From 2ae8b300a7f55f5cf132b640ad6a5727ba282d1e Mon Sep 17 00:00:00 2001 From: Jason Newcomb Date: Wed, 13 Apr 2022 00:36:13 -0400 Subject: [PATCH] Don't lint `unit_arg` when expanded from a proc-macro --- clippy_lints/src/matches/mod.rs | 6 +- clippy_lints/src/unit_types/unit_arg.rs | 3 +- clippy_utils/src/check_proc_macro.rs | 167 ++++++++++++++++++++++++ clippy_utils/src/lib.rs | 2 + clippy_utils/src/source.rs | 18 --- tests/ui/unit_arg.rs | 12 +- tests/ui/unit_arg.stderr | 20 +-- 7 files changed, 195 insertions(+), 33 deletions(-) create mode 100644 clippy_utils/src/check_proc_macro.rs diff --git a/clippy_lints/src/matches/mod.rs b/clippy_lints/src/matches/mod.rs index b638f271602..a74166c32d1 100644 --- a/clippy_lints/src/matches/mod.rs +++ b/clippy_lints/src/matches/mod.rs @@ -21,8 +21,8 @@ mod single_match; mod try_err; mod wild_in_or_pats; -use clippy_utils::source::{snippet_opt, span_starts_with, walk_span_to_context}; -use clippy_utils::{higher, in_constant, meets_msrv, msrvs}; +use clippy_utils::source::{snippet_opt, walk_span_to_context}; +use clippy_utils::{higher, in_constant, is_span_match, meets_msrv, msrvs}; use rustc_hir::{Arm, Expr, ExprKind, Local, MatchSource, Pat}; use rustc_lexer::{tokenize, TokenKind}; use rustc_lint::{LateContext, LateLintPass, LintContext}; @@ -949,7 +949,7 @@ impl<'tcx> LateLintPass<'tcx> for Matches { let from_expansion = expr.span.from_expansion(); if let ExprKind::Match(ex, arms, source) = expr.kind { - if source == MatchSource::Normal && !span_starts_with(cx, expr.span, "match") { + if source == MatchSource::Normal && !is_span_match(cx, expr.span) { return; } if matches!(source, MatchSource::Normal | MatchSource::ForLoopDesugar) { diff --git a/clippy_lints/src/unit_types/unit_arg.rs b/clippy_lints/src/unit_types/unit_arg.rs index 97d92f10e1c..cd38720f722 100644 --- a/clippy_lints/src/unit_types/unit_arg.rs +++ b/clippy_lints/src/unit_types/unit_arg.rs @@ -1,4 +1,5 @@ use clippy_utils::diagnostics::span_lint_and_then; +use clippy_utils::is_expr_from_proc_macro; use clippy_utils::source::{indent_of, reindent_multiline, snippet_opt}; use if_chain::if_chain; use rustc_errors::Applicability; @@ -44,7 +45,7 @@ pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>) { } }) .collect::>(); - if !args_to_recover.is_empty() { + if !args_to_recover.is_empty() && !is_expr_from_proc_macro(cx, expr) { lint_unit_args(cx, expr, &args_to_recover); } }, diff --git a/clippy_utils/src/check_proc_macro.rs b/clippy_utils/src/check_proc_macro.rs new file mode 100644 index 00000000000..387bf720008 --- /dev/null +++ b/clippy_utils/src/check_proc_macro.rs @@ -0,0 +1,167 @@ +//! This module handles checking if the span given is from a proc-macro or not. +//! +//! Proc-macros are capable of setting the span of every token they output to a few possible spans. +//! This includes spans we can detect easily as coming from a proc-macro (e.g. the call site +//! or the def site), and spans we can't easily detect as such (e.g. the span of any token +//! passed into the proc macro). This capability means proc-macros are