20 files changed, 384 insertions, 76 deletions

diff --git a/.gitignore b/.gitignore
index 872f72f16..99e0c5003 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,7 @@
 /target/
 crates/*/target
 **/*.rs.bk
+**/*.rs.pending-snap
 .idea/*
 *.log
 *.iml
diff --git a/crates/ra_hir/src/expr.rs b/crates/ra_hir/src/expr.rs
index b2a237ece..589a9b2db 100644
--- a/crates/ra_hir/src/expr.rs
+++ b/crates/ra_hir/src/expr.rs
@@ -6,7 +6,7 @@ use rustc_hash::FxHashMap;
 use ra_arena::{Arena, RawId, impl_arena_id, map::ArenaMap};
 use ra_syntax::{
     SyntaxNodePtr, AstPtr, AstNode,
-    ast::{self, LoopBodyOwner, ArgListOwner, NameOwner, LiteralKind, TypeAscriptionOwner}
+    ast::{self, LoopBodyOwner, ArgListOwner, NameOwner, LiteralKind,ArrayExprKind, TypeAscriptionOwner}
 };
 
 use crate::{
@@ -238,14 +238,17 @@ pub enum Expr {
     Tuple {
         exprs: Vec<ExprId>,
     },
-    Array {
-        exprs: Vec<ExprId>,
-    },
+    Array(Array),
     Literal(Literal),
 }
 
 pub use ra_syntax::ast::PrefixOp as UnaryOp;
 pub use ra_syntax::ast::BinOp as BinaryOp;
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub enum Array {
+    ElementList(Vec<ExprId>),
+    Repeat { initializer: ExprId, repeat: ExprId },
+}
 
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub struct MatchArm {
@@ -348,11 +351,22 @@ impl Expr {
             | Expr::UnaryOp { expr, .. } => {
                 f(*expr);
             }
-            Expr::Tuple { exprs } | Expr::Array { exprs } => {
+            Expr::Tuple { exprs } => {
                 for expr in exprs {
                     f(*expr);
                 }
             }
+            Expr::Array(a) => match a {
+                Array::ElementList(exprs) => {
+                    for expr in exprs {
+                        f(*expr);
+                    }
+                }
+                Array::Repeat { initializer, repeat } => {
+                    f(*initializer);
+                    f(*repeat)
+                }
+            },
             Expr::Literal(_) => {}
         }
     }
@@ -671,7 +685,10 @@ impl ExprCollector {
             }
             ast::ExprKind::FieldExpr(e) => {
                 let expr = self.collect_expr_opt(e.expr());
-                let name = e.name_ref().map(|nr| nr.as_name()).unwrap_or_else(Name::missing);
+                let name = match e.field_access() {
+                    Some(kind) => kind.as_name(),
+                    _ => Name::missing(),
+                };
                 self.alloc_expr(Expr::Field { expr, name }, syntax_ptr)
             }
             ast::ExprKind::TryExpr(e) => {
@@ -720,10 +737,26 @@ impl ExprCollector {
                 let exprs = e.exprs().map(|expr| self.collect_expr(expr)).collect();
                 self.alloc_expr(Expr::Tuple { exprs }, syntax_ptr)
             }
+
             ast::ExprKind::ArrayExpr(e) => {
-                let exprs = e.exprs().map(|expr| self.collect_expr(expr)).collect();
-                self.alloc_expr(Expr::Array { exprs }, syntax_ptr)
+                let kind = e.kind();
+
+                match kind {
+                    ArrayExprKind::ElementList(e) => {
+                        let exprs = e.map(|expr| self.collect_expr(expr)).collect();
+                        self.alloc_expr(Expr::Array(Array::ElementList(exprs)), syntax_ptr)
+                    }
+                    ArrayExprKind::Repeat { initializer, repeat } => {
+                        let initializer = self.collect_expr_opt(initializer);
+                        let repeat = self.collect_expr_opt(repeat);
+                        self.alloc_expr(
+                            Expr::Array(Array::Repeat { initializer, repeat }),
+                            syntax_ptr,
+                        )
+                    }
+                }
             }
+
             ast::ExprKind::Literal(e) => {
                 let lit = match e.kind() {
                     LiteralKind::IntNumber { suffix } => {
diff --git a/crates/ra_hir/src/name.rs b/crates/ra_hir/src/name.rs
index 677d18efc..283f37845 100644
--- a/crates/ra_hir/src/name.rs
+++ b/crates/ra_hir/src/name.rs
@@ -90,6 +90,15 @@ impl AsName for ast::Name {
     }
 }
 
