From 377fa7db3f1664dcc46213402b4fb7bd98923475 Mon Sep 17 00:00:00 2001 From: Lukas Wirth Date: Tue, 24 Nov 2020 18:28:55 +0100 Subject: Check structs for match exhaustiveness --- crates/hir_ty/src/diagnostics/match_check.rs | 151 +++++++++++++++++++++------ 1 file changed, 120 insertions(+), 31 deletions(-) (limited to 'crates/hir_ty') diff --git a/crates/hir_ty/src/diagnostics/match_check.rs b/crates/hir_ty/src/diagnostics/match_check.rs index a52f41764..62c329731 100644 --- a/crates/hir_ty/src/diagnostics/match_check.rs +++ b/crates/hir_ty/src/diagnostics/match_check.rs @@ -223,7 +223,7 @@ use hir_def::{ adt::VariantData, body::Body, expr::{Expr, Literal, Pat, PatId}, - AdtId, EnumVariantId, VariantId, + AdtId, EnumVariantId, StructId, VariantId, }; use smallvec::{smallvec, SmallVec}; @@ -391,21 +391,28 @@ impl PatStack { } } (Pat::Wild, constructor) => Some(self.expand_wildcard(cx, constructor)?), - (Pat::Path(_), Constructor::Enum(constructor)) => { + (Pat::Path(_), constructor) => { // unit enum variants become `Pat::Path` let pat_id = head.as_id().expect("we know this isn't a wild"); - if !enum_variant_matches(cx, pat_id, *constructor) { + let variant_id: VariantId = match constructor { + &Constructor::Enum(e) => e.into(), + &Constructor::Struct(s) => s.into(), + _ => return Err(MatchCheckErr::NotImplemented), + }; + if Some(variant_id) != cx.infer.variant_resolution_for_pat(pat_id) { None } else { Some(self.to_tail()) } } - ( - Pat::TupleStruct { args: ref pat_ids, ellipsis, .. }, - Constructor::Enum(enum_constructor), - ) => { + (Pat::TupleStruct { args: ref pat_ids, ellipsis, .. }, constructor) => { let pat_id = head.as_id().expect("we know this isn't a wild"); - if !enum_variant_matches(cx, pat_id, *enum_constructor) { + let variant_id: VariantId = match constructor { + &Constructor::Enum(e) => e.into(), + &Constructor::Struct(s) => s.into(), + _ => return Err(MatchCheckErr::MalformedMatchArm), + }; + if Some(variant_id) != cx.infer.variant_resolution_for_pat(pat_id) { None } else { let constructor_arity = constructor.arity(cx)?; @@ -443,12 +450,22 @@ impl PatStack { } } } - (Pat::Record { args: ref arg_patterns, .. }, Constructor::Enum(e)) => { + (Pat::Record { args: ref arg_patterns, .. }, constructor) => { let pat_id = head.as_id().expect("we know this isn't a wild"); - if !enum_variant_matches(cx, pat_id, *e) { + let (variant_id, variant_data) = match constructor { + &Constructor::Enum(e) => ( + e.into(), + cx.db.enum_data(e.parent).variants[e.local_id].variant_data.clone(), + ), + &Constructor::Struct(s) => { + (s.into(), cx.db.struct_data(s).variant_data.clone()) + } + _ => return Err(MatchCheckErr::MalformedMatchArm), + }; + if Some(variant_id) != cx.infer.variant_resolution_for_pat(pat_id) { None } else { - match cx.db.enum_data(e.parent).variants[e.local_id].variant_data.as_ref() { + match variant_data.as_ref() { VariantData::Record(struct_field_arena) => { // Here we treat any missing fields in the record as the wild pattern, as // if the record has ellipsis. We want to do this here even if the @@ -727,6 +744,7 @@ enum Constructor { Bool(bool), Tuple { arity: usize }, Enum(EnumVariantId), + Struct(StructId), } impl Constructor { @@ -741,6 +759,11 @@ impl Constructor { VariantData::Unit => 0, } } + &Constructor::Struct(s) => match