11 files changed, 280 insertions, 196 deletions

diff --git a/code/package.json b/code/package.json
index 00604efcc..282e533af 100644
--- a/code/package.json
+++ b/code/package.json
@@ -52,6 +52,10 @@
     ],
     "commands": [
       {
+        "command": "libsyntax-rust.createFile",
+        "title": "Show Rust syntax tree"
+      },
+      {
         "command": "libsyntax-rust.syntaxTree",
         "title": "Show Rust syntax tree"
       },
diff --git a/code/src/extension.ts b/code/src/extension.ts
index c25e8cb61..b9d009776 100644
--- a/code/src/extension.ts
+++ b/code/src/extension.ts
@@ -81,11 +81,21 @@ export function activate(context: vscode.ExtensionContext) {
         let e = await vscode.window.showTextDocument(doc)
         e.revealRange(range, vscode.TextEditorRevealType.InCenter)
     })
-    console.log("ping")
+
     registerCommand('libsyntax-rust.run', async (cmd: ProcessSpec) => {
         let task = createTask(cmd)
         await vscode.tasks.executeTask(task)
     })
+    registerCommand('libsyntax-rust.createFile', async (uri_: string) => {
+        console.log(`uri: ${uri_}`)
+        let uri = vscode.Uri.parse(uri_)
+        let edit = new vscode.WorkspaceEdit()
+        edit.createFile(uri)
+        await vscode.workspace.applyEdit(edit)
+        let doc = await vscode.workspace.openTextDocument(uri)
+        await vscode.window.showTextDocument(doc)
+        console.log("Done")
+    })
 
     dispose(vscode.workspace.registerTextDocumentContentProvider(
         'libsyntax-rust',
diff --git a/crates/libanalysis/src/lib.rs b/crates/libanalysis/src/lib.rs
index a3f721cc8..49c39e1f3 100644
--- a/crates/libanalysis/src/lib.rs
+++ b/crates/libanalysis/src/lib.rs
@@ -12,12 +12,9 @@ extern crate rayon;
 mod symbol_index;
 mod module_map;
 
-use once_cell::sync::OnceCell;
-use rayon::prelude::*;
-
 use std::{
     fmt,
-    path::{Path},
+    path::{Path, PathBuf},
     sync::{
         Arc,
         atomic::{AtomicBool, Ordering::SeqCst},
@@ -26,13 +23,16 @@ use std::{
     time::Instant,
 };
 
+use once_cell::sync::OnceCell;
+use rayon::prelude::*;
+
 use libsyntax2::{
     File,
     TextUnit, TextRange, SmolStr,
     ast::{self, AstNode, NameOwner},
     SyntaxKind::*,
 };
-use libeditor::{LineIndex, FileSymbol, find_node_at_offset};
+use libeditor::{Diagnostic, LineIndex, FileSymbol, find_node_at_offset};
 
 use self::{
     symbol_index::FileSymbols,
@@ -130,6 +130,9 @@ impl WorldState {
     }
 }
 
+pub enum QuickFix {
+    CreateFile(PathBuf),
+}
 
 impl World {
     pub fn file_syntax(&self, file_id: FileId) -> Result<File> {
@@ -210,6 +213,29 @@ impl World {
         Ok(vec![])
     }
 
+    pub fn diagnostics(&self, file_id: FileId) -> Result<Vec<(Diagnostic, Option<QuickFix>)>> {
+        let syntax = self.file_syntax(file_id)?;
+        let mut res = libeditor::diagnostics(&syntax)
+            .into_iter()
+            .map(|d| (d, None))
+            .collect::<Vec<_>>();
+        for module in syntax.ast().modules() {
+            if module.has_semi() && self.resolve_module(file_id, module).is_empty() {
+                if let Some(name) = module.name() {
+                    let d = Diagnostic {
+                        range: name.syntax().range(),
+                        msg: "unresolved module".to_string(),
+                    };
+                    let quick_fix = self.data.module_map.suggested_child_mod_path(module)
+                        .map(QuickFix::CreateFile);
+
+                    res.push((d, quick_fix))
+                }
+            }
+        }
+        Ok(res)
+    }
+
     fn index_resolve(&self, name_ref: ast::NameRef) -> Vec<(FileId, FileSymbol)> {
         let name = name_ref.text();
         let mut query = Query::new(name.to_string());
diff --git a/crates/libanalysis/src/module_map.rs b/crates/libanalysis/src/module_map.rs
index 6a9104d84..4f480591e 100644
--- a/crates/libanalysis/src/module_map.rs
+++ b/crates/libanalysis/src/module_map.rs
@@ -93,6 +93,11 @@ impl ModuleMap {
         res
     }
 
