Enables where clauses for traits.

sway-core/src/semantic_analysis/ast_node/declaration/enum.rs

@@ -27,7 +27,7 @@ impl ty::TyEnumDecl {
         // Type check the type parameters. This will also insert them into the
         // current namespace.
         let new_type_parameters = check!(
-            TypeParameter::type_check_type_params(ctx.by_ref(), type_parameters, false),
+            TypeParameter::type_check_type_params(ctx.by_ref(), type_parameters),
             return err(warnings, errors),
             warnings,
             errors

sway-core/src/semantic_analysis/ast_node/declaration/function.rs

@@ -68,7 +68,7 @@ impl ty::TyFunctionDecl {
         // Type check the type parameters. This will also insert them into the
         // current namespace.
         let new_type_parameters = check!(
-            TypeParameter::type_check_type_params(ctx.by_ref(), type_parameters, false),
+            TypeParameter::type_check_type_params(ctx.by_ref(), type_parameters),
             return err(warnings, errors),
             warnings,
             errors
@@ -149,7 +149,7 @@ impl ty::TyFunctionDecl {
         check!(
             return_type
                 .type_id
-                .check_type_parameter_bounds(&ctx, &return_type.span),
+                .check_type_parameter_bounds(&ctx, &return_type.span, vec![]),
             return err(warnings, errors),
             warnings,
             errors

sway-core/src/semantic_analysis/ast_node/declaration/function/function_parameter.rs

@@ -43,7 +43,7 @@ impl ty::TyFunctionParameter {
         check!(
             type_argument
                 .type_id
-                .check_type_parameter_bounds(&ctx, &type_argument.span),
+                .check_type_parameter_bounds(&ctx, &type_argument.span, vec![]),
             return err(warnings, errors),
             warnings,
             errors

sway-core/src/semantic_analysis/ast_node/declaration/impl_trait.rs

@@ -44,7 +44,7 @@ impl ty::TyImplTrait {
         // Type check the type parameters. This will also insert them into the
         // current namespace.
         let new_impl_type_parameters = check!(
-            TypeParameter::type_check_type_params(ctx.by_ref(), impl_type_parameters, false),
+            TypeParameter::type_check_type_params(ctx.by_ref(), impl_type_parameters),
             return err(warnings, errors),
             warnings,
             errors
@@ -262,7 +262,7 @@ impl ty::TyImplTrait {
         // Type check the type parameters. This will also insert them into the
         // current namespace.
         let new_impl_type_parameters = check!(
-            TypeParameter::type_check_type_params(ctx.by_ref(), impl_type_parameters, false),
+            TypeParameter::type_check_type_params(ctx.by_ref(), impl_type_parameters),
             return err(warnings, errors),
             warnings,
             errors
@@ -300,9 +300,11 @@ impl ty::TyImplTrait {
         );
 
         check!(
-            implementing_for
-                .type_id
-                .check_type_parameter_bounds(&ctx, &implementing_for.span),
+            implementing_for.type_id.check_type_parameter_bounds(
+                &ctx,
+                &implementing_for.span,
+                vec![]
+            ),
             return err(warnings, errors),
             warnings,
             errors
@@ -421,6 +423,19 @@ fn type_check_trait_implementation(
         errors
     );
 
+    for (type_arg, type_param) in trait_type_arguments.iter().zip(trait_type_parameters) {
+        check!(
+            type_arg.type_id.check_type_parameter_bounds(
+                &ctx,
+                &type_arg.span(),
+                type_param.trait_constraints.clone()
+            ),
+            return err(warnings, errors),
+            warnings,
+            errors
+        );
+    }
+
     // This map keeps track of the remaining functions in the interface surface
     // that still need to be implemented for the trait to be fully implemented.
     let mut method_checklist: BTreeMap<Ident, ty::TyTraitFn> = BTreeMap::new();

sway-core/src/semantic_analysis/ast_node/declaration/struct.rs

@@ -30,7 +30,7 @@ impl ty::TyStructDecl {
         // Type check the type parameters. This will also insert them into the
         // current namespace.
         let new_type_parameters = check!(
-            TypeParameter::type_check_type_params(ctx.by_ref(), type_parameters, false),
+            TypeParameter::type_check_type_params(ctx.by_ref(), type_parameters),
             return err(warnings, errors),
             warnings,
             errors

sway-core/src/semantic_analysis/ast_node/declaration/trait.rs

@@ -56,7 +56,7 @@ impl ty::TyTraitDecl {
         // Type check the type parameters. This will also insert them into the
         // current namespace.
         let new_type_parameters = check!(
-            TypeParameter::type_check_type_params(ctx.by_ref(), type_parameters, true),
+            TypeParameter::type_check_type_params(ctx.by_ref(), type_parameters),
             return err(warnings, errors),
             warnings,
             errors

sway-core/src/semantic_analysis/ast_node/expression/typed_expression/enum_instantiation.rs

