Variant83(u8),
+    Variant84(u8),
+    Variant85(u8),
+    Variant86(u8),
+    Variant87(u8),
+    Variant88(u8),
+    Variant89(u8),
+    Variant90(u8),
+    Variant91(u8),
+    Variant92(u8),
+    Variant93(u8),
+    Variant94(u8),
+    Variant95(u8),
+    Variant96(u8),
+    Variant97(u8),
+    Variant98(u8),
+    Variant99(u8),
+    Variant100(u8),
+    Variant101(u8),
+    Variant102(u8),
+    Variant103(u8),
+    Variant104(u8),
+    Variant105(u8),
+    Variant106(u8),
+    Variant107(u8),
+    Variant108(u8),
+    Variant109(u8),
+    Variant110(u8),
+    Variant111(u8),
+    Variant112(u8),
+    Variant113(u8),
+    Variant114(u8),
+    Variant115(u8),
+    Variant116(u8),
+    Variant117(u8),
+    Variant118(u8),
+    Variant119(u8),
+    Variant120(u8),
+    Variant121(u8),
+    Variant122(u8),
+    Variant123(u8),
+    Variant124(u8),
+    Variant125(u8),
+    Variant126(u8),
+    Variant127(u8),
+    Variant128(u8),
+    Variant129(u8),
+    Variant130(u8),
+    Variant131(u8),
+    Variant132(u8),
+    Variant133(u8),
+    Variant134(u8),
+    Variant135(u8),
+    Variant136(u8),
+    Variant137(u8),
+    Variant138(u8),
+    Variant139(u8),
+    Variant140(u8),
+    Variant141(u8),
+    Variant142(u8),
+    Variant143(u8),
+    Variant144(u8),
+    Variant145(u8),
+    Variant146(u8),
+    Variant147(u8),
+    Variant148(u8),
+    Variant149(u8),
+    Variant150(u8),
+    Variant151(u8),
+    Variant152(u8),
+    Variant153(u8),
+    Variant154(u8),
+    Variant155(u8),
+    Variant156(u8),
+    Variant157(u8),
+    Variant158(u8),
+    Variant159(u8),
+    Variant160(u8),
+    Variant161(u8),
+    Variant162(u8),
+    Variant163(u8),
+    Variant164(u8),
+    Variant165(u8),
+    Variant166(u8),
+    Variant167(u8),
+    Variant168(u8),
+    Variant169(u8),
+    Variant170(u8),
+    Variant171(u8),
+    Variant172(u8),
+    Variant173(u8),
+    Variant174(u8),
+    Variant175(u8),
+    Variant176(u8),
+    Variant177(u8),
+    Variant178(u8),
+    Variant179(u8),
+    Variant180(u8),
+    Variant181(u8),
+    Variant182(u8),
+    Variant183(u8),
+    Variant184(u8),
+    Variant185(u8),
+    Variant186(u8),
+    Variant187(u8),
+    Variant188(u8),
+    Variant189(u8),
+    Variant190(u8),
+    Variant191(u8),
+    Variant192(u8),
+    Variant193(u8),
+    Variant194(u8),
+    Variant195(u8),
+    Variant196(u8),
+    Variant197(u8),
+    Variant198(u8),
+    Variant199(u8),
+    Variant200(u8),
+    Variant201(u8),
+    Variant202(u8),
+    Variant203(u8),
+    Variant204(u8),
+    Variant205(u8),
+    Variant206(u8),
+    Variant207(u8),
+    Variant208(u8),
+    Variant209(u8),
+    Variant210(u8),
+    Variant211(u8),
+    Variant212(u8),
+    Variant213(u8),
+    Variant214(u8),
+    Variant215(u8),
+    Variant216(u8),
+    Variant217(u8),
+    Variant218(u8),
+    Variant219(u8),
+    Variant220(u8),
+    Variant221(u8),
+    Variant222(u8),
+    Variant223(u8),
+    Variant224(u8),
+    Variant225(u8),
+    Variant226(u8),
+    Variant227(u8),
+    Variant228(u8),
+    Variant229(u8),
+    Variant230(u8),
+    Variant231(u8),
+    Variant232(u8),
+    Variant233(u8),
+    Variant234(u8),
+    Variant235(u8),
+    Variant236(u8),
+    Variant237(u8),
+    Variant238(u8),
+    Variant239(u8),
+    Variant240(u8),
+    Variant241(u8),
+    Variant242(u8),
+    Variant243(u8),
+    Variant244(u8),
+    Variant245(u8),
+    Variant246(u8),
+    Variant247(u8),
+    Variant248(u8),
+    Variant249(u8),
+    Variant250(u8),
+    Variant251(u8),
+    Variant252(u8),
+    Variant253(u8),
+    Variant254(u8),
+    Variant255(u8),
+    Variant256(u8),
+}
+
+fn main() {}

packages/fuels-macros/tests/ui/derive/tokenizable/enum_size_not_supported.stderr

@@ -0,0 +1,5 @@
+error: Enums can not have more than 256 variants
+   --> tests/ui/derive/tokenizable/enum_size_not_supported.rs:261:5
+    |
+261 |     Variant256(u8),
+    |     ^^^^^^^^^^