15 files changed, 242 insertions, 115 deletions

diff --git a/crates/ra_hir/src/code_model_impl/module.rs b/crates/ra_hir/src/code_model_impl/module.rs
index 480ec27bf..418d59c91 100644
--- a/crates/ra_hir/src/code_model_impl/module.rs
+++ b/crates/ra_hir/src/code_model_impl/module.rs
@@ -25,9 +25,10 @@ impl Module {
 
     pub(crate) fn definition_source_impl(&self, db: &impl HirDatabase) -> (FileId, ModuleSource) {
         let module_tree = db.module_tree(self.krate);
-        let source = self.module_id.source(&module_tree);
-        let module_source = ModuleSource::from_source_item_id(db, source);
-        let file_id = source.file_id.as_original_file();
+        let file_id = self.module_id.file_id(&module_tree);
+        let decl_id = self.module_id.decl_id(&module_tree);
+        let module_source = ModuleSource::new(db, file_id, decl_id);
+        let file_id = file_id.as_original_file();
         (file_id, module_source)
     }
 
@@ -39,8 +40,7 @@ impl Module {
         let link = self.module_id.parent_link(&module_tree)?;
         let file_id = link
             .owner(&module_tree)
-            .source(&module_tree)
-            .file_id
+            .file_id(&module_tree)
             .as_original_file();
         let src = link.source(&module_tree, db);
         Some((file_id, src))
diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index 5df4bd4a1..3f76b769d 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -16,6 +16,7 @@ use crate::{
     adt::{StructData, EnumData},
     impl_block::ModuleImplBlocks,
     generics::{GenericParams, GenericDef},
+    ids::SourceFileItemId,
 };
 
 #[salsa::query_group(HirDatabaseStorage)]
@@ -51,7 +52,11 @@ pub trait HirDatabase: SourceDatabase + AsRef<HirInterner> {
     fn file_item(&self, source_item_id: SourceItemId) -> TreeArc<SyntaxNode>;
 
     #[salsa::invoke(crate::module_tree::Submodule::submodules_query)]
-    fn submodules(&self, source: SourceItemId) -> Arc<Vec<crate::module_tree::Submodule>>;
+    fn submodules(
+        &self,
+        file_id: HirFileId,
+        delc_id: Option<SourceFileItemId>,
+    ) -> Arc<Vec<crate::module_tree::Submodule>>;
 
     #[salsa::invoke(crate::nameres::lower::LoweredModule::lower_module_query)]
     fn lower_module(&self, module: Module) -> (Arc<LoweredModule>, Arc<ImportSourceMap>);
diff --git a/crates/ra_hir/src/expr.rs b/crates/ra_hir/src/expr.rs
index 29469af2c..60d997bbe 100644
--- a/crates/ra_hir/src/expr.rs
+++ b/crates/ra_hir/src/expr.rs
@@ -498,7 +498,13 @@ impl ExprCollector {
                     let then_branch = self.collect_block_opt(e.then_branch());
                     let else_branch = e
                         .else_branch()
-                        .map(|e| self.collect_block(e))
+                        .map(|b| match b {
+                            ast::ElseBranchFlavor::Block(it) => self.collect_block(it),
+                            ast::ElseBranchFlavor::IfExpr(elif) => {
+                                let expr: &ast::Expr = ast::Expr::cast(elif.syntax()).unwrap();
+                                self.collect_expr(expr)
+                            }
+                        })
                         .unwrap_or_else(|| self.empty_block());
                     let placeholder_pat = self.pats.alloc(Pat::Missing);
                     let arms = vec![
@@ -521,7 +527,13 @@ impl ExprCollector {
                 } else {
                     let condition = self.collect_expr_opt(e.condition().and_then(|c| c.expr()));
                     let then_branch = self.collect_block_opt(e.then_branch());
-                    let else_branch = e.else_branch().map(|e| self.collect_block(e));
+                    let else_branch = e.else_branch().map(|b| match b {
+                        ast::ElseBranchFlavor::Block(it) => self.collect_block(it),
+                        ast::ElseBranchFlavor::IfExpr(elif) => {
+                            let expr: &ast::Expr = ast::Expr::cast(elif.syntax()).unwrap();
+                            self.collect_expr(expr)
+                        }
+                    });
                     self.alloc_expr(
                         Expr::If {
                             condition,
diff --git a/crates/ra_hir/src/ids.rs b/crates/ra_hir/src/ids.rs
index 7dd4b540e..0e4dc6261 100644
--- a/crates/ra_hir/src/ids.rs
+++ b/crates/ra_hir/src/ids.rs
@@ -4,7 +4,7 @@ use std::{
 };
 
