simplify the suggestion notes
This commit is contained in:
Ding Xiang Fei
parent
89682a5313
commit
b4b2b356d9
7 changed files with 205 additions and 385 deletions
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@ -7,7 +7,7 @@ use rustc_errors::{
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Applicability, Diag, EmissionGuarantee, SubdiagMessageOp, Subdiagnostic, SuggestionStyle,
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};
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use rustc_hir::{self as hir, HirIdSet};
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use rustc_macros::{LintDiagnostic, Subdiagnostic};
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use rustc_macros::LintDiagnostic;
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use rustc_middle::ty::TyCtxt;
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use rustc_session::lint::{FutureIncompatibilityReason, Level};
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use rustc_session::{declare_lint, impl_lint_pass};
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@ -124,103 +124,109 @@ impl IfLetRescope {
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let source_map = tcx.sess.source_map();
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let expr_end = expr.span.shrink_to_hi();
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let mut add_bracket_to_match_head = match_head_needs_bracket(tcx, expr);
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let mut significant_droppers = vec![];
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let mut lifetime_ends = vec![];
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let mut closing_brackets = 0;
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let mut alt_heads = vec![];
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let mut match_heads = vec![];
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let mut consequent_heads = vec![];
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let mut first_if_to_rewrite = None;
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let mut first_if_to_lint = None;
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let mut first_if_to_rewrite = false;
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let mut empty_alt = false;
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while let hir::ExprKind::If(cond, conseq, alt) = expr.kind {
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self.skip.insert(expr.hir_id);
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let hir::ExprKind::Let(&hir::LetExpr {
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// We are interested in `let` fragment of the condition.
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// Otherwise, we probe into the `else` fragment.
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if let hir::ExprKind::Let(&hir::LetExpr {
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span,
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pat,
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init,
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ty: ty_ascription,
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recovered: Recovered::No,
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}) = cond.kind
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else {
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if let Some(alt) = alt {
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add_bracket_to_match_head = matches!(alt.kind, hir::ExprKind::If(..));
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expr = alt;
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continue;
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} else {
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// finalize and emit span
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break;
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}
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};
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let if_let_pat = expr.span.shrink_to_lo().between(init.span);
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// the consequent fragment is always a block
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let before_conseq = conseq.span.shrink_to_lo();
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let lifetime_end = source_map.end_point(conseq.span);
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if let ControlFlow::Break(significant_dropper) =
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(FindSignificantDropper { cx }).visit_expr(init)
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{
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tcx.emit_node_span_lint(
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IF_LET_RESCOPE,
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expr.hir_id,
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span,
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IfLetRescopeLint { significant_dropper, lifetime_end },
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);
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if ty_ascription.is_some()
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|| !expr.span.can_be_used_for_suggestions()
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|| !pat.span.can_be_used_for_suggestions()
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let if_let_pat = expr.span.shrink_to_lo().between(init.span);
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// The consequent fragment is always a block.
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let before_conseq = conseq.span.shrink_to_lo();
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let lifetime_end = source_map.end_point(conseq.span);
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if let ControlFlow::Break(significant_dropper) =
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(FindSignificantDropper { cx }).visit_expr(init)
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{
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// Our `match` rewrites does not support type ascription,
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// so we just bail.
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// Alternatively when the span comes from proc macro expansion,
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// we will also bail.
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// FIXME(#101728): change this when type ascription syntax is stabilized again
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} else if let Ok(pat) = source_map.span_to_snippet(pat.span) {
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let emit_suggestion = || {
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first_if_to_rewrite =
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first_if_to_rewrite.or_else(|| Some((expr.span, expr.hir_id)));
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if add_bracket_to_match_head {
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closing_brackets += 2;
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match_heads.push(SingleArmMatchBegin::WithOpenBracket(if_let_pat));
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first_if_to_lint = first_if_to_lint.or_else(|| Some((span, expr.hir_id)));
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significant_droppers.push(significant_dropper);
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lifetime_ends.push(lifetime_end);
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if ty_ascription.is_some()
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|| !expr.span.can_be_used_for_suggestions()
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|| !pat.span.can_be_used_for_suggestions()
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{
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// Our `match` rewrites does not support type ascription,
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// so we just bail.
