Feat: inline generics in const and func trait completions

3 files changed, 2 insertions, 165 deletions

diff --git a/crates/ide_assists/src/lib.rs b/crates/ide_assists/src/lib.rs
index fa378a622..86a57ce5d 100644
--- a/crates/ide_assists/src/lib.rs
+++ b/crates/ide_assists/src/lib.rs
@@ -15,7 +15,6 @@ mod assist_context;
 #[cfg(test)]
 mod tests;
 pub mod utils;
-pub mod path_transform;
 
 use hir::Semantics;
 use ide_db::{base_db::FileRange, RootDatabase};
diff --git a/crates/ide_assists/src/path_transform.rs b/crates/ide_assists/src/path_transform.rs
deleted file mode 100644
index 48a7fa06a..000000000
--- a/crates/ide_assists/src/path_transform.rs
+++ /dev/null
@@ -1,160 +0,0 @@
-//! See [`PathTransform`].
-
-use hir::{HirDisplay, SemanticsScope};
-use ide_db::helpers::mod_path_to_ast;
-use rustc_hash::FxHashMap;
-use syntax::{
-    ast::{self, AstNode},
-    ted,
-};
-
-/// `PathTransform` substitutes path in SyntaxNodes in bulk.
-///
-/// This is mostly useful for IDE code generation. If you paste some existing
-/// code into a new context (for example, to add method overrides to an `impl`
-/// block), you generally want to appropriately qualify the names, and sometimes
-/// you might want to substitute generic parameters as well:
-///
-/// ```
-/// mod x {
-///   pub struct A<V>;
-///   pub trait T<U> { fn foo(&self, _: U) -> A<U>; }
-/// }
-///
-/// mod y {
-///   use x::T;
-///
-///   impl T<()> for () {
-///      // If we invoke **Add Missing Members** here, we want to copy-paste `foo`.
-///      // But we want a slightly-modified version of it:
-///      fn foo(&self, _: ()) -> x::A<()> {}
-///   }
-/// }
-/// ```
-pub(crate) struct PathTransform<'a> {
-    pub(crate) subst: (hir::Trait, ast::Impl),
-    pub(crate) target_scope: &'a SemanticsScope<'a>,
-    pub(crate) source_scope: &'a SemanticsScope<'a>,
-}
-
-impl<'a> PathTransform<'a> {
-    pub(crate) fn apply(&self, item: ast::AssocItem) {
-        if let Some(ctx) = self.build_ctx() {
-            ctx.apply(item)
-        }
-    }
-    fn build_ctx(&self) -> Option<Ctx<'a>> {
-        let db = self.source_scope.db;
-        let target_module = self.target_scope.module()?;
-        let source_module = self.source_scope.module()?;
-
-        let substs = get_syntactic_substs(self.subst.1.clone()).unwrap_or_default();
-        let generic_def: hir::GenericDef = self.subst.0.into();
-        let substs_by_param: FxHashMap<_, _> = generic_def
-            .type_params(db)
-            .into_iter()
-            // this is a trait impl, so we need to skip the first type parameter -- this is a bit hacky
-            .skip(1)
-            // The actual list of trait type parameters may be longer than the one
-            // used in the `impl` block due to trailing default type parameters.
-            // For that case we extend the `substs` with an empty iterator so we
-            // can still hit those trailing values and check if they actually have
-            // a default type. If they do, go for that type from `hir` to `ast` so
-            // the resulting change can be applied correctly.
-            .zip(substs.into_iter().map(Some).chain(std::iter::repeat(None)))
-            .filter_map(|(k, v)| match v {
-                Some(v) => Some((k, v)),
-                None => {
-                    let default = k.default(db)?;
-                    Some((
-                        k,
-                        ast::make::ty(&default.display_source_code(db, source_module.into()).ok()?),
-                    ))
-                }
-            })
-            .collect();
-
-        let res = Ctx { substs: substs_by_param, target_module, source_scope: self.source_scope };
-        Some(res)
-    }
-}
-
-struct Ctx<'a> {
-    substs: FxHashMap<hir::TypeParam, ast::Type>,