 use ra_db::{LocationIntener, FileId};
-use ra_syntax::{TreeArc, SyntaxNode, SourceFile, AstNode, ast};
+use ra_syntax::{TreeArc, SyntaxNode, SourceFile, AstNode, SyntaxNodePtr, ast};
 use ra_arena::{Arena, RawId, ArenaId, impl_arena_id};
 
 use crate::{
@@ -203,7 +203,7 @@ pub(crate) trait AstItemDef<N: AstNode>: ArenaId + Clone {
         let items = ctx.db.file_items(ctx.file_id);
         let raw = SourceItemId {
             file_id: ctx.file_id,
-            item_id: Some(items.id_of(ctx.file_id, ast.syntax())),
+            item_id: items.id_of(ctx.file_id, ast.syntax()),
         };
         let loc = ItemLoc {
             module: ctx.module,
@@ -301,15 +301,14 @@ impl_arena_id!(SourceFileItemId);
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct SourceItemId {
     pub(crate) file_id: HirFileId,
-    /// None for the whole file.
-    pub(crate) item_id: Option<SourceFileItemId>,
+    pub(crate) item_id: SourceFileItemId,
 }
 
 /// Maps items' `SyntaxNode`s to `SourceFileItemId`s and back.
 #[derive(Debug, PartialEq, Eq)]
 pub struct SourceFileItems {
     file_id: HirFileId,
-    arena: Arena<SourceFileItemId, TreeArc<SyntaxNode>>,
+    arena: Arena<SourceFileItemId, SyntaxNodePtr>,
 }
 
 impl SourceFileItems {
@@ -329,15 +328,15 @@ impl SourceFileItems {
         // trait does not chage ids of top-level items, which helps caching.
         bfs(source_file.syntax(), |it| {
             if let Some(module_item) = ast::ModuleItem::cast(it) {
-                self.alloc(module_item.syntax().to_owned());
+                self.alloc(module_item.syntax());
             } else if let Some(macro_call) = ast::MacroCall::cast(it) {
-                self.alloc(macro_call.syntax().to_owned());
+                self.alloc(macro_call.syntax());
             }
         })
     }
 
-    fn alloc(&mut self, item: TreeArc<SyntaxNode>) -> SourceFileItemId {
-        self.arena.alloc(item)
+    fn alloc(&mut self, item: &SyntaxNode) -> SourceFileItemId {
+        self.arena.alloc(SyntaxNodePtr::new(item))
     }
     pub(crate) fn id_of(&self, file_id: HirFileId, item: &SyntaxNode) -> SourceFileItemId {
         assert_eq!(
@@ -348,17 +347,8 @@ impl SourceFileItems {
         self.id_of_unchecked(item)
     }
     pub(crate) fn id_of_unchecked(&self, item: &SyntaxNode) -> SourceFileItemId {
-        if let Some((id, _)) = self.arena.iter().find(|(_id, i)| *i == item) {
-            return id;
-        }
-        // This should not happen. Let's try to give a sensible diagnostics.
-        if let Some((id, i)) = self.arena.iter().find(|(_id, i)| i.range() == item.range()) {
-            // FIXME(#288): whyyy are we getting here?
-            log::error!(
-                "unequal syntax nodes with the same range:\n{:?}\n{:?}",
-                item,
-                i
-            );
+        let ptr = SyntaxNodePtr::new(item);
+        if let Some((id, _)) = self.arena.iter().find(|(_id, i)| **i == ptr) {
             return id;
         }
         panic!(
@@ -367,15 +357,11 @@ impl SourceFileItems {
             self.arena.iter().map(|(_id, i)| i).collect::<Vec<_>>(),
         );
     }
-    pub fn id_of_parse(&self) -> SourceFileItemId {
-        let (id, _syntax) = self.arena.iter().next().unwrap();
-        id
-    }
 }
 