+impl<'a> AsName for ast::FieldKind<'a> {
+    fn as_name(&self) -> Name {
+        match self {
+            ast::FieldKind::Name(nr) => nr.as_name(),
+            ast::FieldKind::Index(idx) => Name::new(idx.text().clone()),
+        }
+    }
+}
+
 impl AsName for ra_db::Dependency {
     fn as_name(&self) -> Name {
         Name::new(self.name.clone())
diff --git a/crates/ra_hir/src/ty.rs b/crates/ra_hir/src/ty.rs
index d42c61e9d..20e55d92d 100644
--- a/crates/ra_hir/src/ty.rs
+++ b/crates/ra_hir/src/ty.rs
@@ -353,10 +353,14 @@ impl HirDisplay for ApplicationTy {
             TypeCtor::Int(t) => write!(f, "{}", t)?,
             TypeCtor::Float(t) => write!(f, "{}", t)?,
             TypeCtor::Str => write!(f, "str")?,
-            TypeCtor::Slice | TypeCtor::Array => {
+            TypeCtor::Slice => {
                 let t = self.parameters.as_single();
                 write!(f, "[{}]", t.display(f.db))?;
             }
+            TypeCtor::Array => {
+                let t = self.parameters.as_single();
+                write!(f, "[{};_]", t.display(f.db))?;
+            }
             TypeCtor::RawPtr(m) => {
                 let t = self.parameters.as_single();
                 write!(f, "*{}{}", m.as_keyword_for_ptr(), t.display(f.db))?;
diff --git a/crates/ra_hir/src/ty/infer.rs b/crates/ra_hir/src/ty/infer.rs
index 887153484..28947be51 100644
--- a/crates/ra_hir/src/ty/infer.rs
+++ b/crates/ra_hir/src/ty/infer.rs
@@ -32,7 +32,7 @@ use crate::{
     DefWithBody,
     ImplItem,
     type_ref::{TypeRef, Mutability},
-    expr::{Body, Expr, BindingAnnotation, Literal, ExprId, Pat, PatId, UnaryOp, BinaryOp, Statement, FieldPat, self},
+    expr::{Body, Expr, BindingAnnotation, Literal, ExprId, Pat, PatId, UnaryOp, BinaryOp, Statement, FieldPat,Array, self},
     generics::GenericParams,
     path::{GenericArgs, GenericArg},
     adt::VariantDef,
@@ -489,8 +489,8 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 Some(ty)
             }
             Resolution::LocalBinding(pat) => {
-                let ty = self.type_of_pat.get(pat)?;
-                let ty = self.resolve_ty_as_possible(&mut vec![], ty.clone());
+                let ty = self.type_of_pat.get(pat)?.clone();
+                let ty = self.resolve_ty_as_possible(&mut vec![], ty);
                 Some(ty)
             }
             Resolution::GenericParam(..) => {
@@ -1074,7 +1074,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
 
                 Ty::apply(TypeCtor::Tuple, Substs(ty_vec.into()))
             }
-            Expr::Array { exprs } => {
+            Expr::Array(array) => {
                 let elem_ty = match &expected.ty {
                     Ty::Apply(a_ty) => match a_ty.ctor {
                         TypeCtor::Slice | TypeCtor::Array => {
@@ -1085,8 +1085,21 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                     _ => self.new_type_var(),
                 };
 
-                for expr in exprs.iter() {
-                    self.infer_expr(*expr, &Expectation::has_type(elem_ty.clone()));
+                match array {
+                    Array::ElementList(items) => {
+                        for expr in items.iter() {
+                            self.infer_expr(*expr, &Expectation::has_type(elem_ty.clone()));
+                        }
+                    }
+                    Array::Repeat { initializer, repeat } => {
+                        self.infer_expr(*initializer, &Expectation::has_type(elem_ty.clone()));
+                        self.infer_expr(
+                            *repeat,
+                            &Expectation::has_type(Ty::simple(TypeCtor::Int(
+                                primitive::UncertainIntTy::Known(primitive::IntTy::usize()),
+                            ))),
+                        );
+                    }
                 }
 
