Add an internal lint that warns when accessing untracked data

Author: Nadrieril

compiler/rustc_data_structures/src/steal.rs

@@ -57,6 +57,7 @@ impl<T> Steal<T> {
     ///
     /// This should not be used within rustc as it leaks information not tracked
     /// by the query system, breaking incremental compilation.
+    #[cfg_attr(not(bootstrap), rustc_lint_untracked_query_information)]
     pub fn is_stolen(&self) -> bool {
         self.value.borrow().is_none()
     }

compiler/rustc_feature/src/builtin_attrs.rs

@@ -792,6 +792,12 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
         rustc_lint_query_instability, Normal, template!(Word),
         WarnFollowing, EncodeCrossCrate::Yes, INTERNAL_UNSTABLE
     ),
+    // Used by the `rustc::untracked_query_information` lint to warn methods which
+    // might not be stable during incremental compilation.
+    rustc_attr!(
+        rustc_lint_untracked_query_information, Normal, template!(Word),
+        WarnFollowing, EncodeCrossCrate::Yes, INTERNAL_UNSTABLE
+    ),
     // Used by the `rustc::diagnostic_outside_of_impl` lints to assist in changes to diagnostic
     // APIs. Any function with this attribute will be checked by that lint.
     rustc_attr!(

compiler/rustc_lint/messages.ftl

@@ -690,6 +690,9 @@ lint_ptr_null_checks_ref = references are not nullable, so checking them for nul
 lint_query_instability = using `{$query}` can result in unstable query results
     .note = if you believe this case to be fine, allow this lint and add a comment explaining your rationale
 
+lint_query_untracked = `{$method}` accesses information that is not tracked by the query system
+    .note = if you believe this case to be fine, allow this lint and add a comment explaining your rationale
+
 lint_range_endpoint_out_of_range = range endpoint is out of range for `{$ty}`
 
 lint_range_use_inclusive_range = use an inclusive range instead

compiler/rustc_lint/src/internal.rs

@@ -17,8 +17,8 @@ use tracing::debug;
 
 use crate::lints::{
     BadOptAccessDiag, DefaultHashTypesDiag, DiagOutOfImpl, LintPassByHand, NonExistentDocKeyword,
-    NonGlobImportTypeIrInherent, QueryInstability, SpanUseEqCtxtDiag, TyQualified, TykindDiag,
-    TykindKind, UntranslatableDiag,
+    NonGlobImportTypeIrInherent, QueryInstability, QueryUntracked, SpanUseEqCtxtDiag, TyQualified,
+    TykindDiag, TykindKind, UntranslatableDiag,
 };
 use crate::{EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext};
 
@@ -88,7 +88,18 @@ declare_tool_lint! {
     report_in_external_macro: true
 }
 
-declare_lint_pass!(QueryStability => [POTENTIAL_QUERY_INSTABILITY]);
+declare_tool_lint! {
+    /// The `untracked_query_information` lint detects use of methods which leak information not
+    /// tracked by the query system, such as whether a `Steal<T>` value has already been stolen. In
+    /// order not to break incremental compilation, such methods must be used very carefully or not
+    /// at all.
+    pub rustc::UNTRACKED_QUERY_INFORMATION,
+    Allow,
+    "require explicit opt-in when accessing information not tracked by the query system",
+    report_in_external_macro: true
+}
+
+declare_lint_pass!(QueryStability => [POTENTIAL_QUERY_INSTABILITY, UNTRACKED_QUERY_INFORMATION]);
 
 impl LateLintPass<'_> for QueryStability {
     fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
@@ -102,6 +113,13 @@ impl LateLintPass<'_> for QueryStability {
                     QueryInstability { query: cx.tcx.item_name(def_id) },
                 );
             }
+            if cx.tcx.has_attr(def_id, sym::rustc_lint_untracked_query_information) {
+                cx.emit_span_lint(
+                    UNTRACKED_QUERY_INFORMATION,
+                    span,
+                    QueryUntracked { method: cx.tcx.item_name(def_id) },
+                );
+            }
         }
     }
 }

compiler/rustc_lint/src/lib.rs

@@ -604,6 +604,7 @@ fn register_internals(store: &mut LintStore) {
         vec![
             LintId::of(DEFAULT_HASH_TYPES),
             LintId::of(POTENTIAL_QUERY_INSTABILITY),
+            LintId::of(UNTRACKED_QUERY_INFORMATION),
             LintId::of(USAGE_OF_TY_TYKIND),
             LintId::of(PASS_BY_VALUE),
             LintId::of(LINT_PASS_IMPL_WITHOUT_MACRO),

compiler/rustc_lint/src/lints.rs

@@ -894,6 +894,13 @@ pub struct QueryInstability {
     pub query: Symbol,
 }
 
+#[derive(LintDiagnostic)]
+#[diag(lint_query_untracked)]
+#[note]
+pub struct QueryUntracked {
+    pub method: Symbol,
+}
+
 #[derive(LintDiagnostic)]
 #[diag(lint_span_use_eq_ctxt)]
 pub struct SpanUseEqCtxtDiag;

