rust-analyzer/crates/hir_ty/src/diagnostics/expr.rs
2021-06-01 01:44:51 +05:00

822 lines
25 KiB
Rust

//! Various diagnostics for expressions that are collected together in one pass
//! through the body using inference results: mismatched arg counts, missing
//! fields, etc.
use std::{cell::RefCell, sync::Arc};
use hir_def::{
expr::Statement, path::path, resolver::HasResolver, AssocItemId, DefWithBodyId, HasModule,
};
use hir_expand::name;
use rustc_hash::FxHashSet;
use syntax::{ast, AstPtr};
use crate::{
db::HirDatabase,
diagnostics::{
match_check::{
self,
usefulness::{compute_match_usefulness, expand_pattern, MatchCheckCtx, PatternArena},
},
MismatchedArgCount, MissingFields, MissingMatchArms, MissingOkOrSomeInTailExpr,
MissingPatFields, RemoveThisSemicolon,
},
diagnostics_sink::DiagnosticSink,
AdtId, InferenceResult, Interner, TyExt, TyKind,
};
pub(crate) use hir_def::{
body::{Body, BodySourceMap},
expr::{Expr, ExprId, MatchArm, Pat, PatId},
LocalFieldId, VariantId,
};
use super::ReplaceFilterMapNextWithFindMap;
pub(super) struct ExprValidator<'a, 'b: 'a> {
owner: DefWithBodyId,
infer: Arc<InferenceResult>,
sink: &'a mut DiagnosticSink<'b>,
}
impl<'a, 'b> ExprValidator<'a, 'b> {
pub(super) fn new(
owner: DefWithBodyId,
infer: Arc<InferenceResult>,
sink: &'a mut DiagnosticSink<'b>,
) -> ExprValidator<'a, 'b> {
ExprValidator { owner, infer, sink }
}
pub(super) fn validate_body(&mut self, db: &dyn HirDatabase) {
self.check_for_filter_map_next(db);
let body = db.body(self.owner);
for (id, expr) in body.exprs.iter() {
if let Some((variant_def, missed_fields, true)) =
record_literal_missing_fields(db, &self.infer, id, expr)
{
self.create_record_literal_missing_fields_diagnostic(
id,
db,
variant_def,
missed_fields,
);
}
match expr {
Expr::Match { expr, arms } => {
self.validate_match(id, *expr, arms, db, self.infer.clone());
}
Expr::Call { .. } | Expr::MethodCall { .. } => {
self.validate_call(db, id, expr);
}
_ => {}
}
}
for (id, pat) in body.pats.iter() {
if let Some((variant_def, missed_fields, true)) =
record_pattern_missing_fields(db, &self.infer, id, pat)
{
self.create_record_pattern_missing_fields_diagnostic(
id,
db,
variant_def,
missed_fields,
);
}
}
let body_expr = &body[body.body_expr];
if let Expr::Block { statements, tail, .. } = body_expr {
if let Some(t) = tail {
self.validate_results_in_tail_expr(body.body_expr, *t, db);
} else if let Some(Statement::Expr { expr: id, .. }) = statements.last() {
self.validate_missing_tail_expr(body.body_expr, *id, db);
}
}
}
fn create_record_literal_missing_fields_diagnostic(
&mut self,
id: ExprId,
db: &dyn HirDatabase,
variant_def: VariantId,
missed_fields: Vec<LocalFieldId>,
) {
// XXX: only look at source_map if we do have missing fields
let (_, source_map) = db.body_with_source_map(self.owner);
if let Ok(source_ptr) = source_map.expr_syntax(id) {
let root = source_ptr.file_syntax(db.upcast());
if let ast::Expr::RecordExpr(record_expr) = &source_ptr.value.to_node(&root) {
if let Some(_) = record_expr.record_expr_field_list() {
let variant_data = variant_def.variant_data(db.upcast());
let missed_fields = missed_fields
.into_iter()
.map(|idx| variant_data.fields()[idx].name.clone())
.collect();
self.sink.push(MissingFields {
file: source_ptr.file_id,
field_list_parent: AstPtr::new(&record_expr),
field_list_parent_path: record_expr.path().map(|path| AstPtr::new(&path)),
missed_fields,
})
}
}
}
}
fn create_record_pattern_missing_fields_diagnostic(
&mut self,
id: PatId,
db: &dyn HirDatabase,
variant_def: VariantId,
missed_fields: Vec<LocalFieldId>,
) {
// XXX: only look at source_map if we do have missing fields
let (_, source_map) = db.body_with_source_map(self.owner);
if let Ok(source_ptr) = source_map.pat_syntax(id) {
if let Some(expr) = source_ptr.value.as_ref().left() {
let root = source_ptr.file_syntax(db.upcast());
if let ast::Pat::RecordPat(record_pat) = expr.to_node(&root) {
if let Some(_) = record_pat.record_pat_field_list() {
let variant_data = variant_def.variant_data(db.upcast());
let missed_fields = missed_fields
.into_iter()
.map(|idx| variant_data.fields()[idx].name.clone())
.collect();
