Auto merge of rust-lang#12394 - CBSpeir:issue-12390-refactor, r=Alexe…

…ndoo

Refactor lints in clippy_lints::attrs into separate submodules/files

This pull request contains the changes requested in issue rust-lang#12390.

changelog: none

clippy_lints/src/attrs/allow_attributes_without_reason.rs

@@ -0,0 +1,37 @@
+use super::{Attribute, ALLOW_ATTRIBUTES_WITHOUT_REASON};
+use clippy_utils::diagnostics::span_lint_and_help;
+use clippy_utils::is_from_proc_macro;
+use rustc_ast::{MetaItemKind, NestedMetaItem};
+use rustc_lint::{LateContext, LintContext};
+use rustc_middle::lint::in_external_macro;
+use rustc_span::sym;
+use rustc_span::symbol::Symbol;
+
+pub(super) fn check<'cx>(cx: &LateContext<'cx>, name: Symbol, items: &[NestedMetaItem], attr: &'cx Attribute) {
+    // Check for the feature
+    if !cx.tcx.features().lint_reasons {
+        return;
+    }
+
+    // Check if the reason is present
+    if let Some(item) = items.last().and_then(NestedMetaItem::meta_item)
+        && let MetaItemKind::NameValue(_) = &item.kind
+        && item.path == sym::reason
+    {
+        return;
+    }
+
+    // Check if the attribute is in an external macro and therefore out of the developer's control
+    if in_external_macro(cx.sess(), attr.span) || is_from_proc_macro(cx, &attr) {
+        return;
+    }
+
+    span_lint_and_help(
+        cx,
+        ALLOW_ATTRIBUTES_WITHOUT_REASON,
+        attr.span,
+        &format!("`{}` attribute without specifying a reason", name.as_str()),
+        None,
+        "try adding a reason at the end with `, reason = \"..\"`",
+    );
+}

clippy_lints/src/attrs/blanket_clippy_restriction_lints.rs

@@ -0,0 +1,44 @@
+use super::utils::extract_clippy_lint;
+use super::BLANKET_CLIPPY_RESTRICTION_LINTS;
+use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_then};
+use rustc_ast::NestedMetaItem;
+use rustc_lint::{LateContext, Level, LintContext};
+use rustc_span::symbol::Symbol;
+use rustc_span::{sym, DUMMY_SP};
+
+pub(super) fn check(cx: &LateContext<'_>, name: Symbol, items: &[NestedMetaItem]) {
+    for lint in items {
+        if let Some(lint_name) = extract_clippy_lint(lint) {
+            if lint_name.as_str() == "restriction" && name != sym::allow {
+                span_lint_and_help(
+                    cx,
+                    BLANKET_CLIPPY_RESTRICTION_LINTS,
+                    lint.span(),
+                    "`clippy::restriction` is not meant to be enabled as a group",
+                    None,
+                    "enable the restriction lints you need individually",
+                );
+            }
+        }
+    }
+}
+
+pub(super) fn check_command_line(cx: &LateContext<'_>) {
+    for (name, level) in &cx.sess().opts.lint_opts {
+        if name == "clippy::restriction" && *level > Level::Allow {
+            span_lint_and_then(
+                cx,
+                BLANKET_CLIPPY_RESTRICTION_LINTS,
+                DUMMY_SP,
+                "`clippy::restriction` is not meant to be enabled as a group",
+                |diag| {
+                    diag.note(format!(
+                        "because of the command line `--{} clippy::restriction`",
+                        level.as_str()
+                    ));
+                    diag.help("enable the restriction lints you need individually");
+                },
+            );
+        }
+    }
+}