@@ -110,7 +110,7 @@ pub(crate) fn instantiate_enum(
             let type_id = type_engine.insert(engines, TypeInfo::Enum(enum_ref.clone()));
 
             check!(
-                type_id.check_type_parameter_bounds(&ctx, &enum_variant_name.span()),
+                type_id.check_type_parameter_bounds(&ctx, &enum_variant_name.span(), vec![]),
                 return err(warnings, errors),
                 warnings,
                 errors

sway-core/src/semantic_analysis/ast_node/expression/typed_expression/struct_instantiation.rs

@@ -131,7 +131,7 @@ pub(crate) fn struct_instantiation(
     }
 
     check!(
-        type_id.check_type_parameter_bounds(&ctx, &span),
+        type_id.check_type_parameter_bounds(&ctx, &span, vec![]),
         return err(warnings, errors),
         warnings,
         errors

sway-core/src/type_system/ast_elements/type_parameter.rs

@@ -134,20 +134,13 @@ impl TypeParameter {
     pub(crate) fn type_check_type_params(
         mut ctx: TypeCheckContext,
         type_params: Vec<TypeParameter>,
-        disallow_trait_constraints: bool,
     ) -> CompileResult<Vec<TypeParameter>> {
         let mut warnings = vec![];
         let mut errors = vec![];
 
         let mut new_type_params: Vec<TypeParameter> = vec![];
 
         for type_param in type_params.into_iter() {
-            if disallow_trait_constraints && !type_param.trait_constraints.is_empty() {
-                let errors = vec![CompileError::WhereClauseNotYetSupported {
-                    span: type_param.trait_constraints_span,
-                }];
-                return err(vec![], errors);
-            }
             new_type_params.push(check!(
                 TypeParameter::type_check(ctx.by_ref(), type_param),
                 continue,

sway-core/src/type_system/id.rs

@@ -363,16 +363,21 @@ impl TypeId {
         &self,
         ctx: &TypeCheckContext,
         span: &Span,
+        trait_constraints: Vec<TraitConstraint>,
     ) -> CompileResult<()> {
         let warnings = vec![];
         let mut errors = vec![];
         let engines = ctx.engines();
 
-        let structure_generics = engines
+        let mut structure_generics = engines
             .te()
             .get(*self)
             .extract_inner_types_with_trait_constraints(engines);
 
+        if !trait_constraints.is_empty() {
+            structure_generics.insert(*self, trait_constraints);
+        }
+
         for (structure_type_id, structure_trait_constraints) in &structure_generics {
             if structure_trait_constraints.is_empty() {
                 continue;

sway-error/src/error.rs

@@ -564,8 +564,6 @@ pub enum CompileError {
     Lex { error: LexError },
     #[error("{}", error)]
     Parse { error: ParseError },
-    #[error("\"where\" clauses are not yet supported")]
-    WhereClauseNotYetSupported { span: Span },
     #[error("Could not evaluate initializer to a const declaration.")]
     NonConstantDeclValue { span: Span },
     #[error("Declaring storage in a {program_kind} is not allowed.")]
@@ -787,7 +785,6 @@ impl Spanned for CompileError {
             UnexpectedDeclaration { span, .. } => span.clone(),
             ContractAddressMustBeKnown { span, .. } => span.clone(),
             ConvertParseTree { error } => error.span(),
-            WhereClauseNotYetSupported { span, .. } => span.clone(),
             Lex { error } => error.span(),
             Parse { error } => error.span.clone(),
             EnumNotFound { span, .. } => span.clone(),

