feat(lsp): add goto definition for functions (#3656)

# Description

## Problem\*

Resolves <!-- Link to GitHub Issue -->
feat: goto definition - function #3657

## Summary\*

LSP server now understands goto definition command issued by Client (ie.
vscode). In case of function it will jump to it's definition.

## Additional Context

## Documentation\*

Check one:
- [x] No documentation needed.
- [ ] Documentation included in this PR.
- [ ] **[Exceptional Case]** Documentation to be submitted in a separate
PR.

# PR Checklist\*

- [x] I have tested the changes locally.
- [x] I have formatted the changes with [Prettier](https://prettier.io/)
and/or `cargo fmt` on default settings.

---------

Co-authored-by: kevaundray <kevtheappdev@gmail.com>

compiler/fm/src/file_map.rs

@@ -1,11 +1,12 @@
 use codespan_reporting::files::{Error, Files, SimpleFile, SimpleFiles};
 use serde::{Deserialize, Serialize};
+use std::collections::HashMap;
 use std::{ops::Range, path::PathBuf};
 
 // XXX: File and FileMap serve as opaque types, so that the rest of the library does not need to import the dependency
 // or worry about when we change the dep
 
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, Eq, Hash, PartialEq)]
 pub struct PathString(PathBuf);
 
 impl std::fmt::Display for PathString {
@@ -30,7 +31,10 @@ impl From<&PathBuf> for PathString {
     }
 }
 #[derive(Debug)]
-pub struct FileMap(SimpleFiles<PathString, String>);
+pub struct FileMap {
+    files: SimpleFiles<PathString, String>,
+    name_to_id: HashMap<PathString, FileId>,
+}
 
 // XXX: Note that we derive Default here due to ModuleOrigin requiring us to set a FileId
 #[derive(
@@ -59,17 +63,22 @@ impl<'input> File<'input> {
 
 impl FileMap {
     pub fn add_file(&mut self, file_name: PathString, code: String) -> FileId {
-        let file_id = self.0.add(file_name, code);
-        FileId(file_id)
+        let file_id = FileId(self.files.add(file_name.clone(), code));
+        self.name_to_id.insert(file_name, file_id);
+        file_id
     }
+
     pub fn get_file(&self, file_id: FileId) -> Option<File> {
-        self.0.get(file_id.0).map(File).ok()
+        self.files.get(file_id.0).map(File).ok()
     }
-}
 
+    pub fn get_file_id(&self, file_name: &PathString) -> Option<FileId> {
+        self.name_to_id.get(file_name).cloned()
+    }
+}
 impl Default for FileMap {
     fn default() -> Self {
-        FileMap(SimpleFiles::new())
+        FileMap { files: SimpleFiles::new(), name_to_id: HashMap::new() }
     }
 }
 
@@ -79,18 +88,18 @@ impl<'a> Files<'a> for FileMap {
     type Source = &'a str;
 
     fn name(&self, file_id: Self::FileId) -> Result<Self::Name, Error> {
-        Ok(self.0.get(file_id.as_usize())?.name().clone())
+        Ok(self.files.get(file_id.as_usize())?.name().clone())
     }
 
     fn source(&'a self, file_id: Self::FileId) -> Result<Self::Source, Error> {
-        Ok(self.0.get(file_id.as_usize())?.source().as_ref())
+        Ok(self.files.get(file_id.as_usize())?.source().as_ref())
     }
 
     fn line_index(&self, file_id: Self::FileId, byte_index: usize) -> Result<usize, Error> {
-        self.0.get(file_id.as_usize())?.line_index((), byte_index)
+        self.files.get(file_id.as_usize())?.line_index((), byte_index)
     }
 
     fn line_range(&self, file_id: Self::FileId, line_index: usize) -> Result<Range<usize>, Error> {
-        self.0.get(file_id.as_usize())?.line_range((), line_index)
+        self.files.get(file_id.as_usize())?.line_range((), line_index)
     }
 }

compiler/fm/src/lib.rs

@@ -109,6 +109,10 @@ impl FileManager {
 
         self.add_file(&candidate).ok_or_else(|| candidate.as_os_str().to_string_lossy().to_string())
     }
+
+    pub fn name_to_id(&self, file_name: PathBuf) -> Option<FileId> {
+        self.file_map.get_file_id(&PathString::from_path(file_name))
+    }
 }
 