-    target_module: hir::Module,
-    source_scope: &'a SemanticsScope<'a>,
-}
-
-impl<'a> Ctx<'a> {
-    fn apply(&self, item: ast::AssocItem) {
-        for event in item.syntax().preorder() {
-            let node = match event {
-                syntax::WalkEvent::Enter(_) => continue,
-                syntax::WalkEvent::Leave(it) => it,
-            };
-            if let Some(path) = ast::Path::cast(node.clone()) {
-                self.transform_path(path);
-            }
-        }
-    }
-    fn transform_path(&self, path: ast::Path) -> Option<()> {
-        if path.qualifier().is_some() {
-            return None;
-        }
-        if path.segment().and_then(|s| s.param_list()).is_some() {
-            // don't try to qualify `Fn(Foo) -> Bar` paths, they are in prelude anyway
-            return None;
-        }
-
-        let resolution = self.source_scope.speculative_resolve(&path)?;
-
-        match resolution {
-            hir::PathResolution::TypeParam(tp) => {
-                if let Some(subst) = self.substs.get(&tp) {
-                    ted::replace(path.syntax(), subst.clone_subtree().clone_for_update().syntax())
-                }
-            }
-            hir::PathResolution::Def(def) => {
-                let found_path =
-                    self.target_module.find_use_path(self.source_scope.db.upcast(), def)?;
-                let res = mod_path_to_ast(&found_path).clone_for_update();
-                if let Some(args) = path.segment().and_then(|it| it.generic_arg_list()) {
-                    if let Some(segment) = res.segment() {
-                        let old = segment.get_or_create_generic_arg_list();
-                        ted::replace(old.syntax(), args.clone_subtree().syntax().clone_for_update())
-                    }
-                }
-                ted::replace(path.syntax(), res.syntax())
-            }
-            hir::PathResolution::Local(_)
-            | hir::PathResolution::ConstParam(_)
-            | hir::PathResolution::SelfType(_)
-            | hir::PathResolution::Macro(_)
-            | hir::PathResolution::AssocItem(_) => (),
-        }
-        Some(())
-    }
-}
-
-// FIXME: It would probably be nicer if we could get this via HIR (i.e. get the
-// trait ref, and then go from the types in the substs back to the syntax).
-fn get_syntactic_substs(impl_def: ast::Impl) -> Option<Vec<ast::Type>> {
-    let target_trait = impl_def.trait_()?;
-    let path_type = match target_trait {
-        ast::Type::PathType(path) => path,
-        _ => return None,
-    };
-    let generic_arg_list = path_type.path()?.segment()?.generic_arg_list()?;
-
-    let mut result = Vec::new();
-    for generic_arg in generic_arg_list.generic_args() {
-        match generic_arg {
-            ast::GenericArg::TypeArg(type_arg) => result.push(type_arg.ty()?),
-            ast::GenericArg::AssocTypeArg(_)
-            | ast::GenericArg::LifetimeArg(_)
-            | ast::GenericArg::ConstArg(_) => (),
-        }
-    }
-
-    Some(result)
-}
diff --git a/crates/ide_assists/src/utils.rs b/crates/ide_assists/src/utils.rs
index 068df005b..0ec236aa0 100644
--- a/crates/ide_assists/src/utils.rs
+++ b/crates/ide_assists/src/utils.rs
@@ -8,6 +8,7 @@ use ast::TypeBoundsOwner;
 use hir::{Adt, HasSource, Semantics};
 use ide_db::{
     helpers::{FamousDefs, SnippetCap},
+    path_transform::PathTransform,
     RootDatabase,
 };
 use itertools::Itertools;
@@ -22,10 +23,7 @@ use syntax::{
     SyntaxNode, TextSize, T,
 };
 
-use crate::{
-    assist_context::{AssistBuilder, AssistContext},
-    path_transform::PathTransform,
-};
+use crate::assist_context::{AssistBuilder, AssistContext};
 
 pub(crate) fn unwrap_trivial_block(block: ast::BlockExpr) -> ast::Expr {
     extract_trivial_expression(&block)