 impl std::ops::Index<SourceFileItemId> for SourceFileItems {
-    type Output = SyntaxNode;
-    fn index(&self, idx: SourceFileItemId) -> &SyntaxNode {
+    type Output = SyntaxNodePtr;
+    fn index(&self, idx: SourceFileItemId) -> &SyntaxNodePtr {
         &self.arena[idx]
     }
 }
diff --git a/crates/ra_hir/src/marks.rs b/crates/ra_hir/src/marks.rs
index 338ed0516..d704c3adb 100644
--- a/crates/ra_hir/src/marks.rs
+++ b/crates/ra_hir/src/marks.rs
@@ -1,4 +1,6 @@
 test_utils::marks!(
     name_res_works_for_broken_modules
     item_map_enum_importing
+    type_var_cycles_resolve_completely
+    type_var_cycles_resolve_as_possible
 );
diff --git a/crates/ra_hir/src/module_tree.rs b/crates/ra_hir/src/module_tree.rs
index d5ad9decb..d1dc3fa4b 100644
--- a/crates/ra_hir/src/module_tree.rs
+++ b/crates/ra_hir/src/module_tree.rs
@@ -11,21 +11,28 @@ use ra_syntax::{
 use ra_arena::{Arena, RawId, impl_arena_id};
 use test_utils::tested_by;
 
-use crate::{Name, AsName, HirDatabase, SourceItemId, HirFileId, Problem, SourceFileItems, ModuleSource};
+use crate::{
+    Name, AsName, HirDatabase, SourceItemId, HirFileId, Problem, SourceFileItems, ModuleSource,
+    ids::SourceFileItemId,
+};
 
 impl ModuleSource {
-    pub(crate) fn from_source_item_id(
+    pub(crate) fn new(
         db: &impl HirDatabase,
-        source_item_id: SourceItemId,
+        file_id: HirFileId,
+        decl_id: Option<SourceFileItemId>,
     ) -> ModuleSource {
-        let module_syntax = db.file_item(source_item_id);
-        if let Some(source_file) = ast::SourceFile::cast(&module_syntax) {
-            ModuleSource::SourceFile(source_file.to_owned())
-        } else if let Some(module) = ast::Module::cast(&module_syntax) {
-            assert!(module.item_list().is_some(), "expected inline module");
-            ModuleSource::Module(module.to_owned())
-        } else {
-            panic!("expected file or inline module")
+        match decl_id {
+            Some(item_id) => {
+                let module = db.file_item(SourceItemId { file_id, item_id });
+                let module = ast::Module::cast(&*module).unwrap();
+                assert!(module.item_list().is_some(), "expected inline module");
+                ModuleSource::Module(module.to_owned())
+            }
+            None => {
+                let source_file = db.hir_parse(file_id);
+                ModuleSource::SourceFile(source_file)
+            }
         }
     }
 }
@@ -34,18 +41,18 @@ impl ModuleSource {
 pub struct Submodule {
     name: Name,
     is_declaration: bool,
-    source: SourceItemId,
+    decl_id: SourceFileItemId,
 }
 
 impl Submodule {
     pub(crate) fn submodules_query(
         db: &impl HirDatabase,
-        source: SourceItemId,
+        file_id: HirFileId,
+        decl_id: Option<SourceFileItemId>,
     ) -> Arc<Vec<Submodule>> {
         db.check_canceled();
-        let file_id = source.file_id;
         let file_items = db.file_items(file_id);
-        let module_source = ModuleSource::from_source_item_id(db, source);
+        let module_source = ModuleSource::new(db, file_id, decl_id);
         let submodules = match module_source {
             ModuleSource::SourceFile(source_file) => {
                 collect_submodules(file_id, &file_items, &*source_file)
@@ -54,6 +61,7 @@ impl Submodule {
                 collect_submodules(file_id, &file_items, module.item_list().unwrap())
             }
         };
+
         return Arc::new(submodules);
 