+    pub fn suggested_child_mod_path(&self, m: ast::Module) -> Option<PathBuf> {
+        let name = m.name()?;
+        Some(PathBuf::from(format!("../{}.rs", name.text())))
+    }
+
     fn links(
         &self,
         file_resolver: &FileResolver,
diff --git a/crates/libanalysis/tests/tests.rs b/crates/libanalysis/tests/tests.rs
index 32abf9152..b3c357b02 100644
--- a/crates/libanalysis/tests/tests.rs
+++ b/crates/libanalysis/tests/tests.rs
@@ -45,6 +45,19 @@ fn test_resolve_module() {
 }
 
 #[test]
+fn test_unresolved_module_diagnostic() {
+    let mut world = WorldState::new();
+    world.change_file(FileId(1), Some("mod foo;".to_string()));
+
+    let snap = world.snapshot(|_id, _path| None);
+    let diagnostics = snap.diagnostics(FileId(1)).unwrap();
+    assert_eq_dbg(
+        r#"[Diagnostic { range: [4; 7), msg: "unresolved module" }]"#,
+        &diagnostics,
+    );
+}
+
+#[test]
 fn test_resolve_parent_module() {
     let mut world = WorldState::new();
     world.change_file(FileId(1), Some("mod foo;".to_string()));
diff --git a/crates/libeditor/scope.rs b/crates/libeditor/scope.rs
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/crates/libeditor/scope.rs
diff --git a/crates/libeditor/src/completion.rs b/crates/libeditor/src/completion.rs
index 69c039e83..242a3a434 100644
--- a/crates/libeditor/src/completion.rs
+++ b/crates/libeditor/src/completion.rs
@@ -1,20 +1,14 @@
-use std::{
-    fmt,
-    collections::HashMap,
-};
-
 use libsyntax2::{
-    File, TextUnit, AstNode, SyntaxNodeRef, SyntaxNode, SmolStr,
-    ast::{self, NameOwner},
+    File, TextUnit, AstNode,
+    ast::self,
     algo::{
         ancestors,
-        walk::preorder,
-        generate,
     },
 };
 
 use {
     AtomEdit, find_node_at_offset,
+    scope::{FnScopes, compute_scopes},
 };
 
