2 files changed, 80 insertions, 50 deletions

diff --git a/crates/syntax/src/ast/edit_in_place.rs b/crates/syntax/src/ast/edit_in_place.rs
index 04f97f368..168355555 100644
--- a/crates/syntax/src/ast/edit_in_place.rs
+++ b/crates/syntax/src/ast/edit_in_place.rs
@@ -195,18 +195,13 @@ impl ast::GenericParamList {
     pub fn add_generic_param(&self, generic_param: ast::GenericParam) {
         match self.generic_params().last() {
             Some(last_param) => {
-                let mut elems = Vec::new();
-                if !last_param
-                    .syntax()
-                    .siblings_with_tokens(Direction::Next)
-                    .any(|it| it.kind() == T![,])
-                {
-                    elems.push(make::token(T![,]).into());
-                    elems.push(make::tokens::single_space().into());
-                };
-                elems.push(generic_param.syntax().clone().into());
-                let after_last_param = Position::after(last_param.syntax());
-                ted::insert_all(after_last_param, elems);
+                let position = Position::after(last_param.syntax());
+                let elements = vec![
+                    make::token(T![,]).into(),
+                    make::tokens::single_space().into(),
+                    generic_param.syntax().clone().into(),
+                ];
+                ted::insert_all(position, elements);
             }
             None => {
                 let after_l_angle = Position::after(self.l_angle_token().unwrap());
diff --git a/crates/syntax/src/ast/make.rs b/crates/syntax/src/ast/make.rs
index 5a6687397..1998ad1f6 100644
--- a/crates/syntax/src/ast/make.rs
+++ b/crates/syntax/src/ast/make.rs
@@ -3,25 +3,55 @@
 //!
 //! Note that all functions here intended to be stupid constructors, which just
 //! assemble a finish node from immediate children. If you want to do something
-//! smarter than that, it probably doesn't belong in this module.
+//! smarter than that, it belongs to the `ext` submodule.
 //!
 //! Keep in mind that `from_text` functions should be kept private. The public
 //! API should require to assemble every node piecewise. The trick of
 //! `parse(format!())` we use internally is an implementation detail -- long
 //! term, it will be replaced with direct tree manipulation.
 use itertools::Itertools;
-use stdx::format_to;
+use stdx::{format_to, never};
 
 use crate::{ast, AstNode, SourceFile, SyntaxKind, SyntaxNode, SyntaxToken};
 
+/// While the parent module defines basic atomic "constructors", the `ext`
+/// module defines shortcuts for common things.
+///
+/// It's named `ext` rather than `shortcuts` just to keep it short.
+pub mod ext {
+    use super::*;
+
+    pub fn ident_path(ident: &str) -> ast::Path {
+        path_unqualified(path_segment(name_ref(ident)))
+    }
+
+    pub fn expr_unreachable() -> ast::Expr {
+        expr_from_text("unreachable!()")
+    }
+    pub fn expr_todo() -> ast::Expr {
+        expr_from_text("todo!()")
+    }
+    pub fn empty_block_expr() -> ast::BlockExpr {
+        block_expr(None, None)
+    }
+
+    pub fn ty_bool() -> ast::Type {
+        ty_path(ident_path("bool"))
+    }
+    pub fn ty_option(t: ast::Type) -> ast::Type {
+        ty_from_text(&format!("Option<{}>", t))
+    }
+    pub fn ty_result(t: ast::Type, e: ast::Type) -> ast::Type {
+        ty_from_text(&format!("Result<{}, {}>", t, e))
+    }
+}
+
 pub fn name(text: &str) -> ast::Name {
     ast_from_text(&format!("mod {}{};", raw_ident_esc(text), text))
 }
-
 pub fn name_ref(text: &str) -> ast::NameRef {
     ast_from_text(&format!("fn f() {{ {}{}; }}", raw_ident_esc(text), text))
 }
-
 fn raw_ident_esc(ident: &str) -> &'static str {
     let is_keyword = parser::SyntaxKind::from_keyword(ident).is_some();
     if is_keyword && !matches!(ident, "self" | "crate" | "super" | "Self") {
@@ -31,13 +61,23 @@ fn raw_ident_esc(ident: &str) -> &'static str {
     }
 }
 
+pub fn lifetime(text: &str) -> ast::Lifetime {
+    let mut text = text;
+    let tmp;
+    if never!(!text.starts_with('\'')) {
+        tmp = format!("'{}", text);
+        text = &tmp;
+    }
+    ast_from_text(&format!("fn f<{}>() {{ }}", text))
+}
+
 // FIXME: replace stringly-typed constructor with a family of typed ctors, a-la
 // `expr_xxx`.
 pub fn ty(text: &str) -> ast::Type {
-    ast_from_text(&format!("fn f() -> {} {{}}", text))
+    ty_from_text(text)
 }
 pub fn ty_unit() -> ast::Type {
-    ty("()")
+    ty_from_text("()")
 }
 pub fn ty_tuple(types: impl IntoIterator<Item = ast::Type>) -> ast::Type {
     let mut count: usize = 0;
@@ -46,15 +86,16 @@ pub fn ty_tuple(types: impl IntoIterator<Item = ast::Type>) -> ast::Type {
         contents.push(',');
     }
 
