From e37b6c58378355347898cbdf1eef278137f6b461 Mon Sep 17 00:00:00 2001 From: Florian Diebold Date: Mon, 26 Aug 2019 20:12:41 +0200 Subject: Make infer_block not unify; add back calculate_least_upper_bound --- crates/ra_hir/src/ty/infer.rs | 74 +++++++++++++++++++++++++++++++------------ crates/ra_hir/src/ty/tests.rs | 22 +++++++------ 2 files changed, 66 insertions(+), 30 deletions(-) (limited to 'crates/ra_hir/src') diff --git a/crates/ra_hir/src/ty/infer.rs b/crates/ra_hir/src/ty/infer.rs index 074baa8ef..0aa993067 100644 --- a/crates/ra_hir/src/ty/infer.rs +++ b/crates/ra_hir/src/ty/infer.rs @@ -975,48 +975,44 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> { ret_ty } - fn coerce(&mut self, tgt_expr: ExprId, ty1: Ty, ty2: Ty) -> Ty { - if is_never(&ty1) { - ty2 + /// This is similar to unify, but it makes the first type coerce to the + /// second one. + fn coerce(&mut self, from_ty: &Ty, to_ty: &Ty) -> bool { + if is_never(from_ty) { + // ! coerces to any type + true } else { - self.unify(&ty1, &ty2); - // TODO Fugly and looks like we need more, `infer_adt_pattern` and other fails - let ty = self.resolve_ty_as_possible(&mut vec![], ty1); - self.write_expr_ty(tgt_expr, ty.clone()); - ty + self.unify(from_ty, to_ty) } } fn infer_expr(&mut self, tgt_expr: ExprId, expected: &Expectation) -> Ty { let ty = self.infer_expr_inner(tgt_expr, expected); - // use a new type variable if we got Ty::Unknown here - let ty = self.insert_type_vars_shallow(ty); let could_unify = self.unify(&ty, &expected.ty); - let ty = self.resolve_ty_as_possible(&mut vec![], ty); - self.write_expr_ty(tgt_expr, ty.clone()); if !could_unify { self.result.type_mismatches.insert( tgt_expr, TypeMismatch { expected: expected.ty.clone(), actual: ty.clone() }, ); } + let ty = self.resolve_ty_as_possible(&mut vec![], ty); ty } fn infer_expr_inner(&mut self, tgt_expr: ExprId, expected: &Expectation) -> Ty { let body = Arc::clone(&self.body); // avoid borrow checker problem - match &body[tgt_expr] { + let ty = match &body[tgt_expr] { Expr::Missing => Ty::Unknown, Expr::If { condition, then_branch, else_branch } => { // if let is desugared to match, so this is always simple if self.infer_expr(*condition, &Expectation::has_type(Ty::simple(TypeCtor::Bool))); let then_ty = self.infer_expr_inner(*then_branch, &expected); - self.coerce(*then_branch, then_ty.clone(), expected.ty.clone()); + self.coerce(&then_ty, &expected.ty); match else_branch { Some(else_branch) => { let else_ty = self.infer_expr_inner(*else_branch, &expected); - self.coerce(*else_branch, else_ty, expected.ty.clone()); + self.coerce(&else_ty, &expected.ty); } None => { // no else branch -> unit @@ -1111,6 +1107,8 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> { expected.clone() }; + let mut arm_tys = Vec::with_capacity(arms.len()); + for arm in arms { for &pat in &arm.pats { let _pat_ty = self.infer_pat(pat, &input_ty, BindingMode::default()); @@ -1121,11 +1119,16 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> { &Expectation::has_type(Ty::simple(TypeCtor::Bool)), ); } - let match_arm_ty = self.infer_expr_inner(arm.expr, &expected); - self.coerce(arm.expr, match_arm_ty, expected.ty.clone()); + arm_tys.push(self.infer_expr_inner(arm.expr, &expected)); } - expected.ty + let lub_ty = calculate_least_upper_bound(expected.ty.clone(), &arm_tys); + + for arm_ty in &arm_tys { + self.coerce(arm_ty, &lub_ty); + } + + lub_ty } Expr::Path(p) => { // FIXME this could be more efficient... @@ -1385,7 +1388,12 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> { Literal::Int(_v, ty) => Ty::simple(TypeCtor::Int(*ty)), Literal::Float(_v, ty) => Ty::simple(TypeCtor::Float(*ty)), }, - } + }; + // use a new type variable if we got Ty::Unknown here + let ty = self.insert_type_vars_shallow(ty); + let ty = self.resolve_ty_as_possible(&mut vec![], ty); + self.write_expr_ty(tgt_expr, ty.clone()); + ty } fn infer_block( @@ -1414,7 +1422,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> { } } } - let ty = if let Some(expr) = tail { self.infer_expr(expr, expected) } else { Ty::unit() }; + let ty = if let Some(expr) = tail { self.infer_expr_inner(expr, expected) } else { Ty::unit() }; ty } @@ -1644,3 +1652,29 @@ fn is_never(ty: &Ty) -> bool { false } } + +fn calculate_least_upper_bound(expected_ty: Ty, actual_tys: &[Ty]) -> Ty { + let mut all_never = true; + let mut last_never_ty = None; + let mut least_upper_bound = expected_ty; + + for actual_ty in actual_tys { + if is_never(actual_ty) { + last_never_ty = Some(actual_ty.clone()); + } else { + all_never = false; + least_upper_bound = match (actual_ty, &least_upper_bound) { + (_, Ty::Unknown) + | (Ty::Infer(_), Ty::Infer(InferTy::TypeVar(_))) + | (Ty::Apply(_), _) => actual_ty.clone(), + _ => least_upper_bound, + } + } + } + + if all_never && last_never_ty.is_some() { + last_never_ty.unwrap() + } else { + least_upper_bound + } +} diff --git a/crates/ra_hir/src/ty/tests.rs b/crates/ra_hir/src/ty/tests.rs index 4fa9d131d..7fc9fbb63 100644 --- a/crates/ra_hir/src/ty/tests.rs +++ b/crates/ra_hir/src/ty/tests.rs @@ -718,16 +718,18 @@ fn main(foo: Foo) { } "#), @r###" -[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"### + ⋮ + ⋮[35; 38) 'foo': Foo + ⋮[45; 109) '{ ... } }': () + ⋮[51; 107) 'if tru... }': () + ⋮[54; 58) 'true': bool + ⋮[59; 67) '{ }': () + ⋮[73; 107) 'if fal... }': () + ⋮[76; 81) 'false': bool + ⋮[82; 107) '{ ... }': i32 + ⋮[92; 95) 'foo': Foo + ⋮[92; 101) 'foo.field': i32 + "### ) } -- cgit v1.2.3