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Diffstat (limited to '')
| -rw-r--r-- | src/tools/clippy/clippy_lints/src/utils/internal_lints/collapsible_calls.rs | 245 |
1 files changed, 245 insertions, 0 deletions
diff --git a/src/tools/clippy/clippy_lints/src/utils/internal_lints/collapsible_calls.rs b/src/tools/clippy/clippy_lints/src/utils/internal_lints/collapsible_calls.rs new file mode 100644 index 000000000..d7666b77f --- /dev/null +++ b/src/tools/clippy/clippy_lints/src/utils/internal_lints/collapsible_calls.rs @@ -0,0 +1,245 @@ +use clippy_utils::diagnostics::span_lint_and_sugg; +use clippy_utils::source::snippet; +use clippy_utils::{is_expr_path_def_path, is_lint_allowed, peel_blocks_with_stmt, SpanlessEq}; +use if_chain::if_chain; +use rustc_errors::Applicability; +use rustc_hir as hir; +use rustc_hir::{Closure, Expr, ExprKind}; +use rustc_lint::{LateContext, LateLintPass}; +use rustc_session::{declare_lint_pass, declare_tool_lint}; + +use std::borrow::{Borrow, Cow}; + +declare_clippy_lint! { + /// ### What it does + /// Lints `span_lint_and_then` function calls, where the + /// closure argument has only one statement and that statement is a method + /// call to `span_suggestion`, `span_help`, `span_note` (using the same + /// span), `help` or `note`. + /// + /// These usages of `span_lint_and_then` should be replaced with one of the + /// wrapper functions `span_lint_and_sugg`, span_lint_and_help`, or + /// `span_lint_and_note`. + /// + /// ### Why is this bad? + /// Using the wrapper `span_lint_and_*` functions, is more + /// convenient, readable and less error prone. + /// + /// ### Example + /// ```rust,ignore + /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| { + /// diag.span_suggestion( + /// expr.span, + /// help_msg, + /// sugg.to_string(), + /// Applicability::MachineApplicable, + /// ); + /// }); + /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| { + /// diag.span_help(expr.span, help_msg); + /// }); + /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| { + /// diag.help(help_msg); + /// }); + /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| { + /// diag.span_note(expr.span, note_msg); + /// }); + /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| { + /// diag.note(note_msg); + /// }); + /// ``` + /// + /// Use instead: + /// ```rust,ignore + /// span_lint_and_sugg( + /// cx, + /// TEST_LINT, + /// expr.span, + /// lint_msg, + /// help_msg, + /// sugg.to_string(), + /// Applicability::MachineApplicable, + /// ); + /// span_lint_and_help(cx, TEST_LINT, expr.span, lint_msg, Some(expr.span), help_msg); + /// span_lint_and_help(cx, TEST_LINT, expr.span, lint_msg, None, help_msg); + /// span_lint_and_note(cx, TEST_LINT, expr.span, lint_msg, Some(expr.span), note_msg); + /// span_lint_and_note(cx, TEST_LINT, expr.span, lint_msg, None, note_msg); + /// ``` + pub COLLAPSIBLE_SPAN_LINT_CALLS, + internal, + "found collapsible `span_lint_and_then` calls" +} + +declare_lint_pass!(CollapsibleCalls => [COLLAPSIBLE_SPAN_LINT_CALLS]); + +impl<'tcx> LateLintPass<'tcx> for CollapsibleCalls { + fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) { + if is_lint_allowed(cx, COLLAPSIBLE_SPAN_LINT_CALLS, expr.hir_id) { + return; + } + + if_chain! { + if let ExprKind::Call(func, and_then_args) = expr.kind; + if is_expr_path_def_path(cx, func, &["clippy_utils", "diagnostics", "span_lint_and_then"]); + if and_then_args.len() == 5; + if let ExprKind::Closure(&Closure { body, .. }) = &and_then_args[4].kind; + let body = cx.tcx.hir().body(body); + let only_expr = peel_blocks_with_stmt(body.value); + if let ExprKind::MethodCall(ps, recv, span_call_args, _) = &only_expr.kind; + if let ExprKind::Path(..) = recv.kind; + then { + let and_then_snippets = get_and_then_snippets(cx, and_then_args); + let mut sle = SpanlessEq::new(cx).deny_side_effects(); + match ps.ident.as_str() { + "span_suggestion" if sle.eq_expr(&and_then_args[2], &span_call_args[0]) => { + suggest_suggestion( + cx, + expr, + &and_then_snippets, + &span_suggestion_snippets(cx, span_call_args), + ); + }, + "span_help" if sle.eq_expr(&and_then_args[2], &span_call_args[0]) => { + let help_snippet = snippet(cx, span_call_args[1].span, r#""...""