         fn collect_submodules(
@@ -75,10 +83,7 @@ impl Submodule {
                     let sub = Submodule {
                         name,
                         is_declaration: module.has_semi(),
-                        source: SourceItemId {
-                            file_id,
-                            item_id: Some(file_items.id_of(file_id, module.syntax())),
-                        },
+                        decl_id: file_items.id_of(file_id, module.syntax()),
                     };
                     Some(sub)
                 })
@@ -110,7 +115,9 @@ pub struct ModuleTree {
 
 #[derive(Debug, PartialEq, Eq, Hash)]
 pub struct ModuleData {
-    source: SourceItemId,
+    file_id: HirFileId,
+    /// Points to `ast::Module`, `None` for the whole file.
+    decl_id: Option<SourceFileItemId>,
     parent: Option<LinkId>,
     children: Vec<LinkId>,
 }
@@ -136,8 +143,15 @@ impl ModuleTree {
         self.mods.iter().map(|(id, _)| id)
     }
 
-    pub(crate) fn find_module_by_source(&self, source: SourceItemId) -> Option<ModuleId> {
-        let (res, _) = self.mods.iter().find(|(_, m)| m.source == source)?;
+    pub(crate) fn find_module_by_source(
+        &self,
+        file_id: HirFileId,
+        decl_id: Option<SourceFileItemId>,
+    ) -> Option<ModuleId> {
+        let (res, _) = self
+            .mods
+            .iter()
+            .find(|(_, m)| (m.file_id, m.decl_id) == (file_id, decl_id))?;
         Some(res)
     }
 
@@ -147,11 +161,7 @@ impl ModuleTree {
         let source_root_id = db.file_source_root(file_id);
 
         let source_root = db.source_root(source_root_id);
-        let source = SourceItemId {
-            file_id: file_id.into(),
-            item_id: None,
-        };
-        self.init_subtree(db, &source_root, None, source);
+        self.init_subtree(db, &source_root, None, file_id.into(), None);
     }
 
     fn init_subtree(
@@ -159,16 +169,21 @@ impl ModuleTree {
         db: &impl HirDatabase,
         source_root: &SourceRoot,
         parent: Option<LinkId>,
-        source: SourceItemId,
+        file_id: HirFileId,
+        decl_id: Option<SourceFileItemId>,
     ) -> ModuleId {
         let id = self.alloc_mod(ModuleData {
-            source,
+            file_id,
+            decl_id,
             parent,
             children: Vec::new(),
         });
-        for sub in db.submodules(source).iter() {
+        for sub in db.submodules(file_id, decl_id).iter() {
             let link = self.alloc_link(LinkData {
-                source: sub.source,
+                source: SourceItemId {
+                    file_id,
+                    item_id: sub.decl_id,
+                },
                 name: sub.name.clone(),
                 owner: id,
                 points_to: Vec::new(),
@@ -176,24 +191,17 @@ impl ModuleTree {
             });
 
             let (points_to, problem) = if sub.is_declaration {
-                let (points_to, problem) = resolve_submodule(db, source.file_id, &sub.name);
+                let (points_to, problem) = resolve_submodule(db, file_id, &sub.name);
                 let points_to = points_to
                     .into_iter()
                     .map(|file_id| {
-                        self.init_subtree(
-                            db,
-                            source_root,
-                            Some(link),
-                            SourceItemId {
-                                file_id: file_id.into(),
-                                item_id: None,
-                            },
-                        )
+                        self.init_subtree(db, source_root, Some(link), file_id.into(), None)
                     })
                     .collect::<Vec<_>>();
                 (points_to, problem)
             } else {
-                let points_to = self.init_subtree(db, source_root, Some(link), sub.source);
+                let points_to =
+                    self.init_subtree(db, source_root, Some(link), file_id, Some(sub.decl_id));
                 (vec![points_to], None)
             };
 