compiler/rustc_passes/src/check_attr.rs

@@ -125,7 +125,9 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 [sym::inline, ..] => self.check_inline(hir_id, attr, span, target),
                 [sym::coverage, ..] => self.check_coverage(attr, span, target),
                 [sym::optimize, ..] => self.check_optimize(hir_id, attr, target),
-                [sym::no_sanitize, ..] => self.check_no_sanitize(hir_id, attr, span, target),
+                [sym::no_sanitize, ..] => {
+                    self.check_applied_to_fn_or_method(hir_id, attr, span, target)
+                }
                 [sym::non_exhaustive, ..] => self.check_non_exhaustive(hir_id, attr, span, target),
                 [sym::marker, ..] => self.check_marker(hir_id, attr, span, target),
                 [sym::target_feature, ..] => {
@@ -166,10 +168,13 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                     self.check_rustc_legacy_const_generics(hir_id, attr, span, target, item)
                 }
                 [sym::rustc_lint_query_instability, ..] => {
-                    self.check_rustc_lint_query_instability(hir_id, attr, span, target)
+                    self.check_applied_to_fn_or_method(hir_id, attr, span, target)
+                }
+                [sym::rustc_lint_untracked_query_information, ..] => {
+                    self.check_applied_to_fn_or_method(hir_id, attr, span, target)
                 }
                 [sym::rustc_lint_diagnostics, ..] => {
-                    self.check_rustc_lint_diagnostics(hir_id, attr, span, target)
+                    self.check_applied_to_fn_or_method(hir_id, attr, span, target)
                 }
                 [sym::rustc_lint_opt_ty, ..] => self.check_rustc_lint_opt_ty(attr, span, target),
                 [sym::rustc_lint_opt_deny_field_access, ..] => {
@@ -451,11 +456,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
     }
 
-    /// Checks that `#[no_sanitize(..)]` is applied to a function or method.
-    fn check_no_sanitize(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
-        self.check_applied_to_fn_or_method(hir_id, attr, span, target)
-    }
-
     fn check_generic_attr(
         &self,
         hir_id: HirId,
@@ -1603,30 +1603,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
     }
 
-    /// Checks that the `#[rustc_lint_query_instability]` attribute is only applied to a function
-    /// or method.
-    fn check_rustc_lint_query_instability(
-        &self,
-        hir_id: HirId,
-        attr: &Attribute,
-        span: Span,
-        target: Target,
-    ) {
-        self.check_applied_to_fn_or_method(hir_id, attr, span, target)
-    }
-
-    /// Checks that the `#[rustc_lint_diagnostics]` attribute is only applied to a function or
-    /// method.
-    fn check_rustc_lint_diagnostics(
-        &self,
-        hir_id: HirId,
-        attr: &Attribute,
-        span: Span,
-        target: Target,
-    ) {
-        self.check_applied_to_fn_or_method(hir_id, attr, span, target)
-    }
-
     /// Checks that the `#[rustc_lint_opt_ty]` attribute is only applied to a struct.
     fn check_rustc_lint_opt_ty(&self, attr: &Attribute, span: Span, target: Target) {
         match target {

compiler/rustc_span/src/symbol.rs

@@ -1644,6 +1644,7 @@ symbols! {
         rustc_lint_opt_deny_field_access,
         rustc_lint_opt_ty,
         rustc_lint_query_instability,
+        rustc_lint_untracked_query_information,
         rustc_macro_transparency,
         rustc_main,
         rustc_mir,

src/tools/rust-analyzer/crates/hir-expand/src/inert_attr_macro.rs

@@ -464,6 +464,9 @@ pub const INERT_ATTRIBUTES: &[BuiltinAttribute] = &[
     // Used by the `rustc::potential_query_instability` lint to warn methods which
     // might not be stable during incremental compilation.
     rustc_attr!(rustc_lint_query_instability, Normal, template!(Word), WarnFollowing, INTERNAL_UNSTABLE),
+    // Used by the `rustc::untracked_query_information` lint to warn methods which
+    // might break incremental compilation.
+    rustc_attr!(rustc_lint_untracked_query_information, Normal, template!(Word), WarnFollowing, INTERNAL_UNSTABLE),
     // Used by the `rustc::untranslatable_diagnostic` and `rustc::diagnostic_outside_of_impl` lints
     // to assist in changes to diagnostic APIs.
     rustc_attr!(rustc_lint_diagnostics, Normal, template!(Word), WarnFollowing, INTERNAL_UNSTABLE),

tests/ui-fulldeps/internal-lints/query_completeness.rs

@@ -0,0 +1,14 @@
+//@ compile-flags: -Z unstable-options
+#![feature(rustc_private)]
+#![deny(rustc::untracked_query_information)]
+
+extern crate rustc_data_structures;
+
+use rustc_data_structures::steal::Steal;
+
+fn use_steal(x: Steal<()>) {
+    let _ = x.is_stolen();
+    //~^ ERROR `is_stolen` accesses information that is not tracked by the query system
+}
+
+fn main() {}

tests/ui-fulldeps/internal-lints/query_completeness.stderr

@@ -0,0 +1,15 @@
+error: `is_stolen` accesses information that is not tracked by the query system
+  --> $DIR/query_completeness.rs:10:15
+   |
+LL |     let _ = x.is_stolen();
+   |               ^^^^^^^^^
+   |
+   = note: if you believe this case to be fine, allow this lint and add a comment explaining your rationale
+note: the lint level is defined here
+  --> $DIR/query_completeness.rs:3:9
+   |
+LL | #![deny(rustc::untracked_query_information)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+