clippy_lints/src/attrs/deprecated_cfg_attr.rs

@@ -0,0 +1,87 @@
+use super::{unnecessary_clippy_cfg, Attribute, DEPRECATED_CFG_ATTR, DEPRECATED_CLIPPY_CFG_ATTR};
+use clippy_config::msrvs::{self, Msrv};
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use rustc_ast::AttrStyle;
+use rustc_errors::Applicability;
+use rustc_lint::EarlyContext;
+use rustc_span::sym;
+
+pub(super) fn check(cx: &EarlyContext<'_>, attr: &Attribute, msrv: &Msrv) {
+    // check cfg_attr
+    if attr.has_name(sym::cfg_attr)
+        && let Some(items) = attr.meta_item_list()
+        && items.len() == 2
+        && let Some(feature_item) = items[0].meta_item()
+    {
+        // check for `rustfmt`
+        if feature_item.has_name(sym::rustfmt)
+            && msrv.meets(msrvs::TOOL_ATTRIBUTES)
+            // check for `rustfmt_skip` and `rustfmt::skip`
+            && let Some(skip_item) = &items[1].meta_item()
+            && (skip_item.has_name(sym!(rustfmt_skip))
+                || skip_item
+                    .path
+                    .segments
+                    .last()
+                    .expect("empty path in attribute")
+                    .ident
+                    .name
+                    == sym::skip)
+            // Only lint outer attributes, because custom inner attributes are unstable
+            // Tracking issue: https://github.com/rust-lang/rust/issues/54726
+            && attr.style == AttrStyle::Outer
+        {
+            span_lint_and_sugg(
+                cx,
+                DEPRECATED_CFG_ATTR,
+                attr.span,
+                "`cfg_attr` is deprecated for rustfmt and got replaced by tool attributes",
+                "use",
+                "#[rustfmt::skip]".to_string(),
+                Applicability::MachineApplicable,
+            );
+        } else {
+            check_deprecated_cfg_recursively(cx, feature_item);
+            if let Some(behind_cfg_attr) = items[1].meta_item() {
+                unnecessary_clippy_cfg::check(cx, feature_item, behind_cfg_attr, attr);
+            }
+        }
+    }
+}
+
+pub(super) fn check_clippy(cx: &EarlyContext<'_>, attr: &Attribute) {
+    if attr.has_name(sym::cfg)
+        && let Some(list) = attr.meta_item_list()
+    {
+        for item in list.iter().filter_map(|item| item.meta_item()) {
+            check_deprecated_cfg_recursively(cx, item);
+        }
+    }
+}
+
+fn check_deprecated_cfg_recursively(cx: &EarlyContext<'_>, attr: &rustc_ast::MetaItem) {
+    if let Some(ident) = attr.ident() {
+        if ["any", "all", "not"].contains(&ident.name.as_str()) {
+            let Some(list) = attr.meta_item_list() else { return };
+            for item in list.iter().filter_map(|item| item.meta_item()) {
+                check_deprecated_cfg_recursively(cx, item);
+            }
+        } else {
+            check_cargo_clippy_attr(cx, attr);
+        }
+    }
+}
+
+fn check_cargo_clippy_attr(cx: &EarlyContext<'_>, item: &rustc_ast::MetaItem) {
+    if item.has_name(sym::feature) && item.value_str().is_some_and(|v| v.as_str() == "cargo-clippy") {
+        span_lint_and_sugg(
+            cx,
+            DEPRECATED_CLIPPY_CFG_ATTR,
+            item.span,
+            "`feature = \"cargo-clippy\"` was replaced by `clippy`",
+            "replace with",
+            "clippy".to_string(),
+            Applicability::MachineApplicable,
+        );
+    }
+}

clippy_lints/src/attrs/deprecated_semver.rs

@@ -0,0 +1,20 @@
+use super::DEPRECATED_SEMVER;
+use clippy_utils::diagnostics::span_lint;
+use rustc_ast::{LitKind, MetaItemLit};
+use rustc_lint::LateContext;
+use rustc_span::Span;
+use semver::Version;
+
+pub(super) fn check(cx: &LateContext<'_>, span: Span, lit: &MetaItemLit) {
+    if let LitKind::Str(is, _) = lit.kind {
+        if is.as_str() == "TBD" || Version::parse(is.as_str()).is_ok() {
+            return;
+        }
+    }
+    span_lint(
+        cx,
+        DEPRECATED_SEMVER,
+        span,
+        "the since field must contain a semver-compliant version",
+    );
+}