#); + suggest_help(cx, expr, &and_then_snippets, help_snippet.borrow(), true); + }, + "span_note" if sle.eq_expr(&and_then_args[2], &span_call_args[0]) => { + let note_snippet = snippet(cx, span_call_args[1].span, r#""...""#); + suggest_note(cx, expr, &and_then_snippets, note_snippet.borrow(), true); + }, + "help" => { + let help_snippet = snippet(cx, span_call_args[0].span, r#""...""#); + suggest_help(cx, expr, &and_then_snippets, help_snippet.borrow(), false); + }, + "note" => { + let note_snippet = snippet(cx, span_call_args[0].span, r#""...""#); + suggest_note(cx, expr, &and_then_snippets, note_snippet.borrow(), false); + }, + _ => (), + } + } + } + } +} + +struct AndThenSnippets<'a> { + cx: Cow<'a, str>, + lint: Cow<'a, str>, + span: Cow<'a, str>, + msg: Cow<'a, str>, +} + +fn get_and_then_snippets<'a, 'hir>(cx: &LateContext<'_>, and_then_snippets: &'hir [Expr<'hir>]) -> AndThenSnippets<'a> { + let cx_snippet = snippet(cx, and_then_snippets[0].span, "cx"); + let lint_snippet = snippet(cx, and_then_snippets[1].span, ".."); + let span_snippet = snippet(cx, and_then_snippets[2].span, "span"); + let msg_snippet = snippet(cx, and_then_snippets[3].span, r#""...""#); + + AndThenSnippets { + cx: cx_snippet, + lint: lint_snippet, + span: span_snippet, + msg: msg_snippet, + } +} + +struct SpanSuggestionSnippets<'a> { + help: Cow<'a, str>, + sugg: Cow<'a, str>, + applicability: Cow<'a, str>, +} + +fn span_suggestion_snippets<'a, 'hir>( + cx: &LateContext<'_>, + span_call_args: &'hir [Expr<'hir>], +) -> SpanSuggestionSnippets<'a> { + let help_snippet = snippet(cx, span_call_args[1].span, r#""...""#); + let sugg_snippet = snippet(cx, span_call_args[2].span, ".."); + let applicability_snippet = snippet(cx, span_call_args[3].span, "Applicability::MachineApplicable"); + + SpanSuggestionSnippets { + help: help_snippet, + sugg: sugg_snippet, + applicability: applicability_snippet, + } +} + +fn suggest_suggestion( + cx: &LateContext<'_>, + expr: &Expr<'_>, + and_then_snippets: &AndThenSnippets<'_>, + span_suggestion_snippets: &SpanSuggestionSnippets<'_>, +) { + span_lint_and_sugg( + cx, + COLLAPSIBLE_SPAN_LINT_CALLS, + expr.span, + "this call is collapsible", + "collapse into", + format!( + "span_lint_and_sugg({}, {}, {}, {}, {}, {}, {})", + and_then_snippets.cx, + and_then_snippets.lint, + and_then_snippets.span, + and_then_snippets.msg, + span_suggestion_snippets.help, + span_suggestion_snippets.sugg, + span_suggestion_snippets.applicability + ), + Applicability::MachineApplicable, + ); +} + +fn suggest_help( + cx: &LateContext<'_>, + expr: &Expr<'_>, + and_then_snippets: &AndThenSnippets<'_>, + help: &str, + with_span: bool, +) { + let option_span = if with_span { + format!("Some({})", and_then_snippets.span) + } else { + "None".to_string() + }; + + span_lint_and_sugg( + cx, + COLLAPSIBLE_SPAN_LINT_CALLS, + expr.span, + "this call is collapsible", + "collapse into", + format!( + "span_lint_and_help({}, {}, {}, {}, {}, {help})", + and_then_snippets.cx, and_then_snippets.lint, and_then_snippets.span, and_then_snippets.msg, &option_span, + ), + Applicability::MachineApplicable, + ); +} + +fn suggest_note( + cx: &LateContext<'_>, + expr: &Expr<'_>, + and_then_snippets: &AndThenSnippets<'_>, + note: &str, + with_span: bool, +) { + let note_span = if with_span { + format!("Some({})", and_then_snippets.span) + } else { + "None".to_string() + }; + + span_lint_and_sugg( + cx, + COLLAPSIBLE_SPAN_LINT_CALLS, + expr.span, + "this call is collapsible", + "collapse into", + format!( + "span_lint_and_note({}, {}, {}, {}, {note_span}, {note})", + and_then_snippets.cx, and_then_snippets.lint, and_then_snippets.span, and_then_snippets.msg, + ), + Applicability::MachineApplicable, + ); +} |