@@ -216,8 +224,11 @@ impl ModuleTree {
 }
 
 impl ModuleId {
-    pub(crate) fn source(self, tree: &ModuleTree) -> SourceItemId {
-        tree.mods[self].source
+    pub(crate) fn file_id(self, tree: &ModuleTree) -> HirFileId {
+        tree.mods[self].file_id
+    }
+    pub(crate) fn decl_id(self, tree: &ModuleTree) -> Option<SourceFileItemId> {
+        tree.mods[self].decl_id
     }
     pub(crate) fn parent_link(self, tree: &ModuleTree) -> Option<LinkId> {
         tree.mods[self].parent
diff --git a/crates/ra_hir/src/nameres.rs b/crates/ra_hir/src/nameres.rs
index 5193900e0..97ce6c946 100644
--- a/crates/ra_hir/src/nameres.rs
+++ b/crates/ra_hir/src/nameres.rs
@@ -215,7 +215,7 @@ where
         // Populate extern crates prelude
         {
             let root_id = module_id.crate_root(&self.module_tree);
-            let file_id = root_id.source(&self.module_tree).file_id;
+            let file_id = root_id.file_id(&self.module_tree);
             let crate_graph = self.db.crate_graph();
             if let Some(crate_id) = crate_graph.crate_id_for_crate_root(file_id.as_original_file())
             {
diff --git a/crates/ra_hir/src/nameres/lower.rs b/crates/ra_hir/src/nameres/lower.rs
index 1d77548f3..8df11a5f4 100644
--- a/crates/ra_hir/src/nameres/lower.rs
+++ b/crates/ra_hir/src/nameres/lower.rs
@@ -121,10 +121,7 @@ impl LoweredModule {
                     let item_id = file_items.id_of_unchecked(macro_call.syntax());
                     let loc = MacroCallLoc {
                         module,
-                        source_item_id: SourceItemId {
-                            file_id,
-                            item_id: Some(item_id),
-                        },
+                        source_item_id: SourceItemId { file_id, item_id },
                     };
                     let id = loc.id(db);
                     let file_id = HirFileId::from(id);
diff --git a/crates/ra_hir/src/query_definitions.rs b/crates/ra_hir/src/query_definitions.rs
index 61c93a964..bf9ac0dfb 100644
--- a/crates/ra_hir/src/query_definitions.rs
+++ b/crates/ra_hir/src/query_definitions.rs
@@ -4,9 +4,7 @@ use std::{
 };
 
 use rustc_hash::FxHashMap;
-use ra_syntax::{
-    AstNode, SyntaxNode, TreeArc,
-};
+use ra_syntax::{SyntaxNode, TreeArc};
 use ra_db::{CrateId};
 
 use crate::{
@@ -32,10 +30,10 @@ pub(super) fn file_item(
     db: &impl HirDatabase,
     source_item_id: SourceItemId,
 ) -> TreeArc<SyntaxNode> {
-    match source_item_id.item_id {
-        Some(id) => db.file_items(source_item_id.file_id)[id].to_owned(),
-        None => db.hir_parse(source_item_id.file_id).syntax().to_owned(),
-    }
+    let source_file = db.hir_parse(source_item_id.file_id);
+    db.file_items(source_item_id.file_id)[source_item_id.item_id]
+        .to_node(&source_file)
+        .to_owned()
 }
 
 pub(super) fn item_map(db: &impl HirDatabase, crate_id: CrateId) -> Arc<ItemMap> {
diff --git a/crates/ra_hir/src/source_binder.rs b/crates/ra_hir/src/source_binder.rs
index c0b3f1cd4..f523f0647 100644
--- a/crates/ra_hir/src/source_binder.rs
+++ b/crates/ra_hir/src/source_binder.rs
@@ -13,18 +13,14 @@ use ra_syntax::{
 };
 
 use crate::{
-    HirDatabase, Function, SourceItemId, ModuleDef,
-    AsName, Module,
-    ids::LocationCtx,
+    HirDatabase, Function, ModuleDef,
+    AsName, Module, HirFileId,
+    ids::{LocationCtx, SourceFileItemId},
 };
 