capable of generating code +//! with a span that looks like it was written by the user, but which should not be linted by clippy +//! as it was generated by an external macro. +//! +//! That brings us to this module. The current approach is to determine a small bit of text which +//! must exist at both the start and the end of an item (e.g. an expression or a path) assuming the +//! code was written, and check if the span contains that text. Note this will only work correctly +//! if the span is not from a `macro_rules` based macro. + +use rustc_ast::ast::{IntTy, LitIntType, LitKind, StrStyle, UintTy}; +use rustc_hir::{ + Block, BlockCheckMode, Closure, Destination, Expr, ExprKind, LoopSource, MatchSource, QPath, UnOp, UnsafeSource, + YieldSource, +}; +use rustc_lint::{LateContext, LintContext}; +use rustc_middle::ty::TyCtxt; +use rustc_session::Session; +use rustc_span::{Span, Symbol}; + +#[derive(Clone, Copy)] +enum Pat { + Str(&'static str), + Sym(Symbol), + Num, +} + +/// Checks if the start and the end of the span's text matches the patterns. This will return false +/// if the span crosses multiple files or if source is not available. +fn span_matches_pat(sess: &Session, span: Span, start_pat: Pat, end_pat: Pat) -> bool { + let pos = sess.source_map().lookup_byte_offset(span.lo()); + let Some(ref src) = pos.sf.src else { + return false; + }; + let end = span.hi() - pos.sf.start_pos; + src.get(pos.pos.0 as usize..end.0 as usize).map_or(false, |s| { + // Spans can be wrapped in a mixture or parenthesis, whitespace, and trailing commas. + let start_str = s.trim_start_matches(|c: char| c.is_whitespace() || c == '('); + let end_str = s.trim_end_matches(|c: char| c.is_whitespace() || c == ')' || c == ','); + (match start_pat { + Pat::Str(text) => start_str.starts_with(text), + Pat::Sym(sym) => start_str.starts_with(sym.as_str()), + Pat::Num => start_str.as_bytes().first().map_or(false, u8::is_ascii_digit), + } && match end_pat { + Pat::Str(text) => end_str.ends_with(text), + Pat::Sym(sym) => end_str.ends_with(sym.as_str()), + Pat::Num => end_str.as_bytes().last().map_or(false, u8::is_ascii_hexdigit), + }) + }) +} + +/// Get the search patterns to use for the given literal +fn lit_search_pat(lit: &LitKind) -> (Pat, Pat) { + match lit { + LitKind::Str(_, StrStyle::Cooked) => (Pat::Str("\""), Pat::Str("\"")), + LitKind::Str(_, StrStyle::Raw(0)) => (Pat::Str("r"), Pat::Str("\"")), + LitKind::Str(_, StrStyle::Raw(_)) => (Pat::Str("r#"), Pat::Str("#")), + LitKind::ByteStr(_) => (Pat::Str("b\""), Pat::Str("\"")), + LitKind::Byte(_) => (Pat::Str("b'"), Pat::Str("'")), + LitKind::Char(_) => (Pat::Str("'"), Pat::Str("'")), + LitKind::Int(_, LitIntType::Signed(IntTy::Isize)) => (Pat::Num, Pat::Str("isize")), + LitKind::Int(_, LitIntType::Unsigned(UintTy::Usize)) => (Pat::Num, Pat::Str("usize")), + LitKind::Int(..) => (Pat::Num, Pat::Num), + LitKind::Float(..) => (Pat::Num, Pat::Str("")), + LitKind::Bool(true) => (Pat::Str("true"), Pat::Str("true")), + LitKind::Bool(false) => (Pat::Str("false"), Pat::Str("false")), + _ => (Pat::Str(""), Pat::Str("")), + } +} + +/// Get the search patterns to use for the given path +fn qpath_search_pat(path: &QPath<'_>) -> (Pat, Pat) { + match path { + QPath::Resolved(ty, path) => { + let start = if ty.is_some() { + Pat::Str("<") + } else { + path.segments + .first() + .map_or(Pat::Str(""), |seg| Pat::Sym(seg.ident.name)) + }; + let end = path.segments.last().map_or(Pat::Str(""), |seg| { + if seg.args.is_some() { + Pat::Str(">") + } else { + Pat::Sym(seg.ident.name) + } + }); + (start, end) + }, + QPath::TypeRelative(_, name) => (Pat::Str(""), Pat::Sym(name.ident.name)), + QPath::LangItem(..) => (Pat::Str(""), Pat::Str("")), + } +} + +/// Get the search patterns to use for the given expression +fn expr_search_pat(tcx: TyCtxt<'_>, e: &Expr<'_>) -> (Pat, Pat) { + match e.kind { + ExprKind::Box(e) => (Pat::Str("box"), expr_search_pat(tcx, e).1), + ExprKind::ConstBlock(_) => (Pat::Str("const"), Pat::Str("}")), + ExprKind::Tup([]) => (Pat::Str(")"), Pat::Str("(")), + ExprKind::Unary(UnOp::Deref, _) => (Pat::Str("*"), expr_search_pat(tcx, e).1), + ExprKind::Unary(UnOp::Not, _) => (Pat::Str("!"), expr_search_pat(tcx, e).1), + ExprKind::Unary(UnOp::Neg, _) => (Pat::Str("-"), expr_search_pat(tcx, e).1), + ExprKind::Lit(ref lit) => lit_search_pat(&lit.node), + ExprKind::Array(_) | ExprKind::Repeat(..) => (Pat::Str("["), Pat::Str("]")), + ExprKind::Call(e, []) | ExprKind::MethodCall(_, [e], _) => (expr_search_pat(tcx, e).0, Pat::Str("(")), + ExprKind::Call(first, [.., last]) + | ExprKind::MethodCall(_, [first, .., last], _) + | ExprKind::Binary(_, first, last) + | ExprKind::Tup([first, .., last]) + | ExprKind::Assign(first, last, _) + | ExprKind::AssignOp(_, first, last) => (expr_search_pat(tcx, first).0, expr_search_pat(tcx, last).1), + ExprKind::Tup([e]) | ExprKind::DropTemps(e) => expr_search_pat(tcx, e), + ExprKind::Cast(e, _) | ExprKind::Type(e, _) => (expr_search_pat(tcx, e).0, Pat::Str("")), + ExprKind::Let(let_expr) => (Pat::Str("let"), expr_search_pat(tcx, let_expr.init).1), + ExprKind::If(..) => (Pat::Str("if"), Pat::Str("}")), + ExprKind::Loop(_, Some(_), _, _) | ExprKind::Block(_, Some(_)) => (Pat::Str("'"), Pat::Str("}")), + ExprKind::Loop(_, None, LoopSource::Loop, _) => (Pat::Str("loop"), Pat::Str("}")), + ExprKind::Loop(_, None, LoopSource::While, _) => (Pat::Str("while"), Pat::Str("}")), + ExprKind::Loop(_, None, LoopSource::ForLoop, _) | ExprKind::Match(_, _, MatchSource::ForLoopDesugar) => { + (Pat::Str("for"), Pat::Str("}")) + }, + ExprKind::Match(_, _, MatchSource::Normal) => (Pat::Str("match"), Pat::Str("}")), + ExprKind::Match(e, _, MatchSource::TryDesugar) => (expr_search_pat(tcx, e).0, Pat::Str("?")), + ExprKind::Match(e, _, MatchSource::AwaitDesugar) | ExprKind::Yield(e, YieldSource::Await { .. }) => { + (expr_search_pat(tcx, e).0, Pat::Str("await")) + }, + ExprKind::Closure(&Closure { body, .. }) => (Pat::Str(""), expr_search_pat(tcx, &tcx.hir().body(body).value).1), + ExprKind::Block( + Block { + rules: BlockCheckMode::UnsafeBlock(UnsafeSource::UserProvided), + .. + }, + None, + ) => (Pat::Str("unsafe"), Pat::Str("}")), + ExprKind::Block(_, None) => (Pat::Str("{"), Pat::Str("}")), + ExprKind::Field(e, name) => (expr_search_pat(tcx, e).0, Pat::Sym(name.name)), + ExprKind::Index(e, _) => (expr_search_pat(tcx, e).0, Pat::Str("]")), + ExprKind::Path(ref path) => qpath_search_pat(path), + ExprKind::AddrOf(_, _, e) => (Pat::Str("&"), expr_search_pat(tcx, e).1), + ExprKind::Break(Destination { label: None, .. }, None) => (Pat::Str("break"), Pat::Str("break")), + ExprKind::Break(Destination { label: Some(name), .. }, None) => (Pat::Str("break"), Pat::Sym(name.ident.name)), + ExprKind::Break(_, Some(e)) => (Pat::Str("break"), expr_search_pat(tcx, e).1), + ExprKind::Continue(Destination { label: None, .. }) => (Pat::Str("continue"), Pat::Str("continue")), + ExprKind::Continue(Destination { label: Some(name), .. }) => (Pat::Str("continue"), Pat::Sym(name.ident.name)), + ExprKind::Ret(None) => (Pat::Str("return"), Pat::Str("return")), + ExprKind::Struct(path, _, _) => (qpath_search_pat(path).0, Pat::Str("}")), + ExprKind::Yield(e, YieldSource::Yield) => (Pat::Str("yield"), expr_search_pat(tcx, e).1), + _ => (Pat::Str(""), Pat::Str("")), + } +} + +/// Checks if the expression likely came from a proc-macro +pub fn is_expr_from_proc_macro(cx: &LateContext<'_>, e: &Expr<'_>) -> bool { + let (start_pat, end_pat) = expr_search_pat(cx.tcx, e); + !span_matches_pat(cx.sess(), e.span, start_pat, end_pat) +} + +/// Checks if the span actually refers to a match expression +pub fn is_span_match(cx: &LateContext<'_>, span: Span) -> bool { + span_matches_pat(cx.sess(), span, Pat::Str("match"), Pat::Str("}")) +} diff --git a/clippy_utils/src/lib.rs b/clippy_utils/src/lib.rs index 9ffbc73dc62..2d051e3a815 100644 --- a/clippy_utils/src/lib.rs +++ b/clippy_utils/src/lib.rs @@ -38,6 +38,7 @@ pub mod sym_helper; pub mod ast_utils; pub mod attrs; +mod check_proc_macro; pub mod comparisons; pub mod consts; pub mod diagnostics; @@ -58,6 +59,7 @@ pub mod usage; pub mod visitors; pub use self::attrs::*; +pub use self::check_proc_macro::{is_expr_from_proc_macro, is_span_match}; pub use self::hir_utils::{ both, count_eq, eq_expr_value, hash_expr, hash_stmt, over, HirEqInterExpr, SpanlessEq, SpanlessHash, }; diff --git a/clippy_utils/src/source.rs b/clippy_utils/src/source.rs index 1197fe914de..d85f591fb9a 100644 --- a/clippy_utils/src/source.rs +++ b/clippy_utils/src/source.rs @@ -11,24 +11,6 @@ use rustc_span::source_map::SourceMap; use rustc_span::{BytePos, Pos, Span, SpanData, SyntaxContext}; use std::borrow::Cow; -/// Checks if the span starts with the given text. This will return false if the span crosses -/// multiple files or if source is not available. -/// -/// This is used to check for proc macros giving unhelpful spans to things. -pub fn span_starts_with(cx: &T, span: Span, text: &str) -> bool { - fn helper(sm: &SourceMap, span: Span, text: &str) -> bool { - let pos = sm.lookup_byte_offset(span.lo()); - let Some(ref src) = pos.sf.src else { - return false; - }; - let end = span.hi() - pos.sf.start_pos; - src.get(pos.pos.0 as usize..end.0 as usize) - // Expression