 #[derive(Debug)]
@@ -43,178 +37,3 @@ fn complete(name_ref: ast::NameRef, scopes: &FnScopes) -> Vec<CompletionItem> {
         })
         .collect()
 }
-
-fn compute_scopes(fn_def: ast::FnDef) -> FnScopes {
-    let mut scopes = FnScopes::new();
-    let root = scopes.root_scope();
-    fn_def.param_list().into_iter()
-        .flat_map(|it| it.params())
-        .filter_map(|it| it.pat())
-        .for_each(|it| scopes.add_bindings(root, it));
-
-    if let Some(body) = fn_def.body() {
-        compute_block_scopes(body, &mut scopes, root)
-    }
-    scopes
-}
-
-fn compute_block_scopes(block: ast::Block, scopes: &mut FnScopes, mut scope: ScopeId) {
-    for stmt in block.statements() {
-        match stmt {
-            ast::Stmt::LetStmt(stmt) => {
-                scope = scopes.new_scope(scope);
-                if let Some(pat) = stmt.pat() {
-                    scopes.add_bindings(scope, pat);
-                }
-                if let Some(expr) = stmt.initializer() {
-                    scopes.set_scope(expr.syntax(), scope)
-                }
-            }
-            ast::Stmt::ExprStmt(expr_stmt) => {
-                if let Some(expr) = expr_stmt.expr() {
-                    scopes.set_scope(expr.syntax(), scope);
-                    compute_expr_scopes(expr, scopes, scope);
-                }
-            }
-        }
-    }
-    if let Some(expr) = block.expr() {
-        scopes.set_scope(expr.syntax(), scope);
-        compute_expr_scopes(expr, scopes, scope);
-    }
-}
-
-fn compute_expr_scopes(expr: ast::Expr, scopes: &mut FnScopes, scope: ScopeId) {
-    match expr {
-        ast::Expr::IfExpr(e) => {
-            let cond_scope = e.condition().and_then(|cond| {
-                compute_cond_scopes(cond, scopes, scope)
-            });
-            if let Some(block) = e.then_branch() {
-                compute_block_scopes(block, scopes, cond_scope.unwrap_or(scope));
-            }
-            if let Some(block) = e.else_branch() {
-                compute_block_scopes(block, scopes, scope);
-            }
-        },
-        ast::Expr::WhileExpr(e) => {
-            let cond_scope = e.condition().and_then(|cond| {
-                compute_cond_scopes(cond, scopes, scope)
-            });
-            if let Some(block) = e.body() {
-                compute_block_scopes(block, scopes, cond_scope.unwrap_or(scope));
-            }
-        },
-        ast::Expr::BlockExpr(e) => {
-            if let Some(block) = e.block() {
-                compute_block_scopes(block, scopes, scope);
-            }
-        }
-        // ForExpr(e) => TODO,
-        _ => {
-            expr.syntax().children()
-                .filter_map(ast::Expr::cast)
-                .for_each(|expr| compute_expr_scopes(expr, scopes, scope))
-        }
-    };
-
-    fn compute_cond_scopes(cond: ast::Condition, scopes: &mut FnScopes, scope: ScopeId) -> Option<ScopeId> {
-        if let Some(expr) = cond.expr() {
-            compute_expr_scopes(expr, scopes, scope);
-        }
-        if let Some(pat) = cond.pat() {
-            let s = scopes.new_scope(scope);
-            scopes.add_bindings(s, pat);
-            Some(s)
-        } else {
-            None
-        }
-    }
-}
-
-type ScopeId = usize;
-
-#[derive(Debug)]
-struct FnScopes {
-    scopes: Vec<ScopeData>,
-    scope_for: HashMap<SyntaxNode, ScopeId>,
-}
-
-impl FnScopes {
-    fn new() -> FnScopes {
-        FnScopes {
-            scopes: vec![],
-            scope_for: HashMap::new(),
-        }
-    }
-    fn root_scope(&mut self) -> ScopeId {
-        let res = self.scopes.len();
-        self.scopes.push(ScopeData { parent: None, entries: vec![] });
-        res
-    }
-    fn new_scope(&mut self, parent: ScopeId) -> ScopeId {
-        let res = self.scopes.len();
-        self.scopes.push(ScopeData { parent: Some(parent), entries: vec![] });
-        res
-    }
-    fn add_bindings(&mut self, scope: ScopeId, pat: ast::Pat) {
-        let entries = preorder(pat.syntax())
-            .filter_map(ast::BindPat::cast)
-            .filter_map(ScopeEntry::new);
-        self.scopes[scope].entries.extend(entries);
-    }
-    fn set_scope(&mut self, node: SyntaxNodeRef, scope: ScopeId) {
-        self.scope_for.insert(node.owned(), scope);
-    }
-    fn entries(&self, scope: ScopeId) -> &[ScopeEntry] {
-        &self.scopes[scope].entries
-    }
-    fn scope_for(&self, node: SyntaxNodeRef) -> Option<ScopeId> {
-        ancestors(node)
-            .filter_map(|it| self.scope_for.get(&it.owned()).map(|&scope| scope))
-            .next()
-    }
-    fn scope_chain<'a>(&'a self, node: SyntaxNodeRef) -> impl Iterator<Item=ScopeId> + 'a {
-        generate(self.scope_for(node), move |&scope| self.scopes[scope].parent)
-    }
-}
-
-#[derive(Debug)]
-struct ScopeData {
-    parent: Option<ScopeId>,
-    entries: Vec<ScopeEntry>
-}
-
-struct ScopeEntry {
-    syntax: SyntaxNode
-}
-
-impl ScopeEntry {
-    fn new(pat: ast::BindPat) -> Option<ScopeEntry> {
-        if pat.name().is_some() {
-            Some(ScopeEntry { syntax: pat.syntax().owned() })
-        } else {
-            None
-        }
-    }
-
-    fn name(&self) -> SmolStr {
-        self.ast().name()
-            .unwrap()
-            .text()
-    }
-
-    fn ast(&self) -> ast::BindPat {
-        ast::BindPat::cast(self.syntax.borrowed())
-            .unwrap()
-    }
-}
-
-impl fmt::Debug for ScopeEntry {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.debug_struct("ScopeEntry")
-         .field("name", &self.name())
-         .field("syntax", &self.syntax)
-         .finish()
-    }
-}
diff --git a/crates/libeditor/src/lib.rs b/crates/libeditor/src/lib.rs
index 60489f7e3..d39e56d81 100644
--- a/crates/libeditor/src/lib.rs
+++ b/crates/libeditor/src/lib.rs
@@ -9,6 +9,7 @@ mod edit;
 mod code_actions;
 mod typing;
 mod completion;
+mod scope;
 