 /// Locates the module by `FileId`. Picks topmost module in the file.
 pub fn module_from_file_id(db: &impl HirDatabase, file_id: FileId) -> Option<Module> {
-    let module_source = SourceItemId {
-        file_id: file_id.into(),
-        item_id: None,
-    };
-    module_from_source(db, module_source)
+    module_from_source(db, file_id.into(), None)
 }
 
 /// Locates the child module by `mod child;` declaration.
@@ -59,11 +55,7 @@ fn module_from_inline(
     let file_id = file_id.into();
     let file_items = db.file_items(file_id);
     let item_id = file_items.id_of(file_id, module.syntax());
-    let source = SourceItemId {
-        file_id,
-        item_id: Some(item_id),
-    };
-    module_from_source(db, source)
+    module_from_source(db, file_id, Some(item_id))
 }
 
 /// Locates the module by child syntax element within the module
@@ -83,13 +75,17 @@ pub fn module_from_child_node(
     }
 }
 
-fn module_from_source(db: &impl HirDatabase, source: SourceItemId) -> Option<Module> {
-    let source_root_id = db.file_source_root(source.file_id.as_original_file());
+fn module_from_source(
+    db: &impl HirDatabase,
+    file_id: HirFileId,
+    decl_id: Option<SourceFileItemId>,
+) -> Option<Module> {
+    let source_root_id = db.file_source_root(file_id.as_original_file());
     db.source_root_crates(source_root_id)
         .iter()
         .find_map(|&krate| {
             let module_tree = db.module_tree(krate);
-            let module_id = module_tree.find_module_by_source(source)?;
+            let module_id = module_tree.find_module_by_source(file_id, decl_id)?;
             Some(Module { krate, module_id })
         })
 }
diff --git a/crates/ra_hir/src/ty.rs b/crates/ra_hir/src/ty.rs
index 179ebddee..31ea45706 100644
--- a/crates/ra_hir/src/ty.rs
+++ b/crates/ra_hir/src/ty.rs
@@ -29,6 +29,8 @@ use ra_arena::map::ArenaMap;
 use join_to_string::join;
 use rustc_hash::FxHashMap;
 
+use test_utils::tested_by;
+
 use crate::{
     Module, Function, Struct, StructField, Enum, EnumVariant, Path, Name, ImplBlock,
     FnSignature, FnScopes, ModuleDef, AdtDef,
@@ -862,14 +864,15 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
     }
 
     fn resolve_all(mut self) -> InferenceResult {
+        let mut tv_stack = Vec::new();
         let mut expr_types = mem::replace(&mut self.type_of_expr, ArenaMap::default());
         for ty in expr_types.values_mut() {
-            let resolved = self.resolve_ty_completely(mem::replace(ty, Ty::Unknown));
+            let resolved = self.resolve_ty_completely(&mut tv_stack, mem::replace(ty, Ty::Unknown));
             *ty = resolved;
         }
         let mut pat_types = mem::replace(&mut self.type_of_pat, ArenaMap::default());
         for ty in pat_types.values_mut() {
-            let resolved = self.resolve_ty_completely(mem::replace(ty, Ty::Unknown));
+            let resolved = self.resolve_ty_completely(&mut tv_stack, mem::replace(ty, Ty::Unknown));
             *ty = resolved;
         }
         InferenceResult {
@@ -1014,13 +1017,21 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
     /// by their known types. All types returned by the infer_* functions should
     /// be resolved as far as possible, i.e. contain no type variables with
     /// known type.
-    fn resolve_ty_as_possible(&mut self, ty: Ty) -> Ty {
+    fn resolve_ty_as_possible(&mut self, tv_stack: &mut Vec<TypeVarId>, ty: Ty) -> Ty {
         ty.fold(&mut |ty| match ty {
             Ty::Infer(tv) => {
                 let inner = tv.to_inner();
+                if tv_stack.contains(&inner) {
+                    tested_by!(type_var_cycles_resolve_as_possible);
+                    // recursive type
+                    return tv.fallback_value();
+                }
                 if let Some(known_ty) = self.var_unification_table.probe_value(inner).known() {
                     // known_ty may contain other variables that are known by now
-                    self.resolve_ty_as_possible(known_ty.clone())
+                    tv_stack.push(inner);
+                    let result = self.resolve_ty_as_possible(tv_stack, known_ty.clone());
+                    tv_stack.pop();
+                    result
                 } else {
                     ty
                 }
@@ -1049,13 +1060,21 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
 
