feat: implement method calls

crates/mun_codegen/src/ir/body.rs

@@ -234,6 +234,9 @@
                 self.gen_binary_op(expr, *lhs, *rhs, op.expect("missing op"))
             }
             Expr::UnaryOp { expr, op } => self.gen_unary_op(*expr, *op),
+            Expr::MethodCall { .. } => {
+                unimplemented!("Method calls are not yet implemented in the IR generator")
+            }
             Expr::Call {
                 ref callee,
                 ref args,

crates/mun_hir/src/code_model/function.rs

@@ -103,6 +103,21 @@ impl FunctionData {
     pub fn is_extern(&self) -> bool {
         self.flags.is_extern()
     }
+
+    /// Returns true if the first param is `self`. This is relevant to decide
+    /// whether this can be called as a method as opposed to an associated
+    /// function.
+    ///
+    /// An associated function is a function that is associated with a type but
+    /// doesn't "act" on an instance. E.g. in Rust terms you can call
+    /// `String::from("foo")` but you can't call `String::len()`.
+    ///
+    /// A method on the other hand is a function that is associated with a type
+    /// and does "act" on an instance. E.g. in Rust terms you can call
+    /// `foo.len()` but you can't call `foo.new()`.
+    pub fn has_self_param(&self) -> bool {
+        self.flags.has_self_param()
+    }
 }
 
 impl Function {

crates/mun_hir/src/code_model/struct.rs

@@ -244,6 +244,13 @@ impl StructData {
     pub fn type_ref_map(&self) -> &TypeRefMap {
         &self.type_ref_map
     }
+
+    /// Returns the index of the field with the specified name.
+    pub fn find_field(&self, name: &Name) -> Option<LocalFieldId> {
+        self.fields
+            .iter()
+            .find_map(|(idx, data)| (data.name == *name).then_some(idx))
+    }
 }
 
 impl HasVisibility for Struct {

crates/mun_hir/src/db.rs

@@ -2,16 +2,17 @@
 
 use std::sync::Arc;
 
+use la_arena::ArenaMap;
 use mun_db::Upcast;
 use mun_hir_input::{FileId, PackageId, SourceDatabase};
 use mun_syntax::{ast, Parse, SourceFile};
 use mun_target::{abi, spec::Target};
 
 use crate::{
-    code_model::{FunctionData, ImplData, StructData, TypeAliasData},
+    code_model::{r#struct::LocalFieldId, FunctionData, ImplData, StructData, TypeAliasData},
     expr::BodySourceMap,
     ids,
-    ids::{DefWithBodyId, FunctionId, ImplId},
+    ids::{DefWithBodyId, FunctionId, ImplId, VariantId},
     item_tree::{self, ItemTree},
     method_resolution::InherentImpls,
     name_resolution::Namespace,
@@ -67,6 +68,9 @@ pub trait DefDatabase: InternDatabase + AstDatabase + Upcast<dyn AstDatabase> {
     #[salsa::invoke(visibility::function_visibility_query)]
     fn function_visibility(&self, def: FunctionId) -> Visibility;
 
+    #[salsa::invoke(visibility::field_visibilities_query)]
+    fn field_visibilities(&self, variant_id: VariantId) -> Arc<ArenaMap<LocalFieldId, Visibility>>;
+
     /// Returns the `PackageDefs` for the specified `PackageId`. The
     /// `PackageDefs` contains all resolved items defined for every module
     /// in the package.

crates/mun_hir/src/diagnostics.rs

@@ -3,7 +3,9 @@
 use mun_hir_input::FileId;
 use mun_syntax::{ast, AstPtr, SmolStr, SyntaxNode, SyntaxNodePtr, TextRange};
 
-use crate::{code_model::StructKind, in_file::InFile, HirDatabase, IntTy, Name, Ty};
+use crate::{
+    code_model::StructKind, ids::FunctionId, in_file::InFile, HirDatabase, IntTy, Name, Ty,
+};
 
