Auto merge of rust-lang#8694 - Jarcho:check_proc_macro, r=xFrednet

More proc-macro detection

fixes rust-lang#6514
fixes rust-lang#8683
fixes rust-lang#6858
fixes rust-lang#6594

This is a more general way of checking if an expression comes from a macro and could be trivially applied to other lints. Ideally this would be fixed in rustc's proc-macro api, but I don't see that happening any time soon.

changelog: FPs: [`unit_arg`] [`default_trait_access`] [`missing_docs_in_private_items`]: No longer trigger in code generated from proc-macros.

clippy_lints/src/default.rs

@@ -1,7 +1,9 @@
 use clippy_utils::diagnostics::{span_lint_and_note, span_lint_and_sugg};
 use clippy_utils::source::snippet_with_macro_callsite;
 use clippy_utils::ty::{has_drop, is_copy};
-use clippy_utils::{any_parent_is_automatically_derived, contains_name, get_parent_expr, match_def_path, paths};
+use clippy_utils::{
+    any_parent_is_automatically_derived, contains_name, get_parent_expr, is_from_proc_macro, match_def_path, paths,
+};
 use if_chain::if_chain;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::Applicability;
@@ -94,6 +96,7 @@ impl<'tcx> LateLintPass<'tcx> for Default {
             if let QPath::Resolved(None, _path) = qpath;
             let expr_ty = cx.typeck_results().expr_ty(expr);
             if let ty::Adt(def, ..) = expr_ty.kind();
+            if !is_from_proc_macro(cx, expr);
             then {
                 // TODO: Work out a way to put "whatever the imported way of referencing
                 // this type in this file" rather than a fully-qualified type.

clippy_lints/src/formatting.rs

@@ -1,4 +1,5 @@
 use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_note};
+use clippy_utils::is_span_if;
 use clippy_utils::source::snippet_opt;
 use if_chain::if_chain;
 use rustc_ast::ast::{BinOpKind, Block, Expr, ExprKind, StmtKind, UnOp};
@@ -297,12 +298,11 @@ fn check_array(cx: &EarlyContext<'_>, expr: &Expr) {
 fn check_missing_else(cx: &EarlyContext<'_>, first: &Expr, second: &Expr) {
     if_chain! {
         if !first.span.from_expansion() && !second.span.from_expansion();
-        if let ExprKind::If(cond_expr, ..) = &first.kind;
+        if matches!(first.kind, ExprKind::If(..));
         if is_block(second) || is_if(second);
 
         // Proc-macros can give weird spans. Make sure this is actually an `if`.
-        if let Some(if_snip) = snippet_opt(cx, first.span.until(cond_expr.span));
-        if if_snip.starts_with("if");
+        if is_span_if(cx, first.span);
 
         // If there is a line break between the two expressions, don't lint.
         // If there is a non-whitespace character, this span came from a proc-macro.

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) {

clippy_lints/src/missing_doc.rs

@@ -7,6 +7,7 @@
 
 use clippy_utils::attrs::is_doc_hidden;
 use clippy_utils::diagnostics::span_lint;
+use clippy_utils::is_from_proc_macro;
 use if_chain::if_chain;
 use rustc_ast::ast::{self, MetaItem, MetaItemKind};
 use rustc_hir as hir;
@@ -158,14 +159,18 @@ impl<'tcx> LateLintPass<'tcx> for MissingDoc {
         let (article, desc) = cx.tcx.article_and_description(it.def_id.to_def_id());
 
         let attrs = cx.tcx.hir().attrs(it.hir_id());
-        self.check_missing_docs_attrs(cx, attrs, it.span, article, desc);
+        if !is_from_proc_macro(cx, it) {
+            self.check_missing_docs_attrs(cx, attrs, it.span, article, desc);
+        }
     }
 
     fn check_trait_item(&mut self, cx: &LateContext<'tcx>, trait_item: &'tcx hir::TraitItem<'_>) {
         let (article, desc) = cx.tcx.article_and_description(trait_item.def_id.to_def_id());
 
         let attrs = cx.tcx.hir().attrs(trait_item.hir_id());
-        self.check_missing_docs_attrs(cx, attrs, trait_item.span, article, desc);
+        if !is_from_proc_macro(cx, trait_item) {
+            self.check_missing_docs_attrs(cx, attrs, trait_item.span, article, desc);
+        }
     }
 
     fn check_impl_item(&mut self, cx: &LateContext<'tcx>, impl_item: &'tcx hir::ImplItem<'_>) {
@@ -181,18 +186,24 @@ impl<'tcx> LateLintPass<'tcx> for MissingDoc {
 
         let (article, desc) = cx.tcx.article_and_description(impl_item.def_id.to_def_id());
         let attrs = cx.tcx.hir().attrs(impl_item.hir_id());
-        self.check_missing_docs_attrs(cx, attrs, impl_item.span, article, desc);
+        if !is_from_proc_macro(cx, impl_item) {
+            self.check_missing_docs_attrs(cx, attrs, impl_item.span, article, desc);
+        }
     }
 
     fn check_field_def(&mut self, cx: &LateContext<'tcx>, sf: &'tcx hir::FieldDef<'_>) {
         if !sf.is_positional() {
             let attrs = cx.tcx.hir().attrs(sf.hir_id);
-            self.check_missing_docs_attrs(cx, attrs, sf.span, "a", "struct field");
+            if !is_from_proc_macro(cx, sf) {
+                self.check_missing_docs_attrs(cx, attrs, sf.span, "a", "struct field");
+            }
         }
     }
 
     fn check_variant(&mut self, cx: &LateContext<'tcx>, v: &'tcx hir::Variant<'_>) {
         let attrs = cx.tcx.hir().attrs(v.id);
-        self.check_missing_docs_attrs(cx, attrs, v.span, "a", "variant");
+        if !is_from_proc_macro(cx, v) {
+            self.check_missing_docs_attrs(cx, attrs, v.span, "a", "variant");
+        }
     }
 }

clippy_lints/src/unit_types/mod.rs

@@ -103,7 +103,7 @@ impl<'tcx> LateLintPass<'tcx> for UnitTypes {
         let_unit_value::check(cx, local);
     }
 
-    fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
+    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
         unit_cmp::check(cx, expr);
         unit_arg::check(cx, expr);
     }

clippy_lints/src/unit_types/unit_arg.rs

@@ -1,4 +1,5 @@
 use clippy_utils::diagnostics::span_lint_and_then;
+use clippy_utils::is_from_proc_macro;
 use clippy_utils::source::{indent_of, reindent_multiline, snippet_opt};
 use if_chain::if_chain;
 use rustc_errors::Applicability;
@@ -7,7 +8,7 @@ use rustc_lint::LateContext;
 
 use super::{utils, UNIT_ARG};
 
-pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>) {
+pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
     if expr.span.from_expansion() {
         return;
     }
@@ -44,7 +45,7 @@ pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>) {
                     }
                 })
                 .collect::<Vec<_>>();
-            if !args_to_recover.is_empty() {
+            if !args_to_recover.is_empty() && !is_from_proc_macro(cx, expr) {
                 lint_unit_args(cx, expr, &args_to_recover);
             }
         },