     /// Resolves the type completely; type variables without known type are
     /// replaced by Ty::Unknown.
-    fn resolve_ty_completely(&mut self, ty: Ty) -> Ty {
+    fn resolve_ty_completely(&mut self, tv_stack: &mut Vec<TypeVarId>, ty: Ty) -> Ty {
         ty.fold(&mut |ty| match ty {
             Ty::Infer(tv) => {
                 let inner = tv.to_inner();
+                if tv_stack.contains(&inner) {
+                    tested_by!(type_var_cycles_resolve_completely);
+                    // recursive type
+                    return tv.fallback_value();
+                }
                 if let Some(known_ty) = self.var_unification_table.probe_value(inner).known() {
                     // known_ty may contain other variables that are known by now
-                    self.resolve_ty_completely(known_ty.clone())
+                    tv_stack.push(inner);
+                    let result = self.resolve_ty_completely(tv_stack, known_ty.clone());
+                    tv_stack.pop();
+                    result
                 } else {
                     tv.fallback_value()
                 }
@@ -1070,7 +1089,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
             let name = path.as_ident().cloned().unwrap_or_else(Name::self_param);
             if let Some(scope_entry) = self.scopes.resolve_local_name(expr, name) {
                 let ty = self.type_of_pat.get(scope_entry.pat())?;
-                let ty = self.resolve_ty_as_possible(ty.clone());
+                let ty = self.resolve_ty_as_possible(&mut vec![], ty.clone());
                 return Some(ty);
             };
         };
@@ -1239,7 +1258,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         // use a new type variable if we got Ty::Unknown here
         let ty = self.insert_type_vars_shallow(ty);
         self.unify(&ty, expected);
-        let ty = self.resolve_ty_as_possible(ty);
+        let ty = self.resolve_ty_as_possible(&mut vec![], ty);
         self.write_pat_ty(pat, ty.clone());
         ty
     }
@@ -1538,7 +1557,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         // use a new type variable if we got Ty::Unknown here
         let ty = self.insert_type_vars_shallow(ty);
         self.unify(&ty, &expected.ty);
-        let ty = self.resolve_ty_as_possible(ty);
+        let ty = self.resolve_ty_as_possible(&mut vec![], ty);
         self.write_expr_ty(tgt_expr, ty.clone());
         ty
     }
diff --git a/crates/ra_hir/src/ty/snapshots/tests__infer_in_elseif.snap b/crates/ra_hir/src/ty/snapshots/tests__infer_in_elseif.snap
new file mode 100644
index 000000000..6a435e5cf
--- /dev/null
+++ b/crates/ra_hir/src/ty/snapshots/tests__infer_in_elseif.snap
@@ -0,0 +1,17 @@
+---
+created: "2019-01-26T21:36:52.714121185+00:00"
+creator: [email protected]
+expression: "&result"
+source: crates/ra_hir/src/ty/tests.rs
+---
+[35; 38) 'foo': Foo
+[45; 109) '{     ...   } }': ()
+[51; 107) 'if tru...     }': ()
+[54; 58) 'true': bool
+[59; 67) '{      }': ()
+[73; 107) 'if fal...     }': i32
+[76; 81) 'false': bool
+[82; 107) '{     ...     }': i32
+[92; 95) 'foo': Foo
+[92; 101) 'foo.field': i32
+
diff --git a/crates/ra_hir/src/ty/snapshots/tests__recursive_vars.snap b/crates/ra_hir/src/ty/snapshots/tests__recursive_vars.snap
new file mode 100644
index 000000000..c3227ff7e
--- /dev/null
+++ b/crates/ra_hir/src/ty/snapshots/tests__recursive_vars.snap
@@ -0,0 +1,14 @@
+---
+created: "2019-01-26T22:42:22.329980185+00:00"
+creator: [email protected]
+expression: "&result"
+source: crates/ra_hir/src/ty/tests.rs
+---
+[11; 48) '{     ...&y]; }': ()
+[21; 22) 'y': &[unknown]
+[25; 32) 'unknown': &[unknown]
+[38; 45) '[y, &y]': [&&[unknown]]
+[39; 40) 'y': &[unknown]
+[42; 44) '&y': &&[unknown]
+[43; 44) 'y': &[unknown]
+
diff --git a/crates/ra_hir/src/ty/snapshots/tests__recursive_vars_2.snap b/crates/ra_hir/src/ty/snapshots/tests__recursive_vars_2.snap
new file mode 100644
index 000000000..de124da5b
--- /dev/null
+++ b/crates/ra_hir/src/ty/snapshots/tests__recursive_vars_2.snap
@@ -0,0 +1,21 @@
+---
+created: "2019-01-26T22:42:22.331805845+00:00"
+creator: [email protected]
+expression: "&result"
+source: crates/ra_hir/src/ty/tests.rs
+---
+[11; 80) '{     ...x)]; }': ()
+[21; 22) 'x': &&[unknown]
+[25; 32) 'unknown': &&[unknown]
+[42; 43) 'y': &&[unknown]
+[46; 53) 'unknown': &&[unknown]
+[59; 77) '[(x, y..., &x)]': [(&&[unknown], &&[unknown])]
+[60; 66) '(x, y)': (&&[unknown], &&[unknown])
+[61; 62) 'x': &&[unknown]
+[64; 65) 'y': &&[unknown]
+[68; 76) '(&y, &x)': (&&&[unknown], &&&[unknown])
+[69; 71) '&y': &&&[unknown]
+[70; 71) 'y': &&[unknown]
+[73; 75) '&x': &&&[unknown]
+[74; 75) 'x': &&[unknown]
+
diff --git a/crates/ra_hir/src/ty/tests.rs b/crates/ra_hir/src/ty/tests.rs
index e0b0689f8..f74d6f5ea 100644
--- a/crates/ra_hir/src/ty/tests.rs
+++ b/crates/ra_hir/src/ty/tests.rs
@@ -3,6 +3,7 @@ use std::fmt::Write;
 