                 Ty::apply_one(TypeCtor::Array, elem_ty)
diff --git a/crates/ra_hir/src/ty/tests.rs b/crates/ra_hir/src/ty/tests.rs
index 0b7c841df..f6a325033 100644
--- a/crates/ra_hir/src/ty/tests.rs
+++ b/crates/ra_hir/src/ty/tests.rs
@@ -697,58 +697,58 @@ fn test(x: &str, y: isize) {
 [9; 10) 'x': &str
 [18; 19) 'y': isize
 [28; 324) '{     ... 3]; }': ()
-[38; 39) 'a': [&str]
-[42; 45) '[x]': [&str]
+[38; 39) 'a': [&str;_]
+[42; 45) '[x]': [&str;_]
 [43; 44) 'x': &str
-[55; 56) 'b': [[&str]]
-[59; 65) '[a, a]': [[&str]]
-[60; 61) 'a': [&str]
-[63; 64) 'a': [&str]
-[75; 76) 'c': [[[&str]]]
-[79; 85) '[b, b]': [[[&str]]]
-[80; 81) 'b': [[&str]]
-[83; 84) 'b': [[&str]]
-[96; 97) 'd': [isize]
-[100; 112) '[y, 1, 2, 3]': [isize]
+[55; 56) 'b': [[&str;_];_]
+[59; 65) '[a, a]': [[&str;_];_]
+[60; 61) 'a': [&str;_]
+[63; 64) 'a': [&str;_]
+[75; 76) 'c': [[[&str;_];_];_]
+[79; 85) '[b, b]': [[[&str;_];_];_]
+[80; 81) 'b': [[&str;_];_]
+[83; 84) 'b': [[&str;_];_]
+[96; 97) 'd': [isize;_]
+[100; 112) '[y, 1, 2, 3]': [isize;_]
 [101; 102) 'y': isize
 [104; 105) '1': isize
 [107; 108) '2': isize
 [110; 111) '3': isize
-[122; 123) 'd': [isize]
-[126; 138) '[1, y, 2, 3]': [isize]
+[122; 123) 'd': [isize;_]
+[126; 138) '[1, y, 2, 3]': [isize;_]
 [127; 128) '1': isize
 [130; 131) 'y': isize
 [133; 134) '2': isize
 [136; 137) '3': isize
-[148; 149) 'e': [isize]
-[152; 155) '[y]': [isize]
+[148; 149) 'e': [isize;_]
+[152; 155) '[y]': [isize;_]
 [153; 154) 'y': isize
-[165; 166) 'f': [[isize]]
-[169; 175) '[d, d]': [[isize]]
-[170; 171) 'd': [isize]
-[173; 174) 'd': [isize]
-[185; 186) 'g': [[isize]]
-[189; 195) '[e, e]': [[isize]]
-[190; 191) 'e': [isize]
-[193; 194) 'e': [isize]
-[206; 207) 'h': [i32]
-[210; 216) '[1, 2]': [i32]
+[165; 166) 'f': [[isize;_];_]
+[169; 175) '[d, d]': [[isize;_];_]
+[170; 171) 'd': [isize;_]
+[173; 174) 'd': [isize;_]
+[185; 186) 'g': [[isize;_];_]
+[189; 195) '[e, e]': [[isize;_];_]
+[190; 191) 'e': [isize;_]
+[193; 194) 'e': [isize;_]
+[206; 207) 'h': [i32;_]
+[210; 216) '[1, 2]': [i32;_]
 [211; 212) '1': i32
 [214; 215) '2': i32
-[226; 227) 'i': [&str]
-[230; 240) '["a", "b"]': [&str]
+[226; 227) 'i': [&str;_]
+[230; 240) '["a", "b"]': [&str;_]
 [231; 234) '"a"': &str
 [236; 239) '"b"': &str
-[251; 252) 'b': [[&str]]
-[255; 265) '[a, ["b"]]': [[&str]]
-[256; 257) 'a': [&str]
-[259; 264) '["b"]': [&str]
+[251; 252) 'b': [[&str;_];_]
+[255; 265) '[a, ["b"]]': [[&str;_];_]
+[256; 257) 'a': [&str;_]
+[259; 264) '["b"]': [&str;_]
 [260; 263) '"b"': &str
-[275; 276) 'x': [u8]
-[288; 290) '[]': [u8]
-[300; 301) 'z': &[u8]
-[311; 321) '&[1, 2, 3]': &[u8]
-[312; 321) '[1, 2, 3]': [u8]
+[275; 276) 'x': [u8;_]
+[288; 290) '[]': [u8;_]
+[300; 301) 'z': &[u8;_]
+[311; 321) '&[1, 2, 3]': &[u8;_]
+[312; 321) '[1, 2, 3]': [u8;_]
 [313; 314) '1': u8
 [316; 317) '2': u8
 [319; 320) '3': u8"###
@@ -1553,7 +1553,7 @@ fn test() {
 [11; 48) '{     ...&y]; }': ()
 [21; 22) 'y': &{unknown}
 [25; 32) 'unknown': &{unknown}
-[38; 45) '[y, &y]': [&&{unknown}]
+[38; 45) '[y, &y]': [&&{unknown};_]
 [39; 40) 'y': &{unknown}
 [42; 44) '&y': &&{unknown}
 [43; 44) 'y': &{unknown}"###
@@ -1578,7 +1578,7 @@ fn test() {
 [25; 32) 'unknown': &&{unknown}
 [42; 43) 'y': &&{unknown}
 [46; 53) 'unknown': &&{unknown}
-[59; 77) '[(x, y..., &x)]': [(&&{unknown}, &&{unknown})]
+[59; 77) '[(x, y..., &x)]': [(&&{unknown}, &&{unknown});_]
 [60; 66) '(x, y)': (&&{unknown}, &&{unknown})
 [61; 62) 'x': &&{unknown}
 [64; 65) 'y': &&{unknown}
@@ -1670,8 +1670,8 @@ fn test_line_buffer() {
 "#),
         @r###"
 [23; 53) '{     ...n']; }': ()
-[29; 50) '&[0, b...b'\n']': &[u8]
-[30; 50) '[0, b'...b'\n']': [u8]
+[29; 50) '&[0, b...b'\n']': &[u8;_]
+[30; 50) '[0, b'...b'\n']': [u8;_]
 [31; 32) '0': u8
 [34; 39) 'b'\n'': u8
 [41; 42) '1': u8
@@ -2242,6 +2242,65 @@ static B: u64 = { let x = 1; x };
     );
 }
 
