Supress unhelpful diagnostics for unresolved top level attributes

Author: chenyukang

compiler/rustc_errors/src/lib.rs

@@ -509,6 +509,7 @@ pub enum StashKey {
     MaybeForgetReturn,
     /// Query cycle detected, stashing in favor of a better error.
     Cycle,
+    MacroResolutionError,
 }
 
 fn default_track_diagnostic(diag: Diagnostic, f: &mut dyn FnMut(Diagnostic)) {

compiler/rustc_passes/src/check_attr.rs

@@ -5,8 +5,11 @@
 //! item.
 
 use crate::{errors, fluent_generated as fluent};
-use rustc_ast::{ast, AttrStyle, Attribute, LitKind, MetaItemKind, MetaItemLit, NestedMetaItem};
+use rustc_ast::{
+    ast, AttrKind, AttrStyle, Attribute, LitKind, MetaItemKind, MetaItemLit, NestedMetaItem,
+};
 use rustc_data_structures::fx::FxHashMap;
+use rustc_errors::StashKey;
 use rustc_errors::{Applicability, DiagCtxt, IntoDiagnosticArg, MultiSpan};
 use rustc_feature::{AttributeDuplicates, AttributeType, BuiltinAttribute, BUILTIN_ATTRIBUTE_MAP};
 use rustc_hir as hir;
@@ -2530,6 +2533,13 @@ fn check_invalid_crate_level_attr(tcx: TyCtxt<'_>, attrs: &[Attribute]) {
         if attr.style == AttrStyle::Inner {
             for attr_to_check in ATTRS_TO_CHECK {
                 if attr.has_name(*attr_to_check) {
+                    if let AttrKind::Normal(ref p) = attr.kind
+                        && let Some(diag) = tcx
+                            .dcx()
+                            .steal_diagnostic(p.item.path.span, StashKey::MacroResolutionError)
+                    {
+                        diag.cancel();
+                    }
                     let item = tcx
                         .hir()
                         .items()

compiler/rustc_resolve/src/macros.rs

@@ -1,9 +1,9 @@
 //! A bunch of methods and structures more or less related to resolving macros and
 //! interface provided by `Resolver` to macro expander.
 
+use crate::errors::CannotDetermineMacroResolution;
 use crate::errors::{
-    self, AddAsNonDerive, CannotDetermineMacroResolution, CannotFindIdentInThisScope,
-    MacroExpectedFound, RemoveSurroundingDerive,
+    self, AddAsNonDerive, CannotFindIdentInThisScope, MacroExpectedFound, RemoveSurroundingDerive,
 };
 use crate::Namespace::*;
 use crate::{BuiltinMacroState, Determinacy, MacroData};
@@ -15,6 +15,7 @@ use rustc_ast_pretty::pprust;
 use rustc_attr::StabilityLevel;
 use rustc_data_structures::intern::Interned;
 use rustc_data_structures::sync::Lrc;
+use rustc_errors::StashKey::MacroResolutionError;
 use rustc_errors::{struct_span_code_err, Applicability};
 use rustc_expand::base::{Annotatable, DeriveResolutions, Indeterminate, ResolverExpand};
 use rustc_expand::base::{SyntaxExtension, SyntaxExtensionKind};
@@ -703,21 +704,21 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                     // situations should be reported as errors, so this is a bug.
                     this.dcx().span_delayed_bug(span, "inconsistent resolution for a macro");
                 }
-            } else {
+            } else if this.tcx.dcx().has_errors().is_none() && this.privacy_errors.is_empty() {
                 // It's possible that the macro was unresolved (indeterminate) and silently
                 // expanded into a dummy fragment for recovery during expansion.
                 // Now, post-expansion, the resolution may succeed, but we can't change the
                 // past and need to report an error.
                 // However, non-speculative `resolve_path` can successfully return private items
                 // even if speculative `resolve_path` returned nothing previously, so we skip this
-                // less informative error if the privacy error is reported elsewhere.
-                if this.privacy_errors.is_empty() {
-                    this.dcx().emit_err(CannotDetermineMacroResolution {
-                        span,
-                        kind: kind.descr(),
-                        path: Segment::names_to_string(path),
-                    });
-                }
+                // less informative error if no other error is reported elsewhere.
+
+                let err = this.dcx().create_err(CannotDetermineMacroResolution {
+                    span,
+                    kind: kind.descr(),
+                    path: Segment::names_to_string(path),
+                });
+                err.stash(span, MacroResolutionError);
             }
         };
 

tests/ui/derives/issue-36617.rs

@@ -1,16 +1,16 @@
-#![derive(Copy)] //~ ERROR cannot determine resolution for the attribute macro `derive`
+#![derive(Copy)]
 //~^ ERROR `derive` attribute cannot be used at crate level
 
-#![test]//~ ERROR cannot determine resolution for the attribute macro `test`
+#![test]
 //~^ ERROR `test` attribute cannot be used at crate level
 
-#![test_case]//~ ERROR cannot determine resolution for the attribute macro `test_case`
+#![test_case]
 //~^ ERROR `test_case` attribute cannot be used at crate level
 
-#![bench]//~ ERROR cannot determine resolution for the attribute macro `bench`
+#![bench]
 //~^ ERROR `bench` attribute cannot be used at crate level
 