 use ra_db::{SourceDatabase, salsa::Database};
 use ra_syntax::ast::{self, AstNode};
+use test_utils::covers;
 
 use crate::{
     source_binder,
@@ -285,6 +286,23 @@ fn test() {
 }
 
 #[test]
+fn infer_in_elseif() {
+    check_inference(
+        "infer_in_elseif",
+        r#"
+struct Foo { field: i32 }
+fn main(foo: Foo) {
+    if true {
+
+    } else if false {
+        foo.field
+    }
+}
+"#,
+    )
+}
+
+#[test]
 fn infer_inherent_method() {
     check_inference(
         "infer_inherent_method",
@@ -545,6 +563,37 @@ fn quux() {
     );
 }
 
+#[test]
+fn recursive_vars() {
+    covers!(type_var_cycles_resolve_completely);
+    covers!(type_var_cycles_resolve_as_possible);
+    check_inference(
+        "recursive_vars",
+        r#"
+fn test() {
+    let y = unknown;
+    [y, &y];
+}
+"#,
+    );
+}
+
+#[test]
+fn recursive_vars_2() {
+    covers!(type_var_cycles_resolve_completely);
+    covers!(type_var_cycles_resolve_as_possible);
+    check_inference(
+        "recursive_vars_2",
+        r#"
+fn test() {
+    let x = unknown;
+    let y = unknown;
+    [(x, y), (&y, &x)];
+}
+"#,
+    );
+}
+
 fn infer(content: &str) -> String {
     let (db, _, file_id) = MockDatabase::with_single_file(content);
     let source_file = db.parse(file_id);