+#[test]
+fn tuple_struct_fields() {
+    assert_snapshot_matches!(
+        infer(r#"
+struct S(i32, u64);
+fn test() -> u64 {
+    let a = S(4, 6);
+    let b = a.0;
+    a.1
+}
+"#),
+        @r###"
+[38; 87) '{     ... a.1 }': u64
+[48; 49) 'a': S
+[52; 53) 'S': S(i32, u64) -> S
+[52; 59) 'S(4, 6)': S
+[54; 55) '4': i32
+[57; 58) '6': u64
+[69; 70) 'b': i32
+[73; 74) 'a': S
+[73; 76) 'a.0': i32
+[82; 83) 'a': S
+[82; 85) 'a.1': u64"###
+    );
+}
+
+#[test]
+fn tuple_struct_with_fn() {
+    assert_snapshot_matches!(
+        infer(r#"
+struct S(fn(u32) -> u64);
+fn test() -> u64 {
+    let a = S(|i| 2*i);
+    let b = a.0(4);
+    a.0(2)
+}
+"#),
+        @r###"
+[44; 102) '{     ...0(2) }': u64
+[54; 55) 'a': S
+[58; 59) 'S': S(fn(u32) -> u64) -> S
+[58; 68) 'S(|i| 2*i)': S
+[60; 67) '|i| 2*i': fn(u32) -> u64
+[61; 62) 'i': i32
+[64; 65) '2': i32
+[64; 67) '2*i': i32
+[66; 67) 'i': i32
+[78; 79) 'b': u64
+[82; 83) 'a': S
+[82; 85) 'a.0': fn(u32) -> u64
+[82; 88) 'a.0(4)': u64
+[86; 87) '4': u32
+[94; 95) 'a': S
+[94; 97) 'a.0': fn(u32) -> u64
+[94; 100) 'a.0(2)': u64
+[98; 99) '2': u32"###
+    );
+}
+
 fn type_at_pos(db: &MockDatabase, pos: FilePosition) -> String {
     let func = source_binder::function_from_position(db, pos).unwrap();
     let body_source_map = func.body_source_map(db);
diff --git a/crates/ra_ide_api/src/completion/complete_dot.rs b/crates/ra_ide_api/src/completion/complete_dot.rs
index f54a02d1d..18b2d68d5 100644
--- a/crates/ra_ide_api/src/completion/complete_dot.rs
+++ b/crates/ra_ide_api/src/completion/complete_dot.rs
@@ -184,4 +184,26 @@ mod tests {
             ",
         );
     }
+
+    #[test]
+    fn test_tuple_field_inference() {
+        check_ref_completion(
+            "tuple_field_inference",
+            r"
+            pub struct S;
+            impl S {
+                pub fn blah(&self) {}
+            }
+
+            struct T(S);
+
+            impl T {
+                fn foo(&self) {
+                    // FIXME: This doesn't work without the trailing `a` as `0.` is a float
+                    self.0.a<|>
+                }
+            }
+            ",
+        );
+    }
 }
diff --git a/crates/ra_ide_api/src/completion/snapshots/completion_item__tuple_field_inference.snap b/crates/ra_ide_api/src/completion/snapshots/completion_item__tuple_field_inference.snap
new file mode 100644
index 000000000..72c8973b8
--- /dev/null
+++ b/crates/ra_ide_api/src/completion/snapshots/completion_item__tuple_field_inference.snap
@@ -0,0 +1,16 @@
+---
+created: "2019-04-05T23:00:18.283812700Z"
+creator: [email protected]
+source: crates/ra_ide_api/src/completion/completion_item.rs
+expression: kind_completions
+---
+[
+    CompletionItem {
+        label: "blah",
+        source_range: [299; 300),
+        delete: [299; 300),
+        insert: "blah()$0",
+        kind: Method,
+        detail: "pub fn blah(&self)"
+    }
+]
diff --git a/crates/ra_lsp_server/src/server_world.rs b/crates/ra_lsp_server/src/server_world.rs
index af4798494..4b1d592bb 100644
--- a/crates/ra_lsp_server/src/server_world.rs
+++ b/crates/ra_lsp_server/src/server_world.rs
@@ -11,12 +11,14 @@ use ra_ide_api::{
 use ra_vfs::{Vfs, VfsChange, VfsFile, VfsRoot};
 use relative_path::RelativePathBuf;
 use parking_lot::RwLock;
-use failure::format_err;
+use failure::{Error, format_err};
+use gen_lsp_server::ErrorCode;
 