 /// Diagnostic defines `mun_hir` API for errors and warnings.
 ///
@@ -865,3 +867,49 @@
         self
     }
 }
+
+/// An error that is emitted if a method is called that is not visible from the
+/// current scope
+#[derive(Debug)]
+pub struct MethodNotInScope {
+    pub method_call: InFile<AstPtr<ast::MethodCallExpr>>,
+    pub receiver_ty: Ty,
+}
+
+impl Diagnostic for MethodNotInScope {
+    fn message(&self) -> String {
+        "method not in scope for type".to_string()
+    }
+
+    fn source(&self) -> InFile<SyntaxNodePtr> {
+        self.method_call.clone().map(Into::into)
+    }
+
+    fn as_any(&self) -> &(dyn Any + Send + 'static) {
+        self
+    }
+}
+
+/// An error that is emitted if an unknown method is called
+#[derive(Debug)]
+pub struct MethodNotFound {
+    pub method_call: InFile<AstPtr<ast::MethodCallExpr>>,
+    pub receiver_ty: Ty,
+    pub method_name: Name,
+    pub field_with_same_name: Option<Ty>,
+    pub associated_function_with_same_name: Option<FunctionId>,
+}
+
+impl Diagnostic for MethodNotFound {
+    fn message(&self) -> String {
+        format!("method `{}` does not exist", &self.method_name)
+    }
+
+    fn source(&self) -> InFile<SyntaxNodePtr> {
+        self.method_call.clone().map(Into::into)
+    }
+
+    fn as_any(&self) -> &(dyn Any + Send + 'static) {
+        self
+    }
+}

crates/mun_hir/src/expr.rs

@@ -285,6 +285,11 @@
         callee: ExprId,
         args: Vec<ExprId>,
     },
+    MethodCall {
+        receiver: ExprId,
+        method_name: Name,
+        args: Vec<ExprId>,
+    },
     Path(Path),
     If {
         condition: ExprId,
@@ -399,6 +404,12 @@
                     f(*arg);
                 }
             }
+            Expr::MethodCall { receiver, args, .. } => {
+                f(*receiver);
+                for arg in args {
+                    f(*arg);
+                }
+            }
             Expr::BinaryOp { lhs, rhs, .. } => {
                 f(*lhs);
                 f(*rhs);
@@ -877,6 +888,24 @@
                 };
                 self.alloc_expr(Expr::Call { callee, args }, syntax_ptr)
             }
+            ast::ExprKind::MethodCallExpr(e) => {
+                let receiver = self.collect_expr_opt(e.expr());
+                let args = e
+                    .arg_list()
+                    .into_iter()
+                    .flat_map(|arg_list| arg_list.args())
+                    .map(|e| self.collect_expr(e))
+                    .collect();
+                let method_name = e.name_ref().map_or_else(Name::missing, |nr| nr.as_name());
+                self.alloc_expr(
+                    Expr::MethodCall {
+                        receiver,
+                        method_name,
+                        args,
+                    },
+                    syntax_ptr,
+                )
+            }
             ast::ExprKind::ArrayExpr(e) => {
                 let exprs = e.exprs().map(|expr| self.collect_expr(expr)).collect();
                 self.alloc_expr(Expr::Array(exprs), syntax_ptr)

crates/mun_hir/src/expr/validator/uninitialized_access.rs

@@ -53,6 +53,12 @@
                     self.validate_expr_access(sink, initialized_patterns, *arg, expr_side);
                 }
             }
+            Expr::MethodCall { receiver, args, .. } => {
+                self.validate_expr_access(sink, initialized_patterns, *receiver, expr_side);
+                for arg in args.iter() {
+                    self.validate_expr_access(sink, initialized_patterns, *arg, expr_side);
+                }
+            }
             Expr::Path(p) => {
                 let resolver = resolver_for_expr(self.db.upcast(), self.body.owner(), expr);
                 self.validate_path_access(

crates/mun_hir/src/has_module.rs

@@ -3,7 +3,7 @@ use mun_hir_input::ModuleId;
 use crate::{
     ids::{
         AssocItemId, AssocItemLoc, FunctionId, ImplId, ItemContainerId, Lookup, StructId,
-        TypeAliasId,
+        TypeAliasId, VariantId,
     },
     item_tree::ItemTreeNode,
     DefDatabase,
@@ -60,3 +60,11 @@ impl HasModule for AssocItemId {
         }
     }
 }
+
+impl HasModule for VariantId {
+    fn module(&self, db: &dyn DefDatabase) -> ModuleId {
+        match self {
+            VariantId::StructId(it) => it.module(db),
+        }
+    }
+}