self.sink.push(MissingPatFields {
file: source_ptr.file_id,
field_list_parent: AstPtr::new(&record_pat),
field_list_parent_path: record_pat
.path()
.map(|path| AstPtr::new(&path)),
missed_fields,
})
}
}
}
}
}
fn check_for_filter_map_next(&mut self, db: &dyn HirDatabase) {
// Find the FunctionIds for Iterator::filter_map and Iterator::next
let iterator_path = path![core::iter::Iterator];
let resolver = self.owner.resolver(db.upcast());
let iterator_trait_id = match resolver.resolve_known_trait(db.upcast(), &iterator_path) {
Some(id) => id,
None => return,
};
let iterator_trait_items = &db.trait_data(iterator_trait_id).items;
let filter_map_function_id =
match iterator_trait_items.iter().find(|item| item.0 == name![filter_map]) {
Some((_, AssocItemId::FunctionId(id))) => id,
_ => return,
};
let next_function_id = match iterator_trait_items.iter().find(|item| item.0 == name![next])
{
Some((_, AssocItemId::FunctionId(id))) => id,
_ => return,
};
// Search function body for instances of .filter_map(..).next()
let body = db.body(self.owner);
let mut prev = None;
for (id, expr) in body.exprs.iter() {
if let Expr::MethodCall { receiver, .. } = expr {
let function_id = match self.infer.method_resolution(id) {
Some((id, _)) => id,
None => continue,
};
if function_id == *filter_map_function_id {
prev = Some(id);
continue;
}
if function_id == *next_function_id {
if let Some(filter_map_id) = prev {
if *receiver == filter_map_id {
let (_, source_map) = db.body_with_source_map(self.owner);
if let Ok(next_source_ptr) = source_map.expr_syntax(id) {
self.sink.push(ReplaceFilterMapNextWithFindMap {
file: next_source_ptr.file_id,
next_expr: next_source_ptr.value,
});
}
}
}
}
}
prev = None;
}
}
fn validate_call(&mut self, db: &dyn HirDatabase, call_id: ExprId, expr: &Expr) {
// Check that the number of arguments matches the number of parameters.
// FIXME: Due to shortcomings in the current type system implementation, only emit this
// diagnostic if there are no type mismatches in the containing function.
if self.infer.expr_type_mismatches().next().is_some() {
return;
}
let is_method_call = matches!(expr, Expr::MethodCall { .. });
let (sig, args) = match expr {
Expr::Call { callee, args } => {
let callee = &self.infer.type_of_expr[*callee];
let sig = match callee.callable_sig(db) {
Some(sig) => sig,
None => return,
};
(sig, args.clone())
}
Expr::MethodCall { receiver, args, .. } => {
let mut args = args.clone();
args.insert(0, *receiver);
let receiver = &self.infer.type_of_expr[*receiver];
if receiver.strip_references().is_unknown() {
// if the receiver is of unknown type, it's very likely we
// don't know enough to correctly resolve the method call.
// This is kind of a band-aid for #6975.
return;
}
let (callee, subst) = match self.infer.method_resolution(call_id) {
Some(it) => it,
None => return,
};
let sig = db.callable_item_signature(callee.into()).substitute(&Interner, &subst);
(sig, args)
}
_ => return,
};
if sig.is_varargs {
return;
}
let params = sig.params();
let mut param_count = params.len();
let mut arg_count = args.len();
if arg_count != param_count {
let (_, source_map) = db.body_with_source_map(self.owner);
if let Ok(source_ptr) = source_map.expr_syntax(call_id) {
if is_method_call {
param_count -= 1;
arg_count -= 1;
}
self.sink.push(MismatchedArgCount {
file: source_ptr.file_id,
call_expr: source_ptr.value,
expected: param_count,
found: arg_count,
});
}
}
}
fn validate_match(
&mut self,
id: ExprId,
match_expr: ExprId,
arms: &[MatchArm],
db: &dyn HirDatabase,
infer: Arc<InferenceResult>,
) {
let (body, source_map): (Arc<Body>, Arc<BodySourceMap>) =
db.body_with_source_map(self.owner);
let match_expr_ty = if infer.type_of_expr[match_expr].is_unknown() {
return;
} else {
&infer.type_of_expr[match_expr]
};
let pattern_arena = RefCell::new(PatternArena::new());
let mut m_arms = Vec::new();
let mut has_lowering_errors = false;
for arm in arms {
if let Some(pat_ty) = infer.type_of_pat.get(arm.pat) {
// We only include patterns whose type matches the type
// of the match expression. If we had a InvalidMatchArmPattern
// diagnostic or similar we could raise that in an else
// block here.
