Supress unhelpful diagnostics for unresolved top level attributes

Author: chenyukang

compiler/rustc_passes/src/check_attr.rs

@@ -2495,12 +2495,8 @@ fn is_c_like_enum(item: &Item<'_>) -> bool {
     }
 }
 
-// FIXME: Fix "Cannot determine resolution" error and remove built-in macros
-// from this check.
+// builtin macros will be checked in resolve
 fn check_invalid_crate_level_attr(tcx: TyCtxt<'_>, attrs: &[Attribute]) {
-    // Check for builtin attributes at the crate level
-    // which were unsuccessfully resolved due to cannot determine
-    // resolution for the attribute macro error.
     const ATTRS_TO_CHECK: &[Symbol] = &[
         sym::macro_export,
         sym::repr,
@@ -2509,11 +2505,6 @@ fn check_invalid_crate_level_attr(tcx: TyCtxt<'_>, attrs: &[Attribute]) {
         sym::start,
         sym::rustc_main,
         sym::unix_sigpipe,
-        sym::derive,
-        sym::test,
-        sym::test_case,
-        sym::global_allocator,
-        sym::bench,
     ];
 
     for attr in attrs {

compiler/rustc_resolve/messages.ftl

@@ -151,6 +151,10 @@ resolve_invalid_asm_sym =
     .label = is a local variable
     .help = `sym` operands must refer to either a function or a static
 
+resolve_invalid_attr_at_crate_level =
+    `{$name}` attribute cannot be used at crate level
+    .suggestion = perhaps you meant to use an outer attribute
+
 resolve_is_not_directly_importable =
     `{$target}` is not directly importable
     .label = cannot be imported directly

compiler/rustc_resolve/src/errors.rs

@@ -771,3 +771,26 @@ pub(crate) struct IsNotDirectlyImportable {
     pub(crate) span: Span,
     pub(crate) target: Ident,
 }
+
+#[derive(Diagnostic)]
+#[diag(resolve_invalid_attr_at_crate_level)]
+pub struct InvalidAttrAtCrateLevel {
+    #[primary_span]
+    pub(crate) span: Span,
+    pub(crate) name: Symbol,
+    #[subdiagnostic]
+    pub(crate) sugg: InvalidAttrSugg,
+}
+
+#[derive(Subdiagnostic)]
+#[suggestion(
+    resolve_suggestion,
+    code = "",
+    applicability = "machine-applicable",
+    style = "verbose"
+)]
+pub(crate) struct InvalidAttrSugg {
+    #[primary_span]
+    pub(crate) span: Span,
+    pub(crate) name: Symbol,
+}

compiler/rustc_resolve/src/lib.rs

@@ -1584,6 +1584,13 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
         self.get_macro(res).is_some_and(|macro_data| macro_data.ext.builtin_name.is_some())
     }
 
+    fn is_builtin(&mut self, res: Res) -> bool {
+        if self.is_builtin_macro(res) {
+            return true;
+        }
+        self.builtin_attrs_bindings.values().any(|b| b.res() == res)
+    }
+
     fn macro_def(&self, mut ctxt: SyntaxContext) -> DefId {
         loop {
             match ctxt.outer_expn_data().macro_def_id {

compiler/rustc_resolve/src/macros.rs

@@ -1,6 +1,8 @@
 //! A bunch of methods and structures more or less related to resolving macros and
 //! interface provided by `Resolver` to macro expander.
 
+use crate::ast::AttrStyle;
+use crate::ast::Attribute;
 use crate::errors::{
     self, AddAsNonDerive, CannotDetermineMacroResolution, CannotFindIdentInThisScope,
     MacroExpectedFound, RemoveSurroundingDerive,
@@ -35,6 +37,7 @@ use rustc_span::edition::Edition;
 use rustc_span::hygiene::{self, ExpnData, ExpnKind, LocalExpnId};
 use rustc_span::hygiene::{AstPass, MacroKind};
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
+use rustc_span::BytePos;
 use rustc_span::{Span, DUMMY_SP};
 use std::cell::Cell;
 use std::mem;
@@ -698,6 +701,35 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
         res.map(|res| (self.get_macro(res).map(|macro_data| macro_data.ext.clone()), res))
     }
 