-#![global_allocator]//~ ERROR cannot determine resolution for the attribute macro `global_allocator`
+#![global_allocator]
 //~^ ERROR `global_allocator` attribute cannot be used at crate level
 
 fn main() {}

tests/ui/derives/issue-36617.stderr

@@ -1,43 +1,3 @@
-error: cannot determine resolution for the attribute macro `derive`
-  --> $DIR/issue-36617.rs:1:4
-   |
-LL | #![derive(Copy)]
-   |    ^^^^^^
-   |
-   = note: import resolution is stuck, try simplifying macro imports
-
-error: cannot determine resolution for the attribute macro `test`
-  --> $DIR/issue-36617.rs:4:4
-   |
-LL | #![test]
-   |    ^^^^
-   |
-   = note: import resolution is stuck, try simplifying macro imports
-
-error: cannot determine resolution for the attribute macro `test_case`
-  --> $DIR/issue-36617.rs:7:4
-   |
-LL | #![test_case]
-   |    ^^^^^^^^^
-   |
-   = note: import resolution is stuck, try simplifying macro imports
-
-error: cannot determine resolution for the attribute macro `bench`
-  --> $DIR/issue-36617.rs:10:4
-   |
-LL | #![bench]
-   |    ^^^^^
-   |
-   = note: import resolution is stuck, try simplifying macro imports
-
-error: cannot determine resolution for the attribute macro `global_allocator`
-  --> $DIR/issue-36617.rs:13:4
-   |
-LL | #![global_allocator]
-   |    ^^^^^^^^^^^^^^^^
-   |
-   = note: import resolution is stuck, try simplifying macro imports
-
 error: `derive` attribute cannot be used at crate level
   --> $DIR/issue-36617.rs:1:1
    |
@@ -113,5 +73,5 @@ LL - #![global_allocator]
 LL + #[global_allocator]
    |
 
-error: aborting due to 10 previous errors
+error: aborting due to 5 previous errors
 

tests/ui/extenv/issue-55897.rs

@@ -4,7 +4,6 @@ mod unresolved_env {
     use env; //~ ERROR unresolved import `env`
 
     include!(concat!(env!("NON_EXISTENT"), "/data.rs"));
-    //~^ ERROR cannot determine resolution for the macro `env`
 }
 
 mod nonexistent_env {

tests/ui/extenv/issue-55897.stderr

@@ -1,5 +1,5 @@
 error: environment variable `NON_EXISTENT` not defined at compile time
-  --> $DIR/issue-55897.rs:11:22
+  --> $DIR/issue-55897.rs:10:22
    |
 LL |     include!(concat!(env!("NON_EXISTENT"), "/data.rs"));
    |                      ^^^^^^^^^^^^^^^^^^^^
@@ -8,7 +8,7 @@ LL |     include!(concat!(env!("NON_EXISTENT"), "/data.rs"));
    = note: this error originates in the macro `env` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: suffixes on string literals are invalid
-  --> $DIR/issue-55897.rs:16:22
+  --> $DIR/issue-55897.rs:15:22
    |
 LL |     include!(concat!("NON_EXISTENT"suffix, "/data.rs"));
    |                      ^^^^^^^^^^^^^^^^^^^^ invalid suffix `suffix`
@@ -33,14 +33,6 @@ help: consider importing this module instead
 LL |     use std::env;
    |         ~~~~~~~~
 
-error: cannot determine resolution for the macro `env`
-  --> $DIR/issue-55897.rs:6:22
-   |
-LL |     include!(concat!(env!("NON_EXISTENT"), "/data.rs"));
-   |                      ^^^
-   |
-   = note: import resolution is stuck, try simplifying macro imports
-
-error: aborting due to 5 previous errors
+error: aborting due to 4 previous errors
 
 For more information about this error, try `rustc --explain E0432`.

tests/ui/feature-gates/issue-43106-gating-of-bench.rs

@@ -5,6 +5,5 @@
 #![feature(custom_inner_attributes)]
 
 #![bench                   = "4100"]
-//~^ ERROR cannot determine resolution for the attribute macro `bench`
-//~^^ ERROR `bench` attribute cannot be used at crate level
+//~^ ERROR `bench` attribute cannot be used at crate level
 fn main() {}

tests/ui/feature-gates/issue-43106-gating-of-bench.stderr

@@ -1,17 +1,9 @@
-error: cannot determine resolution for the attribute macro `bench`
-  --> $DIR/issue-43106-gating-of-bench.rs:7:4
-   |
-LL | #![bench                   = "4100"]
-   |    ^^^^^
-   |
-   = note: import resolution is stuck, try simplifying macro imports
-
 error: `bench` attribute cannot be used at crate level
   --> $DIR/issue-43106-gating-of-bench.rs:7:1
    |
 LL | #![bench                   = "4100"]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-...
+LL |
 LL | fn main() {}
    |    ---- the inner attribute doesn't annotate this function
    |
@@ -21,5 +13,5 @@ LL - #![bench                   = "4100"]
 LL + #[bench                   = "4100"]
    |
 
-error: aborting due to 2 previous errors
+error: aborting due to 1 previous error
 

tests/ui/feature-gates/issue-43106-gating-of-test.rs

@@ -2,6 +2,5 @@
 
 #![allow(soft_unstable)]
 #![test                    = "4200"]
-//~^ ERROR cannot determine resolution for the attribute macro `test`
-//~^^ ERROR `test` attribute cannot be used at crate level
+//~^ ERROR `test` attribute cannot be used at crate level
 fn main() {}