//
// When comparing the types, we also have to consider that rustc
// will automatically de-reference the match expression type if
// necessary.
//
// FIXME we should use the type checker for this.
if (pat_ty == match_expr_ty
|| match_expr_ty
.as_reference()
.map(|(match_expr_ty, ..)| match_expr_ty == pat_ty)
.unwrap_or(false))
&& types_of_subpatterns_do_match(arm.pat, &body, &infer)
{
// If we had a NotUsefulMatchArm diagnostic, we could
// check the usefulness of each pattern as we added it
// to the matrix here.
let m_arm = match_check::MatchArm {
pat: self.lower_pattern(
arm.pat,
&mut pattern_arena.borrow_mut(),
db,
&body,
&mut has_lowering_errors,
),
has_guard: arm.guard.is_some(),
};
m_arms.push(m_arm);
if !has_lowering_errors {
continue;
}
}
}
// If we can't resolve the type of a pattern, or the pattern type doesn't
// fit the match expression, we skip this diagnostic. Skipping the entire
// diagnostic rather than just not including this match arm is preferred
// to avoid the chance of false positives.
#[cfg(test)]
match_check::tests::report_bail_out(db, self.owner, arm.pat, self.sink);
return;
}
let cx = MatchCheckCtx {
module: self.owner.module(db.upcast()),
match_expr,
infer: &infer,
db,
pattern_arena: &pattern_arena,
eprint_panic_context: &|| {
use syntax::AstNode;
if let Ok(scrutinee_sptr) = source_map.expr_syntax(match_expr) {
let root = scrutinee_sptr.file_syntax(db.upcast());
if let Some(match_ast) = scrutinee_sptr.value.to_node(&root).syntax().parent() {
eprintln!(
"Match checking is about to panic on this expression:\n{}",
match_ast.to_string(),
);
}
}
},
};
let report = compute_match_usefulness(&cx, &m_arms);
// FIXME Report unreacheble arms
// https://github.com/rust-lang/rust/blob/25c15cdbe/compiler/rustc_mir_build/src/thir/pattern/check_match.rs#L200-L201
let witnesses = report.non_exhaustiveness_witnesses;
// FIXME Report witnesses
// eprintln!("compute_match_usefulness(..) -> {:?}", &witnesses);
if !witnesses.is_empty() {
if let Ok(source_ptr) = source_map.expr_syntax(id) {
let root = source_ptr.file_syntax(db.upcast());
if let ast::Expr::MatchExpr(match_expr) = &source_ptr.value.to_node(&root) {
if let (Some(match_expr), Some(arms)) =
(match_expr.expr(), match_expr.match_arm_list())
{
self.sink.push(MissingMatchArms {
file: source_ptr.file_id,
match_expr: AstPtr::new(&match_expr),
arms: AstPtr::new(&arms),
})
}
}
}
}
}
fn lower_pattern(
&self,
pat: PatId,
pattern_arena: &mut PatternArena,
db: &dyn HirDatabase,
body: &Body,
have_errors: &mut bool,
) -> match_check::PatId {
let mut patcx = match_check::PatCtxt::new(db, &self.infer, body);
let pattern = patcx.lower_pattern(pat);
let pattern = pattern_arena.alloc(expand_pattern(pattern));
if !patcx.errors.is_empty() {
*have_errors = true;
}
pattern
}
fn validate_results_in_tail_expr(&mut self, body_id: ExprId, id: ExprId, db: &dyn HirDatabase) {
// the mismatch will be on the whole block currently
let mismatch = match self.infer.type_mismatch_for_expr(body_id) {
Some(m) => m,
None => return,
};
let core_result_path = path![core::result::Result];
let core_option_path = path![core::option::Option];
let resolver = self.owner.resolver(db.upcast());
let core_result_enum = match resolver.resolve_known_enum(db.upcast(), &core_result_path) {
Some(it) => it,
_ => return,
};