 use libsyntax2::{
     File, TextUnit, TextRange, SyntaxNodeRef,
diff --git a/crates/libeditor/src/scope.rs b/crates/libeditor/src/scope.rs
new file mode 100644
index 000000000..1fec0b24e
--- /dev/null
+++ b/crates/libeditor/src/scope.rs
@@ -0,0 +1,183 @@
+use std::{
+    fmt,
+    collections::HashMap,
+};
+
+use libsyntax2::{
+    SyntaxNodeRef, SyntaxNode, SmolStr, AstNode,
+    ast::{self, NameOwner},
+    algo::{ancestors, generate, walk::preorder}
+};
+
+pub fn compute_scopes(fn_def: ast::FnDef) -> FnScopes {
+    let mut scopes = FnScopes::new();
+    let root = scopes.root_scope();
+    fn_def.param_list().into_iter()
+        .flat_map(|it| it.params())
+        .filter_map(|it| it.pat())
+        .for_each(|it| scopes.add_bindings(root, it));
+
+    if let Some(body) = fn_def.body() {
+        compute_block_scopes(body, &mut scopes, root)
+    }
+    scopes
+}
+
+fn compute_block_scopes(block: ast::Block, scopes: &mut FnScopes, mut scope: ScopeId) {
+    for stmt in block.statements() {
+        match stmt {
+            ast::Stmt::LetStmt(stmt) => {
+                scope = scopes.new_scope(scope);
+                if let Some(pat) = stmt.pat() {
+                    scopes.add_bindings(scope, pat);
+                }
+                if let Some(expr) = stmt.initializer() {
+                    scopes.set_scope(expr.syntax(), scope)
+                }
+            }
+            ast::Stmt::ExprStmt(expr_stmt) => {
+                if let Some(expr) = expr_stmt.expr() {
+                    scopes.set_scope(expr.syntax(), scope);
+                    compute_expr_scopes(expr, scopes, scope);
+                }
+            }
+        }
+    }
+    if let Some(expr) = block.expr() {
+        scopes.set_scope(expr.syntax(), scope);
+        compute_expr_scopes(expr, scopes, scope);
+    }
+}
+
+fn compute_expr_scopes(expr: ast::Expr, scopes: &mut FnScopes, scope: ScopeId) {
+    match expr {
+        ast::Expr::IfExpr(e) => {
+            let cond_scope = e.condition().and_then(|cond| {
+                compute_cond_scopes(cond, scopes, scope)
+            });
+            if let Some(block) = e.then_branch() {
+                compute_block_scopes(block, scopes, cond_scope.unwrap_or(scope));
+            }
+            if let Some(block) = e.else_branch() {
+                compute_block_scopes(block, scopes, scope);
+            }
+        },
+        ast::Expr::WhileExpr(e) => {
+            let cond_scope = e.condition().and_then(|cond| {
+                compute_cond_scopes(cond, scopes, scope)
+            });
+            if let Some(block) = e.body() {
+                compute_block_scopes(block, scopes, cond_scope.unwrap_or(scope));
+            }
+        },
+        ast::Expr::BlockExpr(e) => {
+            if let Some(block) = e.block() {
+                compute_block_scopes(block, scopes, scope);
+            }
+        }
+        // ForExpr(e) => TODO,
+        _ => {
+            expr.syntax().children()
+                .filter_map(ast::Expr::cast)
+                .for_each(|expr| compute_expr_scopes(expr, scopes, scope))
+        }
+    };
+
+    fn compute_cond_scopes(cond: ast::Condition, scopes: &mut FnScopes, scope: ScopeId) -> Option<ScopeId> {
+        if let Some(expr) = cond.expr() {
+            compute_expr_scopes(expr, scopes, scope);
+        }
+        if let Some(pat) = cond.pat() {