 /// Returns true if a module's child module's are expected to be in the same directory.

compiler/noirc_errors/src/position.rs

@@ -85,6 +85,16 @@ impl Span {
     pub fn end(&self) -> u32 {
         self.0.end().into()
     }
+
+    pub fn contains(&self, other: &Span) -> bool {
+        self.start() <= other.start() && self.end() >= other.end()
+    }
+
+    pub fn is_smaller(&self, other: &Span) -> bool {
+        let self_distance = self.end() - self.start();
+        let other_distance = other.end() - other.start();
+        self_distance < other_distance
+    }
 }
 
 impl From<Span> for Range<usize> {
@@ -133,4 +143,8 @@ impl Location {
     pub fn dummy() -> Self {
         Self { span: Span::single_char(0), file: FileId::dummy() }
     }
+
+    pub fn contains(&self, other: &Location) -> bool {
+        self.file == other.file && self.span.contains(&other.span)
+    }
 }

compiler/noirc_frontend/src/hir/def_map/mod.rs

@@ -173,7 +173,6 @@ impl CrateDefMap {
             })
         })
     }
-
     /// Go through all modules in this crate, find all `contract ... { ... }` declarations,
     /// and collect them all into a Vec.
     pub fn get_all_contracts(&self, interner: &NodeInterner) -> Vec<Contract> {

compiler/noirc_frontend/src/hir/mod.rs

@@ -180,6 +180,14 @@ impl Context {
             .collect()
     }
 
+    /// Returns the [Location] of the definition of the given Ident found at [Span] of the given [FileId].
+    /// Returns [None] when definition is not found.
+    pub fn get_definition_location_from(&self, location: Location) -> Option<Location> {
+        let interner = &self.def_interner;
+
+        interner.find_location_index(location).and_then(|index| interner.resolve_location(index))
+    }
+
     /// Return a Vec of all `contract` declarations in the source code and the functions they contain
     pub fn get_all_contracts(&self, crate_id: &CrateId) -> Vec<Contract> {
         self.def_map(crate_id)

compiler/noirc_frontend/src/hir_def/traits.rs

@@ -60,7 +60,7 @@ pub struct Trait {
     pub self_type_typevar_id: TypeVariableId,
     pub self_type_typevar: TypeVariable,
 }
-
+#[derive(Debug)]
 pub struct TraitImpl {
     pub ident: Ident,
     pub typ: Type,

compiler/noirc_frontend/src/node_interner.rs

@@ -9,6 +9,7 @@ use crate::ast::Ident;
 use crate::graph::CrateId;
 use crate::hir::def_collector::dc_crate::{UnresolvedStruct, UnresolvedTrait, UnresolvedTypeAlias};
 use crate::hir::def_map::{LocalModuleId, ModuleId};
+
 use crate::hir_def::stmt::HirLetStatement;
 use crate::hir_def::traits::TraitImpl;
 use crate::hir_def::traits::{Trait, TraitConstraint};
@@ -36,6 +37,7 @@ type StructAttributes = Vec<SecondaryAttribute>;
 /// each definition or struct, etc. Because it is used on the Hir, the NodeInterner is
 /// useful in passes where the Hir is used - name resolution, type checking, and
 /// monomorphization - and it is not useful afterward.
+#[derive(Debug)]
 pub struct NodeInterner {
     nodes: Arena<Node>,
     func_meta: HashMap<FuncId, FuncMeta>,
@@ -156,7 +158,7 @@ pub enum TraitImplKind {
 ///
 /// Additionally, types can define specialized impls with methods of the same name
 /// as long as these specialized impls do not overlap. E.g. `impl Struct<u32>` and `impl Struct<u64>`
-#[derive(Default)]
+#[derive(Default, Debug)]
 pub struct Methods {
     direct: Vec<FuncId>,
     trait_impl_methods: Vec<FuncId>,
@@ -165,6 +167,7 @@ pub struct Methods {
 /// All the information from a function that is filled out during definition collection rather than
 /// name resolution. As a result, if information about a function is needed during name resolution,
 /// this is the only place where it is safe to retrieve it (where all fields are guaranteed to be initialized).
+#[derive(Debug, Clone)]
 pub struct FunctionModifiers {
     pub name: String,
 