spans can include wrapping parenthesis. Remove them first. - .map_or(false, |s| s.trim_start_matches('(').starts_with(text)) - } - helper(cx.sess().source_map(), span, text) -} - /// Like `snippet_block`, but add braces if the expr is not an `ExprKind::Block`. /// Also takes an `Option` which can be put inside the braces. pub fn expr_block<'a, T: LintContext>( diff --git a/tests/ui/unit_arg.rs b/tests/ui/unit_arg.rs index 38be87bddf1..7bf3adc07ac 100644 --- a/tests/ui/unit_arg.rs +++ b/tests/ui/unit_arg.rs @@ -1,3 +1,5 @@ +// aux-build: proc_macro_with_span.rs + #![warn(clippy::unit_arg)] #![allow( clippy::no_effect, @@ -8,9 +10,13 @@ clippy::or_fun_call, clippy::needless_question_mark, clippy::self_named_constructors, - clippy::let_unit_value + clippy::let_unit_value, + clippy::never_loop )] +extern crate proc_macro_with_span; + +use proc_macro_with_span::with_span; use std::fmt::Debug; fn foo(t: T) { @@ -127,6 +133,10 @@ fn returning_expr() -> Option<()> { fn taking_multiple_units(a: (), b: ()) {} +fn proc_macro() { + with_span!(span taking_multiple_units(unsafe { (); }, 'x: loop { break 'x (); })); +} + fn main() { bad(); ok(); diff --git a/tests/ui/unit_arg.stderr b/tests/ui/unit_arg.stderr index 11cfe66a30e..1de9d44bb0d 100644 --- a/tests/ui/unit_arg.stderr +++ b/tests/ui/unit_arg.stderr @@ -1,5 +1,5 @@ error: passing a unit value to a function - --> $DIR/unit_arg.rs:57:5 + --> $DIR/unit_arg.rs:63:5 | LL | / foo({ LL | | 1; @@ -20,7 +20,7 @@ LL ~ foo(()); | error: passing a unit value to a function - --> $DIR/unit_arg.rs:60:5 + --> $DIR/unit_arg.rs:66:5 | LL | foo(foo(1)); | ^^^^^^^^^^^ @@ -32,7 +32,7 @@ LL ~ foo(()); | error: passing a unit value to a function - --> $DIR/unit_arg.rs:61:5 + --> $DIR/unit_arg.rs:67:5 | LL | / foo({ LL | | foo(1); @@ -54,7 +54,7 @@ LL ~ foo(()); | error: passing a unit value to a function - --> $DIR/unit_arg.rs:66:5 + --> $DIR/unit_arg.rs:72:5 | LL | / b.bar({ LL | | 1; @@ -74,7 +74,7 @@ LL ~ b.bar(()); | error: passing unit values to a function - --> $DIR/unit_arg.rs:69:5 + --> $DIR/unit_arg.rs:75:5 | LL | taking_multiple_units(foo(0), foo(1)); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ @@ -87,7 +87,7 @@ LL ~ taking_multiple_units((), ()); | error: passing unit values to a function - --> $DIR/unit_arg.rs:70:5 + --> $DIR/unit_arg.rs:76:5 | LL | / taking_multiple_units(foo(0), { LL | | foo(1); @@ -110,7 +110,7 @@ LL ~ taking_multiple_units((), ()); | error: passing unit values to a function - --> $DIR/unit_arg.rs:74:5 + --> $DIR/unit_arg.rs:80:5 | LL | / taking_multiple_units( LL | | { @@ -146,7 +146,7 @@ LL ~ ); | error: passing a unit value to a function - --> $DIR/unit_arg.rs:85:13 + --> $DIR/unit_arg.rs:91:13 | LL | None.or(Some(foo(2))); | ^^^^^^^^^^^^ @@ -160,7 +160,7 @@ LL ~ }); | error: passing a unit value to a function - --> $DIR/unit_arg.rs:88:5 + --> $DIR/unit_arg.rs:94:5 | LL | foo(foo(())); | ^^^^^^^^^^^^ @@ -172,7 +172,7 @@ LL ~ foo(()); | error: passing a unit value to a function - --> $DIR/unit_arg.rs:125:5 + --> $DIR/unit_arg.rs:131:5 | LL | Some(foo(1)) | ^^^^^^^^^^^^