Implement type inference for literals (WIP)

5 files changed, 139 insertions, 4 deletions

diff --git a/crates/ra_hir/src/expr.rs b/crates/ra_hir/src/expr.rs
index f0936e9f3..e07725d05 100644
--- a/crates/ra_hir/src/expr.rs
+++ b/crates/ra_hir/src/expr.rs
@@ -5,7 +5,10 @@ use rustc_hash::FxHashMap;
 
 use ra_arena::{Arena, RawId, impl_arena_id, map::ArenaMap};
 use ra_db::{LocalSyntaxPtr, Cancelable};
-use ra_syntax::ast::{self, AstNode, LoopBodyOwner, ArgListOwner, NameOwner};
+use ra_syntax::{
+    SyntaxKind,
+    ast::{self, AstNode, LoopBodyOwner, ArgListOwner, NameOwner}
+};
 
 use crate::{Path, type_ref::{Mutability, TypeRef}, Name, HirDatabase, DefId, Def, name::AsName};
 
@@ -104,6 +107,19 @@ impl BodySyntaxMapping {
 }
 
 #[derive(Debug, Clone, Eq, PartialEq)]
+pub enum Literal {
+    String(String),
+    ByteString(Vec<u8>),
+    Char(char),
+    Bool(bool),
+    Byte(u8),
+    Int, // this and float need additional information
+    Float,
+    Tuple { values: Vec<ExprId> },
+    Array { values: Vec<ExprId> },
+}
+
+#[derive(Debug, Clone, Eq, PartialEq)]
 pub enum Expr {
     /// This is produced if syntax tree does not have a required expression piece.
     Missing,
@@ -186,6 +202,7 @@ pub enum Expr {
     Tuple {
         exprs: Vec<ExprId>,
     },
+    Literal(Literal),
 }
 
 pub use ra_syntax::ast::PrefixOp as UnaryOp;
@@ -305,6 +322,20 @@ impl Expr {
                     f(*expr);
                 }
             }
+            Expr::Literal(l) => match l {
+                Literal::Array { values } | Literal::Tuple { values } => {
+                    for &val in values {
+                        f(val);
+                    }
+                }
+                Literal::String(..)
+                | Literal::ByteString(..)
+                | Literal::Byte(..)
+                | Literal::Bool(..)
+                | Literal::Char(..)
+                | Literal::Int
+                | Literal::Float => {}
+            },
         }
     }
 }
@@ -633,13 +664,56 @@ impl ExprCollector {
                 let exprs = e.exprs().map(|expr| self.collect_expr(expr)).collect();
                 self.alloc_expr(Expr::Tuple { exprs }, syntax_ptr)
             }
+            ast::ExprKind::Literal(e) => {
+                let child = e.syntax().children().next();
+
+                if let Some(c) = child {
+                    let lit = match c.kind() {
+                        SyntaxKind::INT_NUMBER => Literal::Int,
+                        SyntaxKind::FLOAT_NUMBER => Literal::Float,
+                        SyntaxKind::STRING => {
+                            // FIXME: this likely includes the " characters
+                            let text = c.text().to_string();
+                            Literal::String(text)
+                        }
+                        SyntaxKind::ARRAY_EXPR => {
+                            // TODO: recursively call to self
+                            Literal::Array { values: vec![] }
+                        }
+                        SyntaxKind::PAREN_EXPR => {
+                            // TODO: recursively call to self
+                            Literal::Tuple { values: vec![] }
+                        }
+                        SyntaxKind::TRUE_KW => Literal::Bool(true),
+                        SyntaxKind::FALSE_KW => Literal::Bool(false),
+                        SyntaxKind::BYTE_STRING => {
+                            // FIXME: this is completely incorrect for a variety
+                            // of reasons, but at least it gives the right type
+                            let bytes = c.text().to_string().into_bytes();
+                            Literal::ByteString(bytes)
+                        }
+                        SyntaxKind::CHAR => {
+                            let character = c.text().char_at(1).unwrap_or('X');
+                            Literal::Char(character)
+                        }
+                        SyntaxKind::BYTE => {
+                            let character = c.text().char_at(1).unwrap_or('X');
+                            Literal::Byte(character as u8)
+                        }
+                        _ => return self.alloc_expr(Expr::Missing, syntax_ptr),
+                    };
+
+                    self.alloc_expr(Expr::Literal(lit), syntax_ptr)
+                } else {
+                    self.alloc_expr(Expr::Missing, syntax_ptr)
+                }
+            }
 