@@ -451,6 +454,30 @@ impl NodeInterner {
         self.id_to_location.insert(expr_id.into(), Location::new(span, file));
     }
 
+    /// Scans the interner for the item which is located at that [Location]
+    ///
+    /// The [Location] may not necessarily point to the beginning of the item
+    /// so we check if the location's span is contained within the start or end
+    /// of each items [Span]
+    pub fn find_location_index(&self, location: Location) -> Option<impl Into<Index>> {
+        let mut location_candidate: Option<(&Index, &Location)> = None;
+
+        // Note: we can modify this in the future to not do a linear
+        // scan by storing a separate map of the spans or by sorting the locations.
+        for (index, interned_location) in self.id_to_location.iter() {
+            if interned_location.contains(&location) {
+                if let Some(current_location) = location_candidate {
+                    if interned_location.span.is_smaller(&current_location.1.span) {
+                        location_candidate = Some((index, interned_location));
+                    }
+                } else {
+                    location_candidate = Some((index, interned_location));
+                }
+            }
+        }
+        location_candidate.map(|(index, _location)| *index)
+    }
+
     /// Interns a HIR Function.
     pub fn push_fn(&mut self, func: HirFunction) -> FuncId {
         FuncId(self.nodes.insert(Node::Function(func)))
@@ -1190,6 +1217,37 @@ impl NodeInterner {
     pub fn get_selected_impl_for_ident(&self, ident_id: ExprId) -> Option<TraitImplKind> {
         self.selected_trait_implementations.get(&ident_id).cloned()
     }
+
+    /// For a given [Index] we return [Location] to which we resolved to
+    /// We currently return None for features not yet implemented
+    /// TODO(#3659): LSP goto def should error when Ident at Location could not resolve
+    pub(crate) fn resolve_location(&self, index: impl Into<Index>) -> Option<Location> {
+        let node = self.nodes.get(index.into())?;
+
+        match node {
+            Node::Function(func) => self.resolve_location(func.as_expr()),
+            Node::Expression(expression) => self.resolve_expression_location(expression),
+            _ => None,
+        }
+    }
+
+    /// Resolves the [Location] of the definition for a given [HirExpression]
+    ///
+    /// Note: current the code returns None because some expressions are not yet implemented.
+    fn resolve_expression_location(&self, expression: &HirExpression) -> Option<Location> {
+        match expression {
+            HirExpression::Ident(ident) => {
+                let definition_info = self.definition(ident.id);
+                match definition_info.kind {
+                    DefinitionKind::Function(func_id) => {
+                        Some(self.function_meta(&func_id).location)
+                    }
+                    _ => None,
+                }
+            }
+            _ => None,
+        }
+    }
 }
 
 impl Methods {
@@ -1242,7 +1300,7 @@ impl Methods {
 }
 
 /// These are the primitive type variants that we support adding methods to
-#[derive(Copy, Clone, Hash, PartialEq, Eq)]
+#[derive(Copy, Clone, Hash, PartialEq, Eq, Debug)]
 enum TypeMethodKey {
     /// Fields and integers share methods for ease of use. These methods may still
     /// accept only fields or integers, it is just that their names may not clash.

tooling/lsp/src/lib.rs

@@ -27,8 +27,8 @@ use notifications::{
     on_did_open_text_document, on_did_save_text_document, on_exit, on_initialized,
 };
 use requests::{
-    on_code_lens_request, on_formatting, on_initialize, on_profile_run_request, on_shutdown,
-    on_test_run_request, on_tests_request,
+    on_code_lens_request, on_formatting, on_goto_definition_request, on_initialize,
+    on_profile_run_request, on_shutdown, on_test_run_request, on_tests_request,
 };
 use serde_json::Value as JsonValue;
 use tower::Service;
@@ -76,6 +76,7 @@ impl NargoLspService {
             .request::<request::NargoTests, _>(on_tests_request)
             .request::<request::NargoTestRun, _>(on_test_run_request)
             .request::<request::NargoProfileRun, _>(on_profile_run_request)
+            .request::<request::GotoDefinition, _>(on_goto_definition_request)
             .notification::<notification::Initialized>(on_initialized)
             .notification::<notification::DidChangeConfiguration>(on_did_change_configuration)
             .notification::<notification::DidOpenTextDocument>(on_did_open_text_document)