cx.db.struct_data(s).variant_data.as_ref() { + VariantData::Tuple(struct_field_data) => struct_field_data.len(), + VariantData::Record(struct_field_data) => struct_field_data.len(), + VariantData::Unit => 0, + }, }; Ok(arity) @@ -749,7 +772,7 @@ impl Constructor { fn all_constructors(&self, cx: &MatchCheckCtx) -> Vec { match self { Constructor::Bool(_) => vec![Constructor::Bool(true), Constructor::Bool(false)], - Constructor::Tuple { .. } => vec![*self], + Constructor::Tuple { .. } | Constructor::Struct(_) => vec![*self], Constructor::Enum(e) => cx .db .enum_data(e.parent) @@ -786,6 +809,7 @@ fn pat_constructor(cx: &MatchCheckCtx, pat: PatIdOrWild) -> MatchCheckResult { Some(Constructor::Enum(enum_variant_id)) } + VariantId::StructId(struct_id) => Some(Constructor::Struct(struct_id)), _ => return Err(MatchCheckErr::NotImplemented), } } @@ -830,13 +854,13 @@ fn all_constructors_covered( false }), + &Constructor::Struct(s) => used_constructors.iter().any(|constructor| match constructor { + &Constructor::Struct(sid) => sid == s, + _ => false, + }), } } -fn enum_variant_matches(cx: &MatchCheckCtx, pat_id: PatId, enum_variant_id: EnumVariantId) -> bool { - Some(enum_variant_id.into()) == cx.infer.variant_resolution_for_pat(pat_id) -} - #[cfg(test)] mod tests { use crate::diagnostics::tests::check_diagnostics; @@ -848,8 +872,8 @@ mod tests { fn main() { match () { } //^^ Missing match arm - match (()) { } - //^^^^ Missing match arm + match (()) { } + //^^^^ Missing match arm match () { _ => (), } match () { () => (), } @@ -1393,6 +1417,84 @@ fn main() { ); } + #[test] + fn record_struct() { + check_diagnostics( + r#"struct Foo { a: bool } +fn main(f: Foo) { + match f {} + //^ Missing match arm + match f { Foo { a: true } => () } + //^ Missing match arm + match &f { Foo { a: true } => () } + //^^ Missing match arm + match f { Foo { a: _ } => () } + match f { + Foo { a: true } => (), + Foo { a: false } => (), + } + match &f { + Foo { a: true } => (), + Foo { a: false } => (), + } +} +"#, + ); + } + + #[test] + fn tuple_struct() { + check_diagnostics( + r#"struct Foo(bool); +fn main(f: Foo) { + match f {} + //^ Missing match arm + match f { Foo(true) => () } + //^ Missing match arm + match f { + Foo(true) => (), + Foo(false) => (), + } +} +"#, + ); + } + + #[test] + fn unit_struct() { + check_diagnostics( + r#"struct Foo; +fn main(f: Foo) { + match f {} + //^ Missing match arm + match f { Foo => () } +} +"#, + ); + } + + #[test] + fn record_struct_ellipsis() { + check_diagnostics( + r#"struct Foo { foo: bool, bar: bool } +fn main(f: Foo) { + match f { Foo { foo: true, .. } => () } + //^ Missing match arm + match f { + //^ Missing match arm + Foo { foo: true, .. } => (), + Foo { bar: false, .. } => () + } + match f { Foo { .. } => () } + match f { + Foo { foo: true, .. } => (), + Foo { foo: false, .. } => () + } +} +"#, + ); + } + mod false_negatives { //! The implementation of match checking here is a work in progress. As we roll this out, we //! prefer false negatives to false positives (ideally there would be no false positives). This @@ -1431,19 +1533,6 @@ fn main() { Either::A(true | false) => (), } } -"#, - ); - } - - #[test] - fn struct_missing_arm() { - // We don't currently handle structs. - check_diagnostics( - r#" -struct Foo { a: bool } -fn main(f: Foo) { - match f { Foo { a: true } => () } -} "#, ); } -- cgit v1.2.3