Improve -Z crate-attr diagnostics

- Move `crate-attr` parsing from `rustc_builtin_macros` to
  `rustc_parse`.  This is not a built-in macro.
- Show the `#![ ... ]` in the span (to make it clear that it should not
  be included in the CLI argument)
- Show more detailed errors when the crate has valid token trees but
  invalid syntax.
  Previously, `crate-attr=feature(foo),feature(bar)` would just say
  "invalid crate attribute" and point at the comma. Now, it explicitly
  says that the comma was unexpected, which is useful when using
  `--error-format=short`. It also fixes the column to show the correct
  span.
- Recover from parse errors. Previously we would abort immediately on
  syntax errors; now we go on to try and type-check the rest of the
  crate.

The new diagnostic code also happens to be slightly shorter.

Author: jyn514

compiler/rustc_ast/src/attr/mod.rs

@@ -619,7 +619,7 @@ pub fn mk_doc_comment(
     Attribute { kind: AttrKind::DocComment(comment_kind, data), id: g.mk_attr_id(), style, span }
 }
 
-pub fn mk_attr(
+fn mk_attr(
     g: &AttrIdGenerator,
     style: AttrStyle,
     unsafety: Safety,

compiler/rustc_builtin_macros/src/cmdline_attrs.rs

@@ -109,13 +109,6 @@ pub(crate) struct ProcMacro {
     pub(crate) span: Span,
 }
 
-#[derive(Diagnostic)]
-#[diag(builtin_macros_invalid_crate_attribute)]
-pub(crate) struct InvalidCrateAttr {
-    #[primary_span]
-    pub(crate) span: Span,
-}
-
 #[derive(Diagnostic)]
 #[diag(builtin_macros_non_abi)]
 pub(crate) struct NonABI {

compiler/rustc_builtin_macros/src/errors.rs

@@ -53,7 +53,6 @@ mod test;
 mod trace_macros;
 
 pub mod asm;
-pub mod cmdline_attrs;
 pub mod contracts;
 pub mod proc_macro_harness;
 pub mod standard_library_imports;

compiler/rustc_builtin_macros/src/lib.rs

@@ -757,7 +757,7 @@ pub fn create_and_enter_global_ctxt<T, F: for<'tcx> FnOnce(TyCtxt<'tcx>) -> T>(
 ) -> T {
     let sess = &compiler.sess;
 
-    rustc_builtin_macros::cmdline_attrs::inject(
+    rustc_parse::cmdline_attrs::inject(
         &mut krate,
         &sess.psess,
         &sess.opts.unstable_opts.crate_attr,

compiler/rustc_interface/src/passes.rs

@@ -32,6 +32,7 @@ pub const MACRO_ARGUMENTS: Option<&str> = Some("macro arguments");
 
 #[macro_use]
 pub mod parser;
+pub use parser::cmdline_attrs;
 use parser::{Parser, make_unclosed_delims_error};
 pub mod lexer;
 pub mod validate_attr;

compiler/rustc_parse/src/lib.rs

@@ -0,0 +1,31 @@
+//! Attributes injected into the crate root from command line using `-Z crate-attr`.
+
+use rustc_ast::{self as ast};
+use rustc_errors::Diag;
+use rustc_session::parse::ParseSess;
+use rustc_span::FileName;
+
+use crate::{parse_in, source_str_to_stream};
+
+use super::attr::InnerAttrPolicy;
+
+pub fn inject(krate: &mut ast::Crate, psess: &ParseSess, attrs: &[String]) {
+    for raw_attr in attrs {
+        let source = format!("#![{raw_attr}]");
+        let parse = || -> Result<ast::Attribute, Vec<Diag<'_>>> {
+            let tokens = source_str_to_stream(psess, FileName::cli_crate_attr_source_code(raw_attr), source, None)?;
+            parse_in(psess, tokens, "<crate attribute>", |p| p.parse_attribute(InnerAttrPolicy::Permitted)).map_err(|e| vec![e])
+        };
+        let meta = match parse() {
+            Ok(meta) => meta,
+            Err(errs) => {
+                for err in errs {
+                    err.emit();
+                }
+                continue;
+            }
+        };
+
+        krate.attrs.push(meta);
+    }
+}

compiler/rustc_parse/src/parser/cmdline_attrs.rs

@@ -1,5 +1,6 @@
 pub mod attr;
 mod attr_wrapper;
+pub mod cmdline_attrs;
 mod diagnostics;
 mod expr;
 mod generics;

compiler/rustc_parse/src/parser/mod.rs

@@ -1,20 +1,20 @@
 error: unknown start of token: `
-  --> <crate attribute>:1:1
+  --> <crate attribute>:1:4
    |
-LL | `%~@$#
-   | ^
+LL | #![`%~@$#]
+   |    ^
    |
 help: Unicode character '`' (Grave Accent) looks like ''' (Single Quote), but it is not
    |
-LL - `%~@$#
-LL + '%~@$#
+LL - #![`%~@$#]
+LL + #!['%~@$#]
    |
 
 error: expected identifier, found `%`
-  --> <crate attribute>:1:2
+  --> <crate attribute>:1:5
    |
-LL | `%~@$#
-   |  ^ expected identifier
+LL | #![`%~@$#]
+   |     ^ expected identifier
 
 error: aborting due to 2 previous errors
 

tests/ui/attributes/z-crate-attr/garbage.stderr

@@ -1,8 +1,15 @@
-error: unexpected closing delimiter: `]`
-  --> <crate attribute>:1:19
+error: unexpected token: keyword `fn`
+  --> <crate attribute>:1:23
    |
-LL | feature(yeet_expr)]fn main(){}#[inline
-   |                   ^ unexpected closing delimiter
+LL | #![feature(yeet_expr)]fn main(){}#[inline]
+   |                       ^^ unexpected token after this
 
-error: aborting due to 1 previous error
+error[E0601]: `main` function not found in crate `injection`
+  --> $DIR/injection.rs:3:12
+   |
+LL | fn foo() {}
+   |            ^ consider adding a `main` function to `$DIR/injection.rs`
+
+error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0601`.

tests/ui/attributes/z-crate-attr/injection.stderr

@@ -1,8 +1,8 @@
 error: expected identifier, found `#`
-  --> <crate attribute>:1:1
+  --> <crate attribute>:1:4
    |
-LL | #![feature(foo)]
-   | ^ expected identifier
+LL | #![#![feature(foo)]]
+   |    ^ expected identifier
 
 error: aborting due to 1 previous error
 

tests/ui/attributes/z-crate-attr/inner-attr.stderr

@@ -1,8 +1,8 @@
-error: invalid crate attribute
-  --> <crate attribute>:1:1
+error: expected `]`, found `,`
+  --> <crate attribute>:1:16
    |
-LL | feature(foo),feature(bar)
-   | ^^^^^^^^^^^^^
+LL | #![feature(foo),feature(bar)]
+   |                ^ expected `]`
 
 error: aborting due to 1 previous error
 

tests/ui/attributes/z-crate-attr/multiple.stderr

@@ -1,10 +1,11 @@
-error: this file contains an unclosed delimiter
-  --> <crate attribute>:1:2
+error: mismatched closing delimiter: `]`
+  --> <crate attribute>:1:4
    |
-LL | (
-   | -^
-   | |
-   | unclosed delimiter
+LL | #![(]
+   |   -^^ mismatched closing delimiter
+   |   ||
+   |   |unclosed delimiter
+   |   closing delimiter possibly meant for this
 
 error: aborting due to 1 previous error