 use crate::{
     project_model::ProjectWorkspace,
     vfs_filter::IncludeRustFiles,
     Result,
+    LspError,
 };
 
 #[derive(Debug)]
@@ -152,11 +154,13 @@ impl ServerWorld {
 
     pub fn uri_to_file_id(&self, uri: &Url) -> Result<FileId> {
         let path = uri.to_file_path().map_err(|()| format_err!("invalid uri: {}", uri))?;
-        let file = self
-            .vfs
-            .read()
-            .path2file(&path)
-            .ok_or_else(|| format_err!("unknown file: {}", path.display()))?;
+        let file = self.vfs.read().path2file(&path).ok_or_else(|| {
+            // Show warning as this file is outside current workspace
+            Error::from(LspError {
+                code: ErrorCode::InvalidRequest as i32,
+                message: "Rust file outside current workspace is not supported yet.".to_string(),
+            })
+        })?;
         Ok(FileId(file.0.into()))
     }
 
diff --git a/crates/ra_parser/src/grammar/expressions.rs b/crates/ra_parser/src/grammar/expressions.rs
index bf5d6544d..9b38b0a31 100644
--- a/crates/ra_parser/src/grammar/expressions.rs
+++ b/crates/ra_parser/src/grammar/expressions.rs
@@ -379,6 +379,14 @@ fn method_call_expr(p: &mut Parser, lhs: CompletedMarker) -> CompletedMarker {
 // fn foo() {
 //     x.foo;
 //     x.0.bar;
+//     x.0();
+// }
+
+// test_err bad_tuple_index_expr
+// fn foo() {
+//     x.0.;
+//     x.1i32;
+//     x.0x01;
 // }
 fn field_expr(p: &mut Parser, lhs: CompletedMarker) -> CompletedMarker {
     assert!(p.at(DOT));
@@ -387,7 +395,10 @@ fn field_expr(p: &mut Parser, lhs: CompletedMarker) -> CompletedMarker {
     if p.at(IDENT) {
         name_ref(p)
     } else if p.at(INT_NUMBER) {
-        p.bump()
+        p.bump();
+    } else if p.at(FLOAT_NUMBER) {
+        // FIXME: How to recover and instead parse INT + DOT?
+        p.bump();
     } else {
         p.error("expected field name or number")
     }
diff --git a/crates/ra_syntax/src/ast.rs b/crates/ra_syntax/src/ast.rs
index 9f5c41b0c..c2ab19d97 100644
--- a/crates/ra_syntax/src/ast.rs
+++ b/crates/ra_syntax/src/ast.rs
@@ -17,8 +17,8 @@ pub use self::{
     generated::*,
     traits::*,
     tokens::*,
-    extensions::{PathSegmentKind, StructKind, SelfParamKind},
-    expr_extensions::{ElseBranch, PrefixOp, BinOp, LiteralKind},
+    extensions::{PathSegmentKind, StructKind,FieldKind, SelfParamKind},
+    expr_extensions::{ElseBranch, PrefixOp, BinOp, LiteralKind,ArrayExprKind},
 };
 