+    fn report_invalid_crate_level_attr(&mut self, attrs: &[Attribute], name: Symbol) -> bool {
+        for attr in attrs.iter().filter(|attr| attr.style == AttrStyle::Inner) {
+            if attr.has_name(name) {
+                let tcx = self.tcx;
+                tcx.sess.emit_err(errors::InvalidAttrAtCrateLevel {
+                    name,
+                    span: attr.span,
+                    sugg: errors::InvalidAttrSugg {
+                        span: tcx
+                            .sess
+                            .source_map()
+                            .span_to_snippet(attr.span)
+                            .ok()
+                            .filter(|src| src.starts_with("#!["))
+                            .map(|_| {
+                                attr.span
+                                    .with_lo(attr.span.lo() + BytePos(1))
+                                    .with_hi(attr.span.lo() + BytePos(2))
+                            })
+                            .unwrap(),
+                        name,
+                    },
+                });
+                return true;
+            }
+        }
+        false
+    }
+
     pub(crate) fn finalize_macro_resolutions(&mut self, krate: &Crate) {
         let check_consistency = |this: &mut Self,
                                  path: &[Segment],
@@ -717,15 +749,28 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                 // 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
+                // Special cases:
+                // 1. 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.
+                // 2. issue #118455, unresolved top level attribute error didn't imported prelude and
+                // already have emitted an error, report builtin macro and attributes error by the way,
+                // so `check_invalid_crate_level_attr` in can ignore them.
+
+                let is_builtin = res.opt_def_id().map_or(false, |_| this.is_builtin(res));
                 if this.privacy_errors.is_empty() {
-                    this.tcx.sess.emit_err(CannotDetermineMacroResolution {
-                        span,
-                        kind: kind.descr(),
-                        path: Segment::names_to_string(path),
-                    });
+                    let mut fallback = !is_builtin;
+                    if is_builtin && krate.id == ast::CRATE_NODE_ID {
+                        fallback =
+                            !this.report_invalid_crate_level_attr(&krate.attrs, path[0].ident.name);
+                    }
+                    if fallback && this.tcx.sess.has_errors().is_none() {
+                        this.tcx.sess.emit_err(CannotDetermineMacroResolution {
+                            span,
+                            kind: kind.descr(),
+                            path: Segment::names_to_string(path),
+                        });
+                    }
                 }
             }
         };

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

@@ -1,51 +1,8 @@
-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
    |
 LL | #![derive(Copy)]
    | ^^^^^^^^^^^^^^^^
-...
-LL | fn main() {}
-   |    ---- the inner attribute doesn't annotate this function
    |
 help: perhaps you meant to use an outer attribute
    |
@@ -58,9 +15,6 @@ error: `test` attribute cannot be used at crate level
    |
 LL | #![test]
    | ^^^^^^^^
-...
-LL | fn main() {}
-   |    ---- the inner attribute doesn't annotate this function
    |
 help: perhaps you meant to use an outer attribute
    |
@@ -73,9 +27,6 @@ error: `test_case` attribute cannot be used at crate level
    |
 LL | #![test_case]
    | ^^^^^^^^^^^^^
-...
-LL | fn main() {}
-   |    ---- the inner attribute doesn't annotate this function
    |
 help: perhaps you meant to use an outer attribute
    |
@@ -88,9 +39,6 @@ error: `bench` attribute cannot be used at crate level
    |
 LL | #![bench]
    | ^^^^^^^^^
-...
-LL | fn main() {}
-   |    ---- the inner attribute doesn't annotate this function
    |
 help: perhaps you meant to use an outer attribute
    |
@@ -103,15 +51,12 @@ error: `global_allocator` attribute cannot be used at crate level
    |
 LL | #![global_allocator]
    | ^^^^^^^^^^^^^^^^^^^^
-...
-LL | fn main() {}
-   |    ---- the inner attribute doesn't annotate this function
    |
 help: perhaps you meant to use an outer attribute
    |
 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

@@ -3,8 +3,6 @@
 // handled in "weird places" when `--test` is passed.
 
 #![feature(custom_inner_attributes)]
-
-#![bench                   = "4100"]
-//~^ ERROR cannot determine resolution for the attribute macro `bench`
-//~^^ ERROR `bench` attribute cannot be used at crate level
+#![bench = "4100"]
+//~^ ERROR `bench` attribute cannot be used at crate level
 fn main() {}

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

@@ -1,25 +1,14 @@
-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
+  --> $DIR/issue-43106-gating-of-bench.rs:6:1
    |
-LL | #![bench                   = "4100"]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-...
-LL | fn main() {}
-   |    ---- the inner attribute doesn't annotate this function
+LL | #![bench = "4100"]
+   | ^^^^^^^^^^^^^^^^^^
    |
 help: perhaps you meant to use an outer attribute
    |
-LL - #![bench                   = "4100"]
-LL + #[bench                   = "4100"]
+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

@@ -1,7 +1,6 @@
 // The non-crate level cases are in issue-43106-gating-of-builtin-attrs.rs.
 
 #![allow(soft_unstable)]
-#![test                    = "4200"]
-//~^ ERROR cannot determine resolution for the attribute macro `test`
-//~^^ ERROR `test` attribute cannot be used at crate level
+#![test = "4200"]
+//~^ ERROR `test` attribute cannot be used at crate level
 fn main() {}