crates/mun_hir/src/ids.rs

@@ -200,3 +200,13 @@ impl From<FunctionId> for DefWithBodyId {
         DefWithBodyId::FunctionId(id)
     }
 }
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum VariantId {
+    StructId(StructId),
+}
+impl From<StructId> for VariantId {
+    fn from(value: StructId) -> Self {
+        VariantId::StructId(value)
+    }
+}

crates/mun_hir/src/method_resolution.rs

@@ -241,6 +241,9 @@
 
     /// Filter based on visibility from this module
     visible_from: Option<ModuleId>,
+
+    /// Whether to look up methods or associated functions.
+    association_mode: Option<AssociationMode>,
 }
 
 enum IsValidCandidate {
@@ -249,13 +252,41 @@
     NotVisible,
 }
 
+/// Whether to look up methods or associated functions.
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum AssociationMode {
+    /// Method call e.g. a method that takes self as the first argument.
+    WithSelf,
+
+    /// Associated function e.g. a method that does not take self as the first
+    /// argument.
+    WithoutSelf,
+}
+
 impl<'db> MethodResolutionCtx<'db> {
     pub fn new(db: &'db dyn HirDatabase, ty: Ty) -> Self {
         Self {
             db,
             ty,
             name: None,
             visible_from: None,
+            association_mode: None,
+        }
+    }
+
+    /// Filter methods based on the specified lookup mode.
+    pub fn with_association(self, association: AssociationMode) -> Self {
+        Self {
+            association_mode: Some(association),
+            ..self
+        }
+    }
+
+    /// Filter methods based on the specified lookup mode.
+    pub fn with_association_opt(self, association: Option<AssociationMode>) -> Self {
+        Self {
+            association_mode: association,
+            ..self
         }
     }
 
@@ -351,6 +382,16 @@
             }
         }
 
+        // Check the association mode
+        if let Some(association_mode) = self.association_mode {
+            if matches!(
+                (association_mode, data.has_self_param()),
+                (AssociationMode::WithSelf, false) | (AssociationMode::WithoutSelf, true)
+            ) {
+                return IsValidCandidate::No;
+            }
+        }
+
         // Check if the function is visible from the selected module
         if let Some(visible_from) = self.visible_from {
             if !self
@@ -376,9 +417,11 @@
     ty: &Ty,
     visible_from_module: ModuleId,
     name: &Name,
+    association_mode: Option<AssociationMode>,
 ) -> Result<FunctionId, Option<FunctionId>> {
     let mut not_visible = None;
     MethodResolutionCtx::new(db, ty.clone())
+        .with_association_opt(association_mode)
         .visible_from(visible_from_module)
         .with_name(name.clone())
         .collect(|item, visible| match item {
@@ -561,6 +604,7 @@
             &fixture.foo_ty,
             fixture.root_module.id,
             &Name::new("bar"),
+            None,
         )
         .is_ok());
     }
@@ -573,6 +617,7 @@
             &fixture.foo_ty,
             fixture.root_module.id,
             &Name::new("not_found"),
+            None,
         )
         .unwrap_err()
         .is_none());
@@ -586,6 +631,7 @@
             &fixture.foo_ty,
             fixture.root_module.id,
             &Name::new("baz"),
+            None,
         )
         .unwrap_err()
         .is_some());

crates/mun_hir/src/name.rs

@@ -69,6 +69,11 @@ impl Name {
             Repr::TupleField(_) => None,
         }
     }
+
+    /// Returns true if this name represents a missing name.
+    pub fn is_missing(&self) -> bool {
+        self == &Self::missing()
+    }
 }
 
 pub(crate) trait AsName {

crates/mun_hir/src/package_defs/tests.rs

@@ -184,7 +184,7 @@ fn use_() {
         r#"
     //- /bar.mun
     use package::Foo;
-    pub struct Bar(Foo);
+    pub struct Bar(pub Foo);
 
     //- /mod.mun
     pub use foo::Foo; // Re-export a child's definition