             // TODO implement HIR for these:
             ast::ExprKind::Label(_e) => self.alloc_expr(Expr::Missing, syntax_ptr),
             ast::ExprKind::IndexExpr(_e) => self.alloc_expr(Expr::Missing, syntax_ptr),
             ast::ExprKind::ArrayExpr(_e) => self.alloc_expr(Expr::Missing, syntax_ptr),
             ast::ExprKind::RangeExpr(_e) => self.alloc_expr(Expr::Missing, syntax_ptr),
-            ast::ExprKind::Literal(_e) => self.alloc_expr(Expr::Missing, syntax_ptr),
         }
     }
 
diff --git a/crates/ra_hir/src/ty.rs b/crates/ra_hir/src/ty.rs
index fa46ddfe9..0baa205a1 100644
--- a/crates/ra_hir/src/ty.rs
+++ b/crates/ra_hir/src/ty.rs
@@ -38,7 +38,7 @@ use crate::{
     db::HirDatabase,
     type_ref::{TypeRef, Mutability},
     name::KnownName,
-    expr::{Body, Expr, ExprId, PatId, UnaryOp, BinaryOp, Statement},
+    expr::{Body, Expr, Literal, ExprId, PatId, UnaryOp, BinaryOp, Statement},
 };
 
 fn transpose<T>(x: Cancelable<Option<T>>) -> Option<Cancelable<T>> {
@@ -1067,6 +1067,37 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
 
                 Ty::Tuple(Arc::from(ty_vec))
             }
+            Expr::Literal(lit) => match lit {
+                Literal::Bool(..) => Ty::Bool,
+                Literal::String(..) => Ty::Ref(Arc::new(Ty::Str), Mutability::Shared),
+                Literal::ByteString(..) => {
+                    let byte_type = Arc::new(Ty::Uint(primitive::UintTy::U8));
+                    let slice_type = Arc::new(Ty::Slice(byte_type));
+                    Ty::Ref(slice_type, Mutability::Shared)
+                }
+                Literal::Byte(..) => Ty::Uint(primitive::UintTy::U8),
+                Literal::Char(..) => Ty::Char,
+                Literal::Tuple { values } => {
+                    let mut inner_tys = Vec::new();
+                    for &expr in values {
+                        let inner_ty = self.infer_expr(expr, &Expectation::none())?;
+                        inner_tys.push(inner_ty);
+                    }
+                    Ty::Tuple(Arc::from(inner_tys))
+                }
+                Literal::Array { values } => {
+                    // simply take the type of the first element for now
+                    let inner_ty = match values.get(0) {
+                        Some(&expr) => self.infer_expr(expr, &Expectation::none())?,
+                        None => Ty::Unknown,
+                    };
+                    // TODO: we should return a Ty::Array when it becomes
+                    // available
+                    Ty::Slice(Arc::new(inner_ty))
+                }
+                // TODO
+                Literal::Int | Literal::Float => Ty::Unknown,
+            },
         };
         // use a new type variable if we got Ty::Unknown here
         let ty = self.insert_type_vars_shallow(ty);
diff --git a/crates/ra_hir/src/ty/tests.rs b/crates/ra_hir/src/ty/tests.rs
index 920188fc9..97d3d222f 100644
--- a/crates/ra_hir/src/ty/tests.rs
+++ b/crates/ra_hir/src/ty/tests.rs
@@ -133,6 +133,26 @@ fn test(a: &u32, b: &mut u32, c: *const u32, d: *mut u32) {
 }
 
 #[test]
+fn infer_literals() {
+    check_inference(
+        r#"
+fn test() {
+    5i32;
+    "hello";
+    b"bytes";
+    'c';
+    b'b';
+    3.14;
+    5000;
+    (0u32, -5isize);
+    [true, true, false]
+}
+"#,
+        "literals.txt",
+    );
+}
+
+#[test]
 fn infer_backwards() {
     check_inference(
         r#"
diff --git a/crates/ra_hir/src/ty/tests/data/basics.txt b/crates/ra_hir/src/ty/tests/data/basics.txt
index ac7faae0a..e02947ba8 100644
--- a/crates/ra_hir/src/ty/tests/data/basics.txt
+++ b/crates/ra_hir/src/ty/tests/data/basics.txt
@@ -9,5 +9,5 @@
 [69; 70) 'd': &str
 [76; 82) '1usize': [unknown]
 [88; 94) '1isize': [unknown]
-[100; 106) '"test"': [unknown]
+[100; 106) '"test"': &str
 [112; 118) '1.0f32': [unknown]
diff --git a/crates/ra_hir/src/ty/tests/data/literals.txt b/crates/ra_hir/src/ty/tests/data/literals.txt
new file mode 100644
index 000000000..8b22eee31
--- /dev/null
+++ b/crates/ra_hir/src/ty/tests/data/literals.txt
@@ -0,0 +1,10 @@
+[11; 135) '{     ...lse] }': ()
+[17; 21) '5i32': [unknown]
+[27; 34) '"hello"': &str
+[40; 48) 'b"bytes"': &[u8]
+[54; 57) ''c'': char
+[63; 67) 'b'b'': u8
+[73; 77) '3.14': [unknown]
+[83; 87) '5000': [unknown]
+[93; 108) '(0u32, -5isize)': [unknown]
+[114; 133) '[true,...false]': ()