let core_option_enum = match resolver.resolve_known_enum(db.upcast(), &core_option_path) {
Some(it) => it,
_ => return,
};
let (params, required) = match mismatch.expected.kind(&Interner) {
TyKind::Adt(AdtId(hir_def::AdtId::EnumId(enum_id)), ref parameters)
if *enum_id == core_result_enum =>
{
(parameters, "Ok".to_string())
}
TyKind::Adt(AdtId(hir_def::AdtId::EnumId(enum_id)), ref parameters)
if *enum_id == core_option_enum =>
{
(parameters, "Some".to_string())
}
_ => return,
};
if params.len(&Interner) > 0
&& params.at(&Interner, 0).ty(&Interner) == Some(&mismatch.actual)
{
let (_, source_map) = db.body_with_source_map(self.owner);
if let Ok(source_ptr) = source_map.expr_syntax(id) {
self.sink.push(MissingOkOrSomeInTailExpr {
file: source_ptr.file_id,
expr: source_ptr.value,
required,
});
}
}
}
fn validate_missing_tail_expr(
&mut self,
body_id: ExprId,
possible_tail_id: ExprId,
db: &dyn HirDatabase,
) {
let mismatch = match self.infer.type_mismatch_for_expr(body_id) {
Some(m) => m,
None => return,
};
let possible_tail_ty = match self.infer.type_of_expr.get(possible_tail_id) {
Some(ty) => ty,
None => return,
};
if !mismatch.actual.is_unit() || mismatch.expected != *possible_tail_ty {
return;
}
let (_, source_map) = db.body_with_source_map(self.owner);
if let Ok(source_ptr) = source_map.expr_syntax(possible_tail_id) {
self.sink
.push(RemoveThisSemicolon { file: source_ptr.file_id, expr: source_ptr.value });
}
}
}
pub fn record_literal_missing_fields(
db: &dyn HirDatabase,
infer: &InferenceResult,
id: ExprId,
expr: &Expr,
) -> Option<(VariantId, Vec<LocalFieldId>, /*exhaustive*/ bool)> {
let (fields, exhaustive) = match expr {
Expr::RecordLit { path: _, fields, spread } => (fields, spread.is_none()),
_ => return None,
};
let variant_def = infer.variant_resolution_for_expr(id)?;
if let VariantId::UnionId(_) = variant_def {
return None;
}
let variant_data = variant_def.variant_data(db.upcast());
let specified_fields: FxHashSet<_> = fields.iter().map(|f| &f.name).collect();
let missed_fields: Vec<LocalFieldId> = variant_data
.fields()
.iter()
.filter_map(|(f, d)| if specified_fields.contains(&d.name) { None } else { Some(f) })
.collect();
if missed_fields.is_empty() {
return None;
}
Some((variant_def, missed_fields, exhaustive))
}
pub fn record_pattern_missing_fields(
db: &dyn HirDatabase,
infer: &InferenceResult,
id: PatId,
pat: &Pat,
) -> Option<(VariantId, Vec<LocalFieldId>, /*exhaustive*/ bool)> {
let (fields, exhaustive) = match pat {
Pat::Record { path: _, args, ellipsis } => (args, !ellipsis),
_ => return None,
};
let variant_def = infer.variant_resolution_for_pat(id)?;
if let VariantId::UnionId(_) = variant_def {
return None;
}
let variant_data = variant_def.variant_data(db.upcast());
let specified_fields: FxHashSet<_> = fields.iter().map(|f| &f.name).collect();
let missed_fields: Vec<LocalFieldId> = variant_data
.fields()
.iter()
.filter_map(|(f, d)| if specified_fields.contains(&d.name) { None } else { Some(f) })
.collect();
if missed_fields.is_empty() {
return None;
}
Some((variant_def, missed_fields, exhaustive))
}
fn types_of_subpatterns_do_match(pat: PatId, body: &Body, infer: &InferenceResult) -> bool {
fn walk(pat: PatId, body: &Body, infer: &InferenceResult, has_type_mismatches: &mut bool) {
match infer.type_mismatch_for_pat(pat) {
Some(_) => *has_type_mismatches = true,