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// Alternatively when the span comes from proc macro expansion,
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// we will also bail.
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// FIXME(#101728): change this when type ascription syntax is stabilized again
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} else if let Ok(pat) = source_map.span_to_snippet(pat.span) {
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let emit_suggestion = |alt_span| {
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first_if_to_rewrite = true;
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if add_bracket_to_match_head {
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closing_brackets += 2;
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match_heads.push(SingleArmMatchBegin::WithOpenBracket(if_let_pat));
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} else {
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// Sometimes, wrapping `match` into a block is undesirable,
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// because the scrutinee temporary lifetime is shortened and
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// the proposed fix will not work.
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closing_brackets += 1;
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match_heads
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.push(SingleArmMatchBegin::WithoutOpenBracket(if_let_pat));
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}
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consequent_heads.push(ConsequentRewrite { span: before_conseq, pat });
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if let Some(alt_span) = alt_span {
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alt_heads.push(AltHead(alt_span));
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}
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};
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if let Some(alt) = alt {
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let alt_head = conseq.span.between(alt.span);
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if alt_head.can_be_used_for_suggestions() {
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// We lint only when the `else` span is user code, too.
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emit_suggestion(Some(alt_head));
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}
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} else {
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// It has to be a block
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closing_brackets += 1;
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match_heads.push(SingleArmMatchBegin::WithoutOpenBracket(if_let_pat));
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// This is the end of the `if .. else ..` cascade.
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// We can stop here.
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emit_suggestion(None);
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empty_alt = true;
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break;
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}
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consequent_heads.push(ConsequentRewrite { span: before_conseq, pat });
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};
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if let Some(alt) = alt {
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let alt_head = conseq.span.between(alt.span);
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if alt_head.can_be_used_for_suggestions() {
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// lint
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emit_suggestion();
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alt_heads.push(AltHead(alt_head));
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}
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} else {
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emit_suggestion();
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empty_alt = true;
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break;
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}
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}
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}
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// At this point, any `if let` fragment in the cascade is definitely preceeded by `else`,
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// so a opening bracket is mandatory before each `match`.
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add_bracket_to_match_head = true;
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if let Some(alt) = alt {
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add_bracket_to_match_head = matches!(alt.kind, hir::ExprKind::If(..));
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expr = alt;
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} else {
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break;
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}
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}
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if let Some((span, hir_id)) = first_if_to_rewrite {
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if let Some((span, hir_id)) = first_if_to_lint {
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tcx.emit_node_span_lint(
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IF_LET_RESCOPE,
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hir_id,
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span,
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IfLetRescopeRewrite {
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match_heads,
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consequent_heads,
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closing_brackets: ClosingBrackets {
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span: expr_end,
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count: closing_brackets,
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empty_alt,
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},
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alt_heads,
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IfLetRescopeLint {
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significant_droppers,
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lifetime_ends,
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rewrite: first_if_to_rewrite.then_some(IfLetRescopeRewrite {
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match_heads,
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consequent_heads,
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closing_brackets: ClosingBrackets {
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span: expr_end,
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count: closing_brackets,
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empty_alt,
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},
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alt_heads,
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}),
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},
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);
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}
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@ -254,32 +260,68 @@ impl<'tcx> LateLintPass<'tcx> for IfLetRescope {
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#[diag(lint_if_let_rescope)]
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struct IfLetRescopeLint {
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#[label]
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significant_dropper: Span,
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significant_droppers: Vec<Span>,
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#[help]
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lifetime_end: Span,
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lifetime_ends: Vec<Span>,
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#[subdiagnostic]
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rewrite: Option<IfLetRescopeRewrite>,