 /// The main trait to go from untyped `SyntaxNode`  to a typed ast. The
diff --git a/crates/ra_syntax/src/ast/expr_extensions.rs b/crates/ra_syntax/src/ast/expr_extensions.rs
index 1d8313810..9484c3b9b 100644
--- a/crates/ra_syntax/src/ast/expr_extensions.rs
+++ b/crates/ra_syntax/src/ast/expr_extensions.rs
@@ -193,6 +193,28 @@ impl ast::BinExpr {
     }
 }
 
+pub enum ArrayExprKind<'a> {
+    Repeat { initializer: Option<&'a ast::Expr>, repeat: Option<&'a ast::Expr> },
+    ElementList(AstChildren<'a, ast::Expr>),
+}
+
+impl ast::ArrayExpr {
+    pub fn kind(&self) -> ArrayExprKind {
+        if self.is_repeat() {
+            ArrayExprKind::Repeat {
+                initializer: children(self).nth(0),
+                repeat: children(self).nth(1),
+            }
+        } else {
+            ArrayExprKind::ElementList(children(self))
+        }
+    }
+
+    fn is_repeat(&self) -> bool {
+        self.syntax().children_with_tokens().any(|it| it.kind() == SEMI)
+    }
+}
+
 #[derive(Clone, Debug, PartialEq, Eq, Hash)]
 pub enum LiteralKind {
     String,
diff --git a/crates/ra_syntax/src/ast/extensions.rs b/crates/ra_syntax/src/ast/extensions.rs
index aec57c380..ca33b43e7 100644
--- a/crates/ra_syntax/src/ast/extensions.rs
+++ b/crates/ra_syntax/src/ast/extensions.rs
@@ -3,11 +3,8 @@
 
 use itertools::Itertools;
 
-use crate::{
-    SmolStr, SyntaxToken,
-    ast::{self, AstNode, children, child_opt},
-    SyntaxKind::*,
-};
+use crate::{SmolStr, SyntaxToken, ast::{self, AstNode, children, child_opt}, SyntaxKind::*, SyntaxElement};
+use ra_parser::SyntaxKind;
 
 impl ast::Name {
     pub fn text(&self) -> &SmolStr {
@@ -217,6 +214,33 @@ impl ast::ExprStmt {
     }
 }
 
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum FieldKind<'a> {
+    Name(&'a ast::NameRef),
+    Index(SyntaxToken<'a>),
+}
+
+impl ast::FieldExpr {
+    pub fn index_token(&self) -> Option<SyntaxToken> {
+        self.syntax
+            .children_with_tokens()
+            // FIXME: Accepting floats here to reject them in validation later
+            .find(|c| c.kind() == SyntaxKind::INT_NUMBER || c.kind() == SyntaxKind::FLOAT_NUMBER)
+            .as_ref()
+            .and_then(SyntaxElement::as_token)
+    }
+
+    pub fn field_access(&self) -> Option<FieldKind> {
+        if let Some(nr) = self.name_ref() {
+            Some(FieldKind::Name(nr))
+        } else if let Some(tok) = self.index_token() {
+            Some(FieldKind::Index(tok))
+        } else {
+            None
+        }
+    }
+}
+
 impl ast::RefPat {
     pub fn is_mut(&self) -> bool {
         self.syntax().children_with_tokens().any(|n| n.kind() == MUT_KW)
diff --git a/crates/ra_syntax/src/syntax_error.rs b/crates/ra_syntax/src/syntax_error.rs
index 4b8c22a57..4198eefdb 100644
--- a/crates/ra_syntax/src/syntax_error.rs
+++ b/crates/ra_syntax/src/syntax_error.rs
@@ -95,6 +95,7 @@ pub enum SyntaxErrorKind {
     InvalidSuffix,
     InvalidBlockAttr,
     InvalidMatchInnerAttr,
+    InvalidTupleIndexFormat,
 }
 