-    ty(&format!("({})", contents))
-}
-// FIXME: handle path to type
-pub fn ty_generic(name: ast::NameRef, types: impl IntoIterator<Item = ast::Type>) -> ast::Type {
-    let contents = types.into_iter().join(", ");
-    ty(&format!("{}<{}>", name, contents))
+    ty_from_text(&format!("({})", contents))
 }
 pub fn ty_ref(target: ast::Type, exclusive: bool) -> ast::Type {
-    ty(&if exclusive { format!("&mut {}", target) } else { format!("&{}", target) })
+    ty_from_text(&if exclusive { format!("&mut {}", target) } else { format!("&{}", target) })
+}
+pub fn ty_path(path: ast::Path) -> ast::Type {
+    ty_from_text(&path.to_string())
+}
+fn ty_from_text(text: &str) -> ast::Type {
+    ast_from_text(&format!("type _T = {};", text))
 }
 
 pub fn assoc_item_list() -> ast::AssocItemList {
@@ -88,7 +129,7 @@ pub fn path_unqualified(segment: ast::PathSegment) -> ast::Path {
 pub fn path_qualified(qual: ast::Path, segment: ast::PathSegment) -> ast::Path {
     ast_from_text(&format!("{}::{}", qual, segment))
 }
-
+// FIXME: path concatenation operation doesn't make sense as AST op.
 pub fn path_concat(first: ast::Path, second: ast::Path) -> ast::Path {
     ast_from_text(&format!("{}::{}", first, second))
 }
@@ -104,15 +145,14 @@ pub fn path_from_segments(
         format!("use {};", segments)
     })
 }
-
+// FIXME: should not be pub
 pub fn path_from_text(text: &str) -> ast::Path {
     ast_from_text(&format!("fn main() {{ let test = {}; }}", text))
 }
 
-pub fn glob_use_tree() -> ast::UseTree {
+pub fn use_tree_glob() -> ast::UseTree {
     ast_from_text("use *;")
 }
-
 pub fn use_tree(
     path: ast::Path,
     use_tree_list: Option<ast::UseTreeList>,
@@ -207,15 +247,6 @@ pub fn expr_literal(text: &str) -> ast::Literal {
 pub fn expr_empty_block() -> ast::Expr {
     expr_from_text("{}")
 }
-pub fn expr_unimplemented() -> ast::Expr {
-    expr_from_text("unimplemented!()")
-}
-pub fn expr_unreachable() -> ast::Expr {
-    expr_from_text("unreachable!()")
-}
-pub fn expr_todo() -> ast::Expr {
-    expr_from_text("todo!()")
-}
 pub fn expr_path(path: ast::Path) -> ast::Expr {
     expr_from_text(&path.to_string())
 }
@@ -444,17 +475,6 @@ pub fn expr_stmt(expr: ast::Expr) -> ast::ExprStmt {
     ast_from_text(&format!("fn f() {{ {}{} (); }}", expr, semi))
 }
 
-pub fn token(kind: SyntaxKind) -> SyntaxToken {
-    tokens::SOURCE_FILE
-        .tree()
-        .syntax()
-        .clone_for_update()
-        .descendants_with_tokens()
-        .filter_map(|it| it.into_token())
-        .find(|it| it.kind() == kind)
-        .unwrap_or_else(|| panic!("unhandled token: {:?}", kind))
-}
-
 pub fn param(pat: ast::Pat, ty: ast::Type) -> ast::Param {
     ast_from_text(&format!("fn f({}: {}) {{ }}", pat, ty))
 }
@@ -476,7 +496,7 @@ pub fn param_list(
     ast_from_text(&list)
 }
 
-pub fn generic_param(name: String, ty: Option<ast::TypeBoundList>) -> ast::GenericParam {
+pub fn type_param(name: ast::Name, ty: Option<ast::TypeBoundList>) -> ast::TypeParam {
     let bound = match ty {
         Some(it) => format!(": {}", it),
         None => String::new(),
@@ -484,6 +504,10 @@ pub fn generic_param(name: String, ty: Option<ast::TypeBoundList>) -> ast::Gener
     ast_from_text(&format!("fn f<{}{}>() {{ }}", name, bound))
 }
 
+pub fn lifetime_param(lifetime: ast::Lifetime) -> ast::LifetimeParam {
+    ast_from_text(&format!("fn f<{}>() {{ }}", lifetime))
+}
+
 pub fn generic_param_list(
     pats: impl IntoIterator<Item = ast::GenericParam>,
 ) -> ast::GenericParamList {
@@ -588,6 +612,17 @@ fn unroot(n: SyntaxNode) -> SyntaxNode {
     SyntaxNode::new_root(n.green().into())
 }
 
+pub fn token(kind: SyntaxKind) -> SyntaxToken {
+    tokens::SOURCE_FILE
+        .tree()
+        .syntax()
+        .clone_for_update()
+        .descendants_with_tokens()
+        .filter_map(|it| it.into_token())
+        .find(|it| it.kind() == kind)
+        .unwrap_or_else(|| panic!("unhandled token: {:?}", kind))
+}
+
 pub mod tokens {
     use once_cell::sync::Lazy;