Rollup merge of #127581 - fmease:fix-crate_name-validation, r=bjorn3

Fix crate name validation

Reject macro calls inside attribute `#![crate_name]` like in `#![crate_name = concat!("na", "me")]`.

Prior to #117584, the result of the expansion (here: `"name"`) would actually be properly picked up by the compiler and used as the crate name. However since #117584 / on master, we extract the "value" (i.e., the *literal* string literal) of the `#![crate_name]` much earlier in the pipeline way before macro expansion and **skip**/**ignore** any `#![crate_name]`s "assigned to" a macro call. See also #122001.

T-lang has ruled to reject `#![crate_name = MACRO!(...)]` outright very similar to other built-in attributes whose value we need early like `#![crate_type]`. See accepted FCP: https://github.com/rust-lang/rust/issues/122001#issuecomment-2023203182.

Note that the check as implemented in this PR is even more "aggressive" compared to the one of `#![crate_type]` by running as early as possible in order to reject `#![crate_name = MACRO!(...)]` even in "non-normal" executions of `rustc`, namely on *print requests* (e.g., `--print=crate-name` and `--print=file-names`). If I were to move the validation step a bit further back close to the `#![crate_type]` one, `--print=crate-name` (etc.) would *not* exit fatally with an error in this kind of situation but happily report an incorrect crate name (i.e., the "crate name" as if `#![crate_name]` didn't exist / deduced from other sources like `--crate-name` or the file name) which would match the behavior on master. Again, see also #122001.

I'm mentioning this explicitly because I'm not sure if it was that clear in the FCP'ed issue. I argue that my current approach is the most reasonable one. I know (from reading the code and from past experiments) that various print requests are still quite broken (mostly lack of validation).

To the best of my knowledge, there's no print request whose output references/contains a crate *type*, so there's no "inherent need" to move `#![crate_type]`'s validation to happen earlier.

---

Fixes #122001.

https://github.com/rust-lang/rust/labels/relnotes: Compatibility. Breaking change.

1 files changed, 15 insertions, 0 deletions

diff --git a/compiler/rustc_interface/src/errors.rs b/compiler/rustc_interface/src/errors.rs
index b62950d6709..c3b858d4f2e 100644
--- a/compiler/rustc_interface/src/errors.rs
+++ b/compiler/rustc_interface/src/errors.rs
@@ -5,6 +5,21 @@ use rustc_macros::Diagnostic;
 use rustc_span::{Span, Symbol};
 
 #[derive(Diagnostic)]
+#[diag(interface_crate_name_does_not_match)]
+pub(crate) struct CrateNameDoesNotMatch {
+    #[primary_span]
+    pub(crate) span: Span,
+    pub(crate) crate_name: Symbol,
+    pub(crate) attr_crate_name: Symbol,
+}
+
+#[derive(Diagnostic)]
+#[diag(interface_crate_name_invalid)]
+pub(crate) struct CrateNameInvalid<'a> {
+    pub(crate) crate_name: &'a str,
+}
+
+#[derive(Diagnostic)]
 #[diag(interface_ferris_identifier)]
 pub struct FerrisIdentifier {
     #[primary_span]