+            let s = scopes.new_scope(scope);
+            scopes.add_bindings(s, pat);
+            Some(s)
+        } else {
+            None
+        }
+    }
+}
+
+type ScopeId = usize;
+
+#[derive(Debug)]
+pub struct FnScopes {
+    scopes: Vec<ScopeData>,
+    scope_for: HashMap<SyntaxNode, ScopeId>,
+}
+
+impl FnScopes {
+    fn new() -> FnScopes {
+        FnScopes {
+            scopes: vec![],
+            scope_for: HashMap::new(),
+        }
+    }
+    pub fn entries(&self, scope: ScopeId) -> &[ScopeEntry] {
+        &self.scopes[scope].entries
+    }
+    pub fn scope_chain<'a>(&'a self, node: SyntaxNodeRef) -> impl Iterator<Item=ScopeId> + 'a {
+        generate(self.scope_for(node), move |&scope| self.scopes[scope].parent)
+    }
+    fn root_scope(&mut self) -> ScopeId {
+        let res = self.scopes.len();
+        self.scopes.push(ScopeData { parent: None, entries: vec![] });
+        res
+    }
+    fn new_scope(&mut self, parent: ScopeId) -> ScopeId {
+        let res = self.scopes.len();
+        self.scopes.push(ScopeData { parent: Some(parent), entries: vec![] });
+        res
+    }
+    fn add_bindings(&mut self, scope: ScopeId, pat: ast::Pat) {
+        let entries = preorder(pat.syntax())
+            .filter_map(ast::BindPat::cast)
+            .filter_map(ScopeEntry::new);
+        self.scopes[scope].entries.extend(entries);
+    }
+    fn set_scope(&mut self, node: SyntaxNodeRef, scope: ScopeId) {
+        self.scope_for.insert(node.owned(), scope);
+    }
+    fn scope_for(&self, node: SyntaxNodeRef) -> Option<ScopeId> {
+        ancestors(node)
+            .filter_map(|it| self.scope_for.get(&it.owned()).map(|&scope| scope))
+            .next()
+    }
+}
+
+#[derive(Debug)]
+struct ScopeData {
+    parent: Option<ScopeId>,
+    entries: Vec<ScopeEntry>
+}
+
+pub struct ScopeEntry {
+    syntax: SyntaxNode
+}
+
+impl ScopeEntry {
+    fn new(pat: ast::BindPat) -> Option<ScopeEntry> {
+        if pat.name().is_some() {
+            Some(ScopeEntry { syntax: pat.syntax().owned() })
+        } else {
+            None
+        }
+    }
+    pub fn name(&self) -> SmolStr {
+        self.ast().name()
+            .unwrap()
+            .text()
+    }
+    fn ast(&self) -> ast::BindPat {
+        ast::BindPat::cast(self.syntax.borrowed())
+            .unwrap()
+    }
+}
+
+impl fmt::Debug for ScopeEntry {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("ScopeEntry")
+         .field("name", &self.name())
+         .field("syntax", &self.syntax)
+         .finish()
+    }
+}
diff --git a/crates/libsyntax2/src/grammar/expressions/atom.rs b/crates/libsyntax2/src/grammar/expressions/atom.rs
index bb5402af7..e83c82c92 100644
--- a/crates/libsyntax2/src/grammar/expressions/atom.rs
+++ b/crates/libsyntax2/src/grammar/expressions/atom.rs
@@ -29,8 +29,8 @@ pub(crate) fn literal(p: &mut Parser) -> Option<CompletedMarker> {
 pub(super) const ATOM_EXPR_FIRST: TokenSet =
     token_set_union![
         LITERAL_FIRST,
-        token_set![L_PAREN, PIPE, MOVE_KW, IF_KW, WHILE_KW, MATCH_KW, UNSAFE_KW, L_CURLY, RETURN_KW,
-                   IDENT, SELF_KW, SUPER_KW, COLONCOLON, BREAK_KW, CONTINUE_KW, LIFETIME ],
+        token_set![L_CURLY, L_PAREN, L_BRACK, PIPE, MOVE_KW, IF_KW, WHILE_KW, MATCH_KW, UNSAFE_KW,
+                   RETURN_KW, IDENT, SELF_KW, SUPER_KW, COLONCOLON, BREAK_KW, CONTINUE_KW, LIFETIME ],
     ];
 
