Fail on mismatch in method return types for ABIs and traits (FuelLabs…

…#3022)

Replace unification with equality for return types. Unification does not
make a distinction between some integer types.

ref FuelLabs#2397


*Edit*:
I think I need to check parameter types as well and if needed do them in
a separate PR to keep it simpler and reduce review times.

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

@@ -1,6 +1,5 @@
 use std::collections::{HashMap, HashSet};
 
-use sway_error::error::{CompileError, InterfaceName};
 use sway_types::{Ident, Span, Spanned};
 
 use crate::{
@@ -14,7 +13,7 @@ use crate::{
         insert_type, look_up_type_id, set_type_as_storage_only, to_typeinfo, unify_with_self,
         CopyTypes, TypeId, TypeMapping, TypeParameter,
     },
-    CompileResult, TyFunctionDeclaration, TypeInfo,
+    CompileError, CompileResult, TyFunctionDeclaration, TypeInfo,
 };
 
 use super::TyTraitFn;
@@ -493,6 +492,7 @@ fn type_check_trait_implementation(
     block_span: &Span,
     is_contract: bool,
 ) -> CompileResult<Vec<TyFunctionDeclaration>> {
+    use sway_error::error::InterfaceName;
     let interface_name = || -> InterfaceName {
         if is_contract {
             InterfaceName::Abi(trait_name.suffix.clone())
@@ -596,7 +596,8 @@ fn type_check_trait_implementation(
             );
             warnings.append(&mut new_warnings);
             if !new_errors.is_empty() {
-                errors.push(CompileError::MismatchedTypeInTrait {
+                errors.push(CompileError::MismatchedTypeInInterfaceSurface {
+                    interface_name: interface_name(),
                     span: fn_decl_param.type_span.clone(),
                     given: fn_decl_param_type.to_string(),
                     expected: fn_signature_param_type.to_string(),
@@ -625,18 +626,17 @@ fn type_check_trait_implementation(
             });
         }
 
-        // unify the return type of the function declaration
-        // with the return type of the function signature
-        let (mut new_warnings, new_errors) = unify_with_self(
-            fn_decl.return_type,
-            fn_signature.return_type,
-            ctx.self_type(),
-            &fn_decl.return_type_span,
-            ctx.help_text(),
-        );
-        warnings.append(&mut new_warnings);
-        if !new_errors.is_empty() {
-            errors.push(CompileError::MismatchedTypeInTrait {
+        // the return type of the function declaration must be the same
+        // as the return type of the function signature
+        let self_type = ctx.self_type();
+        use super::ReplaceSelfType;
+        let mut fn_decl_ret_type = fn_decl.return_type;
+        fn_decl_ret_type.replace_self_type(self_type);
+        let mut fn_sign_ret_type = fn_signature.return_type;
+        fn_sign_ret_type.replace_self_type(self_type);
+        if look_up_type_id(fn_decl_ret_type) != look_up_type_id(fn_sign_ret_type) {
+            errors.push(CompileError::MismatchedTypeInInterfaceSurface {
+                interface_name: interface_name(),
                 span: fn_decl.return_type_span.clone(),
                 expected: fn_signature.return_type.to_string(),
                 given: fn_decl.return_type.to_string(),

sway-error/src/error.rs

@@ -151,9 +151,10 @@ pub enum CompileError {
     #[error(
         "Expected: {expected} \n\
          found:    {given}. The definition of this function must \
-         match the one in the trait declaration."
+         match the one in the {interface_name} declaration."
     )]
-    MismatchedTypeInTrait {
+    MismatchedTypeInInterfaceSurface {
+        interface_name: InterfaceName,
         span: Span,
         given: String,
         expected: String,
@@ -694,7 +695,7 @@ impl Spanned for CompileError {
             AssociatedFunctionCalledAsMethod { span, .. } => span.clone(),
             TypeParameterNotInTypeScope { span, .. } => span.clone(),
             MultipleImmediates(span) => span.clone(),
-            MismatchedTypeInTrait { span, .. } => span.clone(),
+            MismatchedTypeInInterfaceSurface { span, .. } => span.clone(),
             NotATrait { span, .. } => span.clone(),
             UnknownTrait { span, .. } => span.clone(),
             FunctionNotAPartOfInterfaceSurface { span, .. } => span.clone(),

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

@@ -5,10 +5,19 @@ contract;
 
 abi MyContract {
     fn foo(x: u64) -> str[7];
+    fn bar() -> u32;
+    fn baz() -> u64;
 }
 
 impl MyContract for Contract {
     fn foo(s: str[7]) -> str[7] {
         s
     }
+
+    fn bar() -> u64 {
+        0
+    }
+
+    fn baz() { // No return type here
+    }
 }

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

@@ -2,4 +2,12 @@ category = "fail"
 
 # check: fn foo(s: str[7]) -> str[7] {
 # nextln: $()Expected: u64
-# nextln: $()found:    str[7]. The definition of this function must match the one in the trait declaration.
+# nextln: $()found:    str[7]. The definition of this function must match the one in the ABI "MyContract" declaration.
+
+# check: fn bar() -> u64 {
+# nextln: $()Expected: u32
+# nextln: $()found:    u64. The definition of this function must match the one in the ABI "MyContract" declaration.
+
+# check: fn baz() {
+# nextln: $()Expected: u64
+# nextln: $()found:    (). The definition of this function must match the one in the ABI "MyContract" declaration.

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

@@ -6,6 +6,8 @@ library test;
 trait Foo {
     fn foo(x: u64) -> str[7];
     fn bar(variable: u64) -> bool;
+    fn baz() -> u32;
+    fn quux() -> u64;
 }
 
 struct S {
@@ -20,4 +22,11 @@ impl Foo for S {
     fn bar(ref mut variable: u64) -> bool {
         true
     }
+
+    fn baz() -> u64 {
+        0
+    }
+
+    fn quux() { // no return type
+    }
 }

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

@@ -2,7 +2,15 @@ category = "fail"
 
 # check: fn foo(s: str[7]) -> str[7] {
 # nextln: $()Expected: u64
-# nextln: $()found:    str[7]. The definition of this function must match the one in the trait declaration.
+# nextln: $()found:    str[7]. The definition of this function must match the one in the trait "Foo" declaration.
 
 # check: fn bar(ref mut variable: u64) -> bool {
 # nextln: $()Parameter mutability mismatch between the trait function declaration and its implementation.
+
+# check: fn baz() -> u64 {
+# nextln: $()Expected: u32
+# nextln: $()found:    u64. The definition of this function must match the one in the trait "Foo" declaration.
+
+# check: fn quux() {
+# nextln: $()Expected: u64
+# nextln: $()found:    (). The definition of this function must match the one in the trait "Foo" declaration.