None => {
body[pat].walk_child_pats(|subpat| walk(subpat, body, infer, has_type_mismatches))
}
}
}
let mut has_type_mismatches = false;
walk(pat, body, infer, &mut has_type_mismatches);
!has_type_mismatches
}
#[cfg(test)]
mod tests {
use crate::diagnostics::tests::check_diagnostics;
#[test]
fn simple_free_fn_zero() {
check_diagnostics(
r#"
fn zero() {}
fn f() { zero(1); }
//^^^^^^^ Expected 0 arguments, found 1
"#,
);
check_diagnostics(
r#"
fn zero() {}
fn f() { zero(); }
"#,
);
}
#[test]
fn simple_free_fn_one() {
check_diagnostics(
r#"
fn one(arg: u8) {}
fn f() { one(); }
//^^^^^ Expected 1 argument, found 0
"#,
);
check_diagnostics(
r#"
fn one(arg: u8) {}
fn f() { one(1); }
"#,
);
}
#[test]
fn method_as_fn() {
check_diagnostics(
r#"
struct S;
impl S { fn method(&self) {} }
fn f() {
S::method();
} //^^^^^^^^^^^ Expected 1 argument, found 0
"#,
);
check_diagnostics(
r#"
struct S;
impl S { fn method(&self) {} }
fn f() {
S::method(&S);
S.method();
}
"#,
);
}
#[test]
fn method_with_arg() {
check_diagnostics(
r#"
struct S;
impl S { fn method(&self, arg: u8) {} }
fn f() {
S.method();
} //^^^^^^^^^^ Expected 1 argument, found 0
"#,
);
check_diagnostics(
r#"
struct S;
impl S { fn method(&self, arg: u8) {} }
fn f() {
S::method(&S, 0);
S.method(1);
}
"#,
);
}
#[test]
fn method_unknown_receiver() {
// note: this is incorrect code, so there might be errors on this in the
// future, but we shouldn't emit an argument count diagnostic here
check_diagnostics(
r#"
trait Foo { fn method(&self, arg: usize) {} }
fn f() {
let x;
x.method();
}
"#,
);
}
#[test]
fn tuple_struct() {
check_diagnostics(
r#"
struct Tup(u8, u16);
fn f() {
Tup(0);
} //^^^^^^ Expected 2 arguments, found 1
"#,
)
}
#[test]
fn enum_variant() {
check_diagnostics(
r#"
enum En { Variant(u8, u16), }
fn f() {
En::Variant(0);
} //^^^^^^^^^^^^^^ Expected 2 arguments, found 1
"#,
)
}
#[test]
fn enum_variant_type_macro() {
check_diagnostics(
r#"
macro_rules! Type {
() => { u32 };
}
enum Foo {
Bar(Type![])
}
impl Foo {
fn new() {
Foo::Bar(0);
Foo::Bar(0, 1);
//^^^^^^^^^^^^^^ Expected 1 argument, found 2
Foo::Bar();
//^^^^^^^^^^ Expected 1 argument, found 0
}
}
"#,
);
}
#[test]
fn varargs() {
check_diagnostics(
r#"
extern "C" {
fn fixed(fixed: u8);
fn varargs(fixed: u8, ...);
fn varargs2(...);
}
fn f() {
unsafe {
fixed(0);
fixed(0, 1);
//^^^^^^^^^^^ Expected 1 argument, found 2
varargs(0);
varargs(0, 1);
varargs2();
varargs2(0);
varargs2(0, 1);
}
}
"#,
)
}
#[test]
fn arg_count_lambda() {
check_diagnostics(
r#"
fn main() {
let f = |()| ();
f();
//^^^ Expected 1 argument, found 0
f(());
f((), ());
//^^^^^^^^^ Expected 1 argument, found 2
}
"#,
)
}
#[test]
fn cfgd_out_call_arguments() {
check_diagnostics(
r#"
struct C(#[cfg(FALSE)] ());
impl C {
fn new() -> Self {
Self(
#[cfg(FALSE)]
(),
)
}
fn method(&self) {}
}
fn main() {
C::new().method(#[cfg(FALSE)] 0);
}
"#,
);
}
#[test]
fn cfgd_out_fn_params() {
check_diagnostics(
r#"
fn foo(#[cfg(NEVER)] x: ()) {}
struct S;
impl S {
fn method(#[cfg(NEVER)] self) {}
fn method2(#[cfg(NEVER)] self, arg: u8) {}
fn method3(self, #[cfg(NEVER)] arg: u8) {}
}
extern "C" {
fn fixed(fixed: u8, #[cfg(NEVER)] ...);
fn varargs(#[cfg(not(NEVER))] ...);
}
fn main() {
foo();
S::method();
S::method2(0);
S::method3(S);
S.method3();
unsafe {
fixed(0);
varargs(1, 2, 3);
}
}
"#,
)
}
}