 impl fmt::Display for SyntaxErrorKind {
@@ -139,6 +140,9 @@ impl fmt::Display for SyntaxErrorKind {
             InvalidMatchInnerAttr => {
                 write!(f, "Inner attributes are only allowed directly after the opening brace of the match expression")
             }
+            InvalidTupleIndexFormat => {
+                write!(f, "Tuple (struct) field access is only allowed through decimal integers with no underscores or suffix")
+            }
             ParseError(msg) => write!(f, "{}", msg.0),
         }
     }
diff --git a/crates/ra_syntax/src/validation.rs b/crates/ra_syntax/src/validation.rs
index fc534df83..c2f545173 100644
--- a/crates/ra_syntax/src/validation.rs
+++ b/crates/ra_syntax/src/validation.rs
@@ -3,6 +3,7 @@ mod byte_string;
 mod char;
 mod string;
 mod block;
+mod field_expr;
 
 use crate::{
     SourceFile, SyntaxError, AstNode, SyntaxNode,
@@ -17,6 +18,7 @@ pub(crate) fn validate(file: &SourceFile) -> Vec<SyntaxError> {
         let _ = visitor_ctx(&mut errors)
             .visit::<ast::Literal, _>(validate_literal)
             .visit::<ast::Block, _>(block::validate_block_node)
+            .visit::<ast::FieldExpr, _>(field_expr::validate_field_expr_node)
             .accept(node);
     }
     errors
diff --git a/crates/ra_syntax/src/validation/field_expr.rs b/crates/ra_syntax/src/validation/field_expr.rs
new file mode 100644
index 000000000..2b405062e
--- /dev/null
+++ b/crates/ra_syntax/src/validation/field_expr.rs
@@ -0,0 +1,12 @@
+use crate::{ast::{self, FieldKind},

+            SyntaxError,

+            SyntaxErrorKind::*,

+};

+

+pub(crate) fn validate_field_expr_node(node: &ast::FieldExpr, errors: &mut Vec<SyntaxError>) {

+    if let Some(FieldKind::Index(idx)) = node.field_access() {

+        if idx.text().chars().any(|c| c < '0' || c > '9') {

+            errors.push(SyntaxError::new(InvalidTupleIndexFormat, idx.range()));