clippy_lints/src/attrs/empty_line_after.rs

@@ -0,0 +1,52 @@
+use super::{EMPTY_LINE_AFTER_DOC_COMMENTS, EMPTY_LINE_AFTER_OUTER_ATTR};
+use clippy_utils::diagnostics::span_lint;
+use clippy_utils::source::{is_present_in_source, snippet_opt, without_block_comments};
+use rustc_ast::{AttrKind, AttrStyle};
+use rustc_lint::EarlyContext;
+use rustc_span::Span;
+
+/// Check for empty lines after outer attributes.
+///
+/// Attributes and documentation comments are both considered outer attributes
+/// by the AST. However, the average user likely considers them to be different.
+/// Checking for empty lines after each of these attributes is split into two different
+/// lints but can share the same logic.
+pub(super) fn check(cx: &EarlyContext<'_>, item: &rustc_ast::Item) {
+    let mut iter = item.attrs.iter().peekable();
+    while let Some(attr) = iter.next() {
+        if (matches!(attr.kind, AttrKind::Normal(..)) || matches!(attr.kind, AttrKind::DocComment(..)))
+            && attr.style == AttrStyle::Outer
+            && is_present_in_source(cx, attr.span)
+        {
+            let begin_of_attr_to_item = Span::new(attr.span.lo(), item.span.lo(), item.span.ctxt(), item.span.parent());
+            let end_of_attr_to_next_attr_or_item = Span::new(
+                attr.span.hi(),
+                iter.peek().map_or(item.span.lo(), |next_attr| next_attr.span.lo()),
+                item.span.ctxt(),
+                item.span.parent(),
+            );
+
+            if let Some(snippet) = snippet_opt(cx, end_of_attr_to_next_attr_or_item) {
+                let lines = snippet.split('\n').collect::<Vec<_>>();
+                let lines = without_block_comments(lines);
+
+                if lines.iter().filter(|l| l.trim().is_empty()).count() > 2 {
+                    let (lint_msg, lint_type) = match attr.kind {
+                        AttrKind::DocComment(..) => (
+                            "found an empty line after a doc comment. \
+                            Perhaps you need to use `//!` to make a comment on a module, remove the empty line, or make a regular comment with `//`?",
+                            EMPTY_LINE_AFTER_DOC_COMMENTS,
+                        ),
+                        AttrKind::Normal(..) => (
+                            "found an empty line after an outer attribute. \
+                            Perhaps you forgot to add a `!` to make it an inner attribute?",
+                            EMPTY_LINE_AFTER_OUTER_ATTR,
+                        ),
+                    };
+
+                    span_lint(cx, lint_type, begin_of_attr_to_item, lint_msg);
+                }
+            }
+        }
+    }
+}

clippy_lints/src/attrs/inline_always.rs

@@ -0,0 +1,29 @@
+use super::utils::is_word;
+use super::INLINE_ALWAYS;
+use clippy_utils::diagnostics::span_lint;
+use rustc_ast::Attribute;
+use rustc_lint::LateContext;
+use rustc_span::symbol::Symbol;
+use rustc_span::{sym, Span};
+
+pub(super) fn check(cx: &LateContext<'_>, span: Span, name: Symbol, attrs: &[Attribute]) {
+    if span.from_expansion() {
+        return;
+    }
+
+    for attr in attrs {
+        if let Some(values) = attr.meta_item_list() {
+            if values.len() != 1 || !attr.has_name(sym::inline) {
+                continue;
+            }
+            if is_word(&values[0], sym::always) {
+                span_lint(
+                    cx,
+                    INLINE_ALWAYS,
+                    attr.span,
+                    &format!("you have declared `#[inline(always)]` on `{name}`. This is usually a bad idea"),
+                );
+            }
+        }
+    }
+}

clippy_lints/src/attrs/maybe_misused_cfg.rs

@@ -0,0 +1,51 @@
+use super::{Attribute, MAYBE_MISUSED_CFG};
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use rustc_ast::{MetaItemKind, NestedMetaItem};
+use rustc_errors::Applicability;
+use rustc_lint::EarlyContext;
+use rustc_span::sym;
+
+pub(super) fn check(cx: &EarlyContext<'_>, attr: &Attribute) {
+    if attr.has_name(sym::cfg)
+        && let Some(items) = attr.meta_item_list()
+    {
+        check_nested_misused_cfg(cx, &items);
+    }
+}
+
+fn check_nested_misused_cfg(cx: &EarlyContext<'_>, items: &[NestedMetaItem]) {
+    for item in items {
+        if let NestedMetaItem::MetaItem(meta) = item {
+            if let Some(ident) = meta.ident()
+                && ident.name.as_str() == "features"
+                && let Some(val) = meta.value_str()
+            {
+                span_lint_and_sugg(
+                    cx,
+                    MAYBE_MISUSED_CFG,
+                    meta.span,
+                    "'feature' may be misspelled as 'features'",
+                    "did you mean",
+                    format!("feature = \"{val}\""),
+                    Applicability::MaybeIncorrect,
+                );
+            }
+            if let MetaItemKind::List(list) = &meta.kind {
+                check_nested_misused_cfg(cx, list);
+            // If this is not a list, then we check for `cfg(test)`.
+            } else if let Some(ident) = meta.ident()
+                && matches!(ident.name.as_str(), "tests" | "Test")
+            {
+                span_lint_and_sugg(
+                    cx,
+                    MAYBE_MISUSED_CFG,
+                    meta.span,
+                    &format!("'test' may be misspelled as '{}'", ident.name.as_str()),
+                    "did you mean",
+                    "test".to_string(),
+                    Applicability::MaybeIncorrect,
+                );
+            }
+        }
+    }
+}