Implement type inference for boolean operators

3 files changed, 38 insertions, 2 deletions

diff --git a/crates/ra_hir/src/ty.rs b/crates/ra_hir/src/ty.rs
index e33762e0d..718e193f7 100644
--- a/crates/ra_hir/src/ty.rs
+++ b/crates/ra_hir/src/ty.rs
@@ -26,7 +26,7 @@ use ena::unify::{InPlaceUnificationTable, UnifyKey, UnifyValue, NoError};
 
 use ra_db::{LocalSyntaxPtr, Cancelable};
 use ra_syntax::{
-    ast::{self, AstNode, LoopBodyOwner, ArgListOwner, PrefixOp},
+    ast::{self, AstNode, LoopBodyOwner, ArgListOwner, PrefixOp, BinOp},
     SyntaxNodeRef
 };
 
@@ -906,7 +906,16 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 }
             }
             ast::Expr::RangeExpr(_e) => Ty::Unknown,
-            ast::Expr::BinExpr(_e) => Ty::Unknown,
+            ast::Expr::BinExpr(e) => match e.op() {
+                Some(BinOp::BooleanOr)
+                | Some(BinOp::BooleanAnd)
+                | Some(BinOp::EqualityTest)
+                | Some(BinOp::LesserEqualTest)
+                | Some(BinOp::GreaterEqualTest)
+                | Some(BinOp::LesserTest)
+                | Some(BinOp::GreaterTest) => Ty::Bool,
+                _ => Ty::Unknown,
+            },
             ast::Expr::Literal(_e) => Ty::Unknown,
         };
         // use a new type variable if we got Ty::Unknown here
diff --git a/crates/ra_hir/src/ty/tests.rs b/crates/ra_hir/src/ty/tests.rs
index fb53fcf0b..97c466890 100644
--- a/crates/ra_hir/src/ty/tests.rs
+++ b/crates/ra_hir/src/ty/tests.rs
@@ -153,6 +153,23 @@ impl S {
     );
 }
 
+#[test]
+fn infer_boolean_op() {
+    check_inference(
+        r#"
+fn test() {
+    let x = a && b;
+    let y = true || false;
+    let z = x == y;
+    let h = CONST_1 <= CONST_2;
+
+    10 < 3
+}
+"#,
+        "0008_boolean_op.txt",
+    );
+}
+
 fn infer(content: &str) -> String {
     let (db, _, file_id) = MockDatabase::with_single_file(content);
     let source_file = db.source_file(file_id);
diff --git a/crates/ra_hir/src/ty/tests/data/0008_boolean_op.txt b/crates/ra_hir/src/ty/tests/data/0008_boolean_op.txt
new file mode 100644
index 000000000..cc07cdccb
--- /dev/null
+++ b/crates/ra_hir/src/ty/tests/data/0008_boolean_op.txt
@@ -0,0 +1,10 @@
+[21; 22) 'x': bool
+[68; 69) 'z': bool
+[72; 78) 'x == y': bool
+[45; 58) 'true || false': bool
+[11; 125) '{     ... < 3 }': bool
+[117; 123) '10 < 3': bool
+[88; 89) 'h': bool
+[41; 42) 'y': bool
+[92; 110) 'CONST_...ONST_2': bool
+[25; 31) 'a && b': bool