+        }

+    }

+}

diff --git a/crates/ra_syntax/tests/data/parser/inline/err/0010_bad_tuple_index_expr.rs b/crates/ra_syntax/tests/data/parser/inline/err/0010_bad_tuple_index_expr.rs
new file mode 100644
index 000000000..30cc49138
--- /dev/null
+++ b/crates/ra_syntax/tests/data/parser/inline/err/0010_bad_tuple_index_expr.rs
@@ -0,0 +1,5 @@
+fn foo() {
+    x.0.;
+    x.1i32;
+    x.0x01;
+}
diff --git a/crates/ra_syntax/tests/data/parser/inline/err/0010_bad_tuple_index_expr.txt b/crates/ra_syntax/tests/data/parser/inline/err/0010_bad_tuple_index_expr.txt
new file mode 100644
index 000000000..c111f60ea
--- /dev/null
+++ b/crates/ra_syntax/tests/data/parser/inline/err/0010_bad_tuple_index_expr.txt
@@ -0,0 +1,51 @@
+SOURCE_FILE@[0; 47)
+  FN_DEF@[0; 46)
+    FN_KW@[0; 2) "fn"
+    WHITESPACE@[2; 3) " "
+    NAME@[3; 6)
+      IDENT@[3; 6) "foo"
+    PARAM_LIST@[6; 8)
+      L_PAREN@[6; 7) "("
+      R_PAREN@[7; 8) ")"
+    WHITESPACE@[8; 9) " "
+    BLOCK@[9; 46)
+      L_CURLY@[9; 10) "{"
+      WHITESPACE@[10; 15) "\n    "
+      EXPR_STMT@[15; 20)
+        FIELD_EXPR@[15; 19)
+          PATH_EXPR@[15; 16)
+            PATH@[15; 16)
+              PATH_SEGMENT@[15; 16)
+                NAME_REF@[15; 16)
+                  IDENT@[15; 16) "x"
+          DOT@[16; 17) "."
+          err: `Tuple (struct) field access is only allowed through decimal integers with no underscores or suffix`
+          FLOAT_NUMBER@[17; 19) "0."
+        SEMI@[19; 20) ";"
+      WHITESPACE@[20; 25) "\n    "
+      EXPR_STMT@[25; 32)
+        FIELD_EXPR@[25; 31)
+          PATH_EXPR@[25; 26)
+            PATH@[25; 26)
+              PATH_SEGMENT@[25; 26)
+                NAME_REF@[25; 26)
+                  IDENT@[25; 26) "x"
+          DOT@[26; 27) "."
+          err: `Tuple (struct) field access is only allowed through decimal integers with no underscores or suffix`
+          INT_NUMBER@[27; 31) "1i32"
+        SEMI@[31; 32) ";"
+      WHITESPACE@[32; 37) "\n    "
+      EXPR_STMT@[37; 44)
+        FIELD_EXPR@[37; 43)
+          PATH_EXPR@[37; 38)
+            PATH@[37; 38)
+              PATH_SEGMENT@[37; 38)
+                NAME_REF@[37; 38)
+                  IDENT@[37; 38) "x"
+          DOT@[38; 39) "."
+          err: `Tuple (struct) field access is only allowed through decimal integers with no underscores or suffix`
+          INT_NUMBER@[39; 43) "0x01"
+        SEMI@[43; 44) ";"
+      WHITESPACE@[44; 45) "\n"
+      R_CURLY@[45; 46) "}"
+  WHITESPACE@[46; 47) "\n"
diff --git a/crates/ra_syntax/tests/data/parser/inline/ok/0011_field_expr.rs b/crates/ra_syntax/tests/data/parser/inline/ok/0011_field_expr.rs
index 3e69538e5..b8da2ddc3 100644
--- a/crates/ra_syntax/tests/data/parser/inline/ok/0011_field_expr.rs
+++ b/crates/ra_syntax/tests/data/parser/inline/ok/0011_field_expr.rs
@@ -1,4 +1,5 @@
 fn foo() {
     x.foo;
     x.0.bar;
+    x.0();
 }
diff --git a/crates/ra_syntax/tests/data/parser/inline/ok/0011_field_expr.txt b/crates/ra_syntax/tests/data/parser/inline/ok/0011_field_expr.txt
index a86702843..78054ec5a 100644
--- a/crates/ra_syntax/tests/data/parser/inline/ok/0011_field_expr.txt
+++ b/crates/ra_syntax/tests/data/parser/inline/ok/0011_field_expr.txt
@@ -1,5 +1,5 @@
-SOURCE_FILE@[0; 37)
-  FN_DEF@[0; 36)
+SOURCE_FILE@[0; 48)
+  FN_DEF@[0; 47)
     FN_KW@[0; 2) "fn"
     WHITESPACE@[2; 3) " "
     NAME@[3; 6)
@@ -8,7 +8,7 @@ SOURCE_FILE@[0; 37)
       L_PAREN@[6; 7) "("
       R_PAREN@[7; 8) ")"
     WHITESPACE@[8; 9) " "
-    BLOCK@[9; 36)
+    BLOCK@[9; 47)
       L_CURLY@[9; 10) "{"
       WHITESPACE@[10; 15) "\n    "
       EXPR_STMT@[15; 21)
@@ -37,6 +37,21 @@ SOURCE_FILE@[0; 37)
           NAME_REF@[30; 33)
             IDENT@[30; 33) "bar"
         SEMI@[33; 34) ";"
-      WHITESPACE@[34; 35) "\n"
-      R_CURLY@[35; 36) "}"
-  WHITESPACE@[36; 37) "\n"
+      WHITESPACE@[34; 39) "\n    "
+      EXPR_STMT@[39; 45)
+        CALL_EXPR@[39; 44)
+          FIELD_EXPR@[39; 42)
+            PATH_EXPR@[39; 40)
+              PATH@[39; 40)
+                PATH_SEGMENT@[39; 40)
+                  NAME_REF@[39; 40)
+                    IDENT@[39; 40) "x"
+            DOT@[40; 41) "."
+            INT_NUMBER@[41; 42) "0"
+          ARG_LIST@[42; 44)
+            L_PAREN@[42; 43) "("
+            R_PAREN@[43; 44) ")"
+        SEMI@[44; 45) ";"
+      WHITESPACE@[45; 46) "\n"
+      R_CURLY@[46; 47) "}"
+  WHITESPACE@[47; 48) "\n"