 pub(super) fn atom_expr(p: &mut Parser, r: Restrictions) -> Option<CompletedMarker> {
diff --git a/crates/server/src/main_loop/handlers.rs b/crates/server/src/main_loop/handlers.rs
index e7ac53028..350eda7df 100644
--- a/crates/server/src/main_loop/handlers.rs
+++ b/crates/server/src/main_loop/handlers.rs
@@ -7,7 +7,7 @@ use languageserver_types::{
     CompletionItem,
 };
 use serde_json::{to_value, from_value};
-use libanalysis::{Query};
+use libanalysis::{Query, QuickFix};
 use libeditor;
 use libsyntax2::{
     TextUnit,
@@ -177,6 +177,30 @@ pub fn handle_code_action(
         };
         res.push(cmd);
     }
+
+    for (diag, quick_fix) in world.analysis().diagnostics(file_id)? {
+        let quick_fix = match quick_fix {
+            Some(quick_fix) => quick_fix,
+            None => continue,
+        };
+        if !contains_offset_nonstrict(diag.range, offset) {
+            continue;
+        }
+        let cmd = match quick_fix {
+            QuickFix::CreateFile(path) => {
+                let path = &path.to_str().unwrap()[3..]; // strip `../` b/c url is weird
+                let uri = params.text_document.uri.join(path)
+                    .unwrap();
+                let uri = ::url_serde::Ser::new(&uri);
+                Command {
+                    title: "Create file".to_string(),
+                    command: "libsyntax-rust.createFile".to_string(),
+                    arguments: Some(vec![to_value(uri).unwrap()]),
+                }
+            }
+        };
+        res.push(cmd)
+    }
     return Ok(Some(res));
 }
 
@@ -355,11 +379,10 @@ pub fn publish_diagnostics(
     uri: Url
 ) -> Result<req::PublishDiagnosticsParams> {
     let file_id = world.uri_to_file_id(&uri)?;
-    let file = world.analysis().file_syntax(file_id)?;
     let line_index = world.analysis().file_line_index(file_id)?;
-    let diagnostics = libeditor::diagnostics(&file)
+    let diagnostics = world.analysis().diagnostics(file_id)?
         .into_iter()
-        .map(|d| Diagnostic {
+        .map(|(d, _quick_fix)| Diagnostic {
             range: d.range.conv_with(&line_index),
             severity: Some(DiagnosticSeverity::Error),
             code: None,