bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Handle let-else initializer edge case errors

Browse source
This commit is contained in:
Cameron Steffen 2021-07-30 17:12:11 -05:00
parent 2f4e86b9ef
commit 29bc94ff0d
3 changed files with 101 additions and 15 deletions
Download patch file Download diff file Expand all files Collapse all files

43
compiler/rustc_lint/src/unused.rs
View file

@ -1,7 +1,7 @@
use crate::Lint;
use crate::{EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext};
use rustc_ast as ast;
use rustc_ast::util::parser;
use rustc_ast::util::{classify, parser};
use rustc_ast::{ExprKind, StmtKind};
use rustc_ast_pretty::pprust;
use rustc_errors::{pluralize, Applicability};
@ -382,6 +382,7 @@ enum UnusedDelimsCtx {
FunctionArg,
MethodArg,
AssignedValue,
AssignedValueLetElse,
IfCond,
WhileCond,
ForIterExpr,
@ -398,7 +399,9 @@ impl From<UnusedDelimsCtx> for &'static str {
match ctx {
UnusedDelimsCtx::FunctionArg => "function argument",
UnusedDelimsCtx::MethodArg => "method argument",
UnusedDelimsCtx::AssignedValue => "assigned value",
UnusedDelimsCtx::AssignedValue | UnusedDelimsCtx::AssignedValueLetElse => {
"assigned value"
}
UnusedDelimsCtx::IfCond => "`if` condition",
UnusedDelimsCtx::WhileCond => "`while` condition",
UnusedDelimsCtx::ForIterExpr => "`for` iterator expression",
@ -441,14 +444,26 @@ trait UnusedDelimLint {
right_pos: Option<BytePos>,
);
fn is_expr_delims_necessary(inner: &ast::Expr, followed_by_block: bool) -> bool {
fn is_expr_delims_necessary(
inner: &ast::Expr,
followed_by_block: bool,
followed_by_else: bool,
) -> bool {
if followed_by_else {
match inner.kind {
ast::ExprKind::Binary(op, ..) if op.node.lazy() => return true,
_ if classify::expr_trailing_brace(inner).is_some() => return true,
_ => {}
}
}
// Prevent false-positives in cases like `fn x() -> u8 { ({ 0 } + 1) }`
let lhs_needs_parens = {
let mut innermost = inner;
loop {
if let ExprKind::Binary(_, lhs, _rhs) = &innermost.kind {
innermost = lhs;
if !rustc_ast::util::classify::expr_requires_semi_to_be_stmt(innermost) {
if !classify::expr_requires_semi_to_be_stmt(innermost) {
break true;
}
} else {
@ -618,15 +633,12 @@ trait UnusedDelimLint {
fn check_stmt(&mut self, cx: &EarlyContext<'_>, s: &ast::Stmt) {
match s.kind {
StmtKind::Local(ref local) if Self::LINT_EXPR_IN_PATTERN_MATCHING_CTX => {
if let Some(value) = local.kind.init() {
self.check_unused_delims_expr(
cx,
&value,
UnusedDelimsCtx::AssignedValue,
false,
None,
None,
);
if let Some((init, els)) = local.kind.init_else_opt() {
let ctx = match els {
None => UnusedDelimsCtx::AssignedValue,
Some(_) => UnusedDelimsCtx::AssignedValueLetElse,
};
self.check_unused_delims_expr(cx, init, ctx, false, None, None);
}
}
StmtKind::Expr(ref expr) => {
@ -702,7 +714,8 @@ impl UnusedDelimLint for UnusedParens {
) {
match value.kind {
ast::ExprKind::Paren(ref inner) => {
if !Self::is_expr_delims_necessary(inner, followed_by_block)
let followed_by_else = ctx == UnusedDelimsCtx::AssignedValueLetElse;
if !Self::is_expr_delims_necessary(inner, followed_by_block, followed_by_else)
&& value.attrs.is_empty()
&& !value.span.from_expansion()
&& (ctx != UnusedDelimsCtx::LetScrutineeExpr
@ -941,7 +954,7 @@ impl UnusedDelimLint for UnusedBraces {
// FIXME(const_generics): handle paths when #67075 is fixed.
if let [stmt] = inner.stmts.as_slice() {
if let ast::StmtKind::Expr(ref expr) = stmt.kind {
if !Self::is_expr_delims_necessary(expr, followed_by_block)
if !Self::is_expr_delims_necessary(expr, followed_by_block, false)
&& (ctx != UnusedDelimsCtx::AnonConst
|| matches!(expr.kind, ast::ExprKind::Lit(_)))
&& !cx.sess().source_map().is_multiline(value.span)