Expose HasSource::source through Semantics with caching behaviour

crates/hir/src/semantics.rs

@@ -25,9 +25,9 @@ use crate::{
     db::HirDatabase,
     semantics::source_to_def::{ChildContainer, SourceToDefCache, SourceToDefCtx},
     source_analyzer::{resolve_hir_path, SourceAnalyzer},
-    Access, AssocItem, Callable, ConstParam, Crate, Field, Function, HirFileId, Impl, InFile,
-    Label, LifetimeParam, Local, MacroDef, Module, ModuleDef, Name, Path, ScopeDef, Trait, Type,
-    TypeAlias, TypeParam, VariantDef,
+    Access, AssocItem, Callable, ConstParam, Crate, Field, Function, HasSource, HirFileId, Impl,
+    InFile, Label, LifetimeParam, Local, MacroDef, Module, ModuleDef, Name, Path, ScopeDef, Trait,
+    Type, TypeAlias, TypeParam, VariantDef,
 };
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -190,6 +190,14 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
         self.imp.descend_node_into_attributes(node)
     }
 
+    /// Search for a definition's source and cache its syntax tree
+    pub fn source<Def: HasSource>(&self, def: Def) -> Option<InFile<Def::Ast>>
+    where
+        Def::Ast: AstNode,
+    {
+        self.imp.source(def)
+    }
+
     pub fn hir_file_for(&self, syntax_node: &SyntaxNode) -> HirFileId {
         self.imp.find_file(syntax_node.clone()).file_id
     }
@@ -845,6 +853,15 @@ impl<'db> SemanticsImpl<'db> {
         SemanticsScope { db: self.db, file_id, resolver }
     }
 
+    fn source<Def: HasSource>(&self, def: Def) -> Option<InFile<Def::Ast>>
+    where
+        Def::Ast: AstNode,
+    {
+        let res = def.source(self.db)?;
+        self.cache(find_root(res.value.syntax()), res.file_id);
+        Some(res)
+    }
+
     fn analyze(&self, node: &SyntaxNode) -> SourceAnalyzer {
         self.analyze_impl(node, None)
     }

crates/ide_assists/src/handlers/inline_call.rs

@@ -1,6 +1,6 @@
 use ast::make;
 use either::Either;
-use hir::{db::HirDatabase, HasSource, PathResolution, Semantics, TypeInfo};
+use hir::{db::HirDatabase, PathResolution, Semantics, TypeInfo};
 use ide_db::{
     base_db::{FileId, FileRange},
     defs::Definition,
@@ -194,7 +194,7 @@ pub(crate) fn inline_call(acc: &mut Assists, ctx: &AssistContext) -> Option<()>
         }
     };
 
-    let fn_source = function.source(ctx.db())?;
+    let fn_source = ctx.sema.source(function)?;
     let fn_body = fn_source.value.body()?;
     let param_list = fn_source.value.param_list()?;
 

crates/ide_assists/src/handlers/replace_let_with_if_let.rs

@@ -38,7 +38,7 @@ use crate::{AssistContext, AssistId, AssistKind, Assists};
 // ```
 pub(crate) fn replace_let_with_if_let(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let let_kw = ctx.find_token_syntax_at_offset(T![let])?;
-    let let_stmt = let_kw.ancestors().find_map(ast::LetStmt::cast)?;
+    let let_stmt = let_kw.parent().and_then(ast::LetStmt::cast)?;
     let init = let_stmt.initializer()?;
     let original_pat = let_stmt.pat()?;
 

crates/ide_completion/src/completions/trait_impl.rs

@@ -185,7 +185,7 @@ fn get_transformed_assoc_item(
     let assoc_item = assoc_item.clone_for_update();
     let trait_ = impl_def.trait_(ctx.db)?;
     let source_scope = &ctx.sema.scope_for_def(trait_);
-    let target_scope = &ctx.sema.scope(impl_def.source(ctx.db)?.syntax().value);
+    let target_scope = &ctx.sema.scope(ctx.sema.source(impl_def)?.syntax().value);
     let transform = PathTransform::trait_impl(
         target_scope,
         source_scope,