test/src/e2e_vm_tests/test_programs/should_fail/where_clause_traits/Forc.lock

@@ -0,0 +1,8 @@
+[[package]]
+name = 'core'
+source = 'path+from-root-8E4C78460FB62C32'
+
+[[package]]
+name = 'where_clause_traits'
+source = 'member'
+dependencies = ['core']

test/src/e2e_vm_tests/test_programs/should_fail/where_clause_traits/Forc.toml

@@ -0,0 +1,9 @@
+[project]
+name = "where_clause_traits"
+authors = ["Fuel Labs <contact@fuel.sh>"]
+entry = "main.sw"
+license = "Apache-2.0"
+implicit-std = false
+
+[dependencies]
+core = { path = "../../../../../../sway-lib-core" }

test/src/e2e_vm_tests/test_programs/should_fail/where_clause_traits/src/main.sw

@@ -0,0 +1,26 @@
+script;
+
+trait MyTrait {
+    fn method(self);
+}
+
+trait MyTraitGeneric<T> where T : MyTrait {
+    fn method(self);
+}
+
+struct S1 {
+    s1: u64
+}
+
+impl MyTraitGeneric<S1> for u64 {
+    fn method(self){
+    }
+}
+
+impl<T> MyTraitGeneric<T> for u32 {
+    fn method(self){
+    }
+}
+
+fn main() {
+}

test/src/e2e_vm_tests/test_programs/should_fail/where_clause_traits/test.toml

@@ -0,0 +1,8 @@
+category = "fail"
+
+# check: $()impl MyTraitGeneric<S1> for u64 {
+# nextln:$()Trait "MyTrait" is not implemented for type "S1".
+
+# check: $()impl<T> MyTraitGeneric<T> for u32 {
+# nextln: $()Expects trait constraint "T: MyTrait" which is missing from type parameter "T".
+

test/src/e2e_vm_tests/test_programs/should_pass/language/where_clause_traits/Forc.lock

@@ -0,0 +1,13 @@
+[[package]]
+name = 'core'
+source = 'path+from-root-8E4C78460FB62C32'
+
+[[package]]
+name = 'std'
+source = 'path+from-root-8E4C78460FB62C32'
+dependencies = ['core']
+
+[[package]]
+name = 'where_clause_traits'
+source = 'member'
+dependencies = ['std']

test/src/e2e_vm_tests/test_programs/should_pass/language/where_clause_traits/Forc.toml

@@ -0,0 +1,8 @@
+[project]
+name = "where_clause_traits"
+authors = ["Fuel Labs <contact@fuel.sh>"]
+entry = "main.sw"
+license = "Apache-2.0"
+
+[dependencies]
+std = { path = "../../../../../../../sway-lib-std" }

test/src/e2e_vm_tests/test_programs/should_pass/language/where_clause_traits/json_abi_oracle.json

@@ -0,0 +1,25 @@
+{
+  "configurables": [],
+  "functions": [
+    {
+      "attributes": null,
+      "inputs": [],
+      "name": "main",
+      "output": {
+        "name": "",
+        "type": 0,
+        "typeArguments": null
+      }
+    }
+  ],
+  "loggedTypes": [],
+  "messagesTypes": [],
+  "types": [
+    {
+      "components": null,
+      "type": "u8",
+      "typeId": 0,
+      "typeParameters": null
+    }
+  ]
+}

test/src/e2e_vm_tests/test_programs/should_pass/language/where_clause_traits/src/main.sw

@@ -0,0 +1,31 @@
+script;
+
+trait MyTrait {
+    fn new() -> Self;
+}
+
+trait MyTraitGeneric<T> where T : MyTrait {
+    fn get_value(self) -> T;
+}
+
+struct S1 {
+    s1: u64
+}
+
+impl MyTrait for S1 {
+    fn new() -> Self {
+        S1 {s1: 0}
+    }
+}
+
+impl MyTraitGeneric<S1> for u64 {
+    fn get_value(self) -> S1 {
+        S1::new()
+    }
+}
+
+fn main() -> u8 {
+    let _s0: S1 = 42u64.get_value();
+
+    0u8
+}

test/src/e2e_vm_tests/test_programs/should_pass/language/where_clause_traits/test.toml

@@ -0,0 +1,5 @@
+category = "run"
+expected_result = { action = "return", value = 0 }
+validate_abi = true
+
+expected_warnings = 1