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}
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#[derive(LintDiagnostic)]
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#[diag(lint_if_let_rescope_suggestion)]
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// #[derive(Subdiagnostic)]
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struct IfLetRescopeRewrite {
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#[subdiagnostic]
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match_heads: Vec<SingleArmMatchBegin>,
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#[subdiagnostic]
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consequent_heads: Vec<ConsequentRewrite>,
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#[subdiagnostic]
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closing_brackets: ClosingBrackets,
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#[subdiagnostic]
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alt_heads: Vec<AltHead>,
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}
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#[derive(Subdiagnostic)]
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#[multipart_suggestion(lint_suggestion, applicability = "machine-applicable")]
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struct AltHead(#[suggestion_part(code = " _ => ")] Span);
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impl Subdiagnostic for IfLetRescopeRewrite {
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fn add_to_diag_with<G: EmissionGuarantee, F: SubdiagMessageOp<G>>(
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self,
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diag: &mut Diag<'_, G>,
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f: &F,
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) {
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let mut suggestions = vec![];
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for match_head in self.match_heads {
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match match_head {
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SingleArmMatchBegin::WithOpenBracket(span) => {
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suggestions.push((span, "{ match ".into()))
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}
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SingleArmMatchBegin::WithoutOpenBracket(span) => {
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suggestions.push((span, "match ".into()))
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}
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}
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}
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for ConsequentRewrite { span, pat } in self.consequent_heads {
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suggestions.push((span, format!("{{ {pat} => ")));
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}
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for AltHead(span) in self.alt_heads {
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suggestions.push((span, " _ => ".into()));
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}
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let closing_brackets = self.closing_brackets;
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suggestions.push((
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closing_brackets.span,
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closing_brackets
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.empty_alt
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.then_some(" _ => {}".chars())
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.into_iter()
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.flatten()
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.chain(repeat('}').take(closing_brackets.count))
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.collect(),
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));
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let msg = f(diag, crate::fluent_generated::lint_suggestion.into());
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diag.multipart_suggestion_with_style(
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msg,
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suggestions,
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Applicability::MachineApplicable,
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SuggestionStyle::ShowCode,
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);
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}
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}
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struct AltHead(Span);
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#[derive(Subdiagnostic)]
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#[multipart_suggestion(lint_suggestion, applicability = "machine-applicable")]
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struct ConsequentRewrite {
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#[suggestion_part(code = "{{ {pat} => ")]
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span: Span,
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pat: String,
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}
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@ -289,36 +331,9 @@ struct ClosingBrackets {
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count: usize,
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empty_alt: bool,
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}
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impl Subdiagnostic for ClosingBrackets {
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fn add_to_diag_with<G: EmissionGuarantee, F: SubdiagMessageOp<G>>(
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self,
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diag: &mut Diag<'_, G>,
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f: &F,
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) {
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let code: String = self
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.empty_alt
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.then_some(" _ => {}".chars())
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.into_iter()
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.flatten()
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.chain(repeat('}').take(self.count))
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.collect();
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let msg = f(diag, crate::fluent_generated::lint_suggestion.into());
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diag.multipart_suggestion_with_style(
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msg,
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vec![(self.span, code)],
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Applicability::MachineApplicable,
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SuggestionStyle::ShowCode,
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);
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}
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}
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#[derive(Subdiagnostic)]
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enum SingleArmMatchBegin {
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#[multipart_suggestion(lint_suggestion, applicability = "machine-applicable")]
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WithOpenBracket(#[suggestion_part(code = "{{ match ")] Span),
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#[multipart_suggestion(lint_suggestion, applicability = "machine-applicable")]
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WithoutOpenBracket(#[suggestion_part(code = "match ")] Span),
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WithOpenBracket(Span),
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WithoutOpenBracket(Span),
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}
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struct FindSignificantDropper<'tcx, 'a> {
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