Explain why non_snake_case is skipped for binary crates and cleanup tests

compiler/rustc_lint/src/nonstandard_style.rs

@@ -332,6 +332,9 @@ impl<'tcx> LateLintPass<'tcx> for NonSnakeCase {
             return;
         }
 
+        // Issue #45127: don't enforce `snake_case` for binary crates as binaries are not intended
+        // to be distributed and depended on like libraries. The lint is not suppressed for cdylib
+        // or staticlib because it's not clear what the desired lint behavior for those are.
         if cx.tcx.crate_types().iter().all(|&crate_type| crate_type == CrateType::Executable) {
             return;
         }

tests/ui/lint/non-snake-case/lint-non-snake-case-crate-lib.stderr → tests/ui/lint/non-snake-case/lint-non-snake-case-crate.cdylib_.stderr

@@ -1,11 +1,11 @@
 error: crate `NonSnakeCase` should have a snake case name
-  --> $DIR/lint-non-snake-case-crate-lib.rs:3:18
+  --> $DIR/lint-non-snake-case-crate.rs:25:18
    |
 LL | #![crate_name = "NonSnakeCase"]
    |                  ^^^^^^^^^^^^ help: convert the identifier to snake case: `non_snake_case`
    |
 note: the lint level is defined here
-  --> $DIR/lint-non-snake-case-crate-lib.rs:5:9
+  --> $DIR/lint-non-snake-case-crate.rs:27:9
    |
 LL | #![deny(non_snake_case)]
    |         ^^^^^^^^^^^^^^

tests/ui/lint/non-snake-case/lint-non-snake-case-crate-rlib.stderr → tests/ui/lint/non-snake-case/lint-non-snake-case-crate.dylib_.stderr

@@ -1,11 +1,11 @@
 error: crate `NonSnakeCase` should have a snake case name
-  --> $DIR/lint-non-snake-case-crate-rlib.rs:3:18
+  --> $DIR/lint-non-snake-case-crate.rs:25:18
    |
 LL | #![crate_name = "NonSnakeCase"]
    |                  ^^^^^^^^^^^^ help: convert the identifier to snake case: `non_snake_case`
    |
 note: the lint level is defined here
-  --> $DIR/lint-non-snake-case-crate-rlib.rs:5:9
+  --> $DIR/lint-non-snake-case-crate.rs:27:9
    |
 LL | #![deny(non_snake_case)]
    |         ^^^^^^^^^^^^^^

tests/ui/lint/non-snake-case/lint-non-snake-case-crate-dylib.stderr → tests/ui/lint/non-snake-case/lint-non-snake-case-crate.lib_.stderr

@@ -1,11 +1,11 @@
 error: crate `NonSnakeCase` should have a snake case name
-  --> $DIR/lint-non-snake-case-crate-dylib.rs:3:18
+  --> $DIR/lint-non-snake-case-crate.rs:25:18
    |
 LL | #![crate_name = "NonSnakeCase"]
    |                  ^^^^^^^^^^^^ help: convert the identifier to snake case: `non_snake_case`
    |
 note: the lint level is defined here
-  --> $DIR/lint-non-snake-case-crate-dylib.rs:5:9
+  --> $DIR/lint-non-snake-case-crate.rs:27:9
    |
 LL | #![deny(non_snake_case)]
    |         ^^^^^^^^^^^^^^

tests/ui/lint/non-snake-case/lint-non-snake-case-crate-cdylib.stderr → tests/ui/lint/non-snake-case/lint-non-snake-case-crate.proc_macro_.stderr

@@ -1,11 +1,11 @@
 error: crate `NonSnakeCase` should have a snake case name
-  --> $DIR/lint-non-snake-case-crate-cdylib.rs:3:18
+  --> $DIR/lint-non-snake-case-crate.rs:25:18
    |
 LL | #![crate_name = "NonSnakeCase"]
    |                  ^^^^^^^^^^^^ help: convert the identifier to snake case: `non_snake_case`
    |
 note: the lint level is defined here
-  --> $DIR/lint-non-snake-case-crate-cdylib.rs:5:9
+  --> $DIR/lint-non-snake-case-crate.rs:27:9
    |
 LL | #![deny(non_snake_case)]
    |         ^^^^^^^^^^^^^^

tests/ui/lint/non-snake-case/lint-non-snake-case-crate.rlib_.stderr

@@ -0,0 +1,14 @@
+error: crate `NonSnakeCase` should have a snake case name
+  --> $DIR/lint-non-snake-case-crate.rs:25:18
+   |
+LL | #![crate_name = "NonSnakeCase"]
+   |                  ^^^^^^^^^^^^ help: convert the identifier to snake case: `non_snake_case`
+   |
+note: the lint level is defined here
+  --> $DIR/lint-non-snake-case-crate.rs:27:9
+   |
+LL | #![deny(non_snake_case)]
+   |         ^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+

tests/ui/lint/non-snake-case/lint-non-snake-case-crate.rs

@@ -0,0 +1,29 @@
+//! Don't lint on binary crate with non-snake-case names.
+//!
+//! See <https://github.com/rust-lang/rust/issues/45127>.
+
+//@ revisions: bin_ cdylib_ dylib_ lib_ proc_macro_ rlib_ staticlib_
+
+// Should not fire on binary crates.
+//@[bin_] compile-flags: --crate-type=bin
+//@[bin_] check-pass
+
+// But should fire on non-binary crates.
+
+//@[cdylib_] ignore-musl (dylibs are not supported)
+//@[dylib_] ignore-musl (dylibs are not supported)
+//@[dylib_] ignore-wasm (dylib is not supported)
+//@[proc_macro_] ignore-wasm (dylib is not supported)
+
+//@[cdylib_] compile-flags: --crate-type=cdylib
+//@[dylib_] compile-flags: --crate-type=dylib
+//@[lib_] compile-flags: --crate-type=lib
+//@[proc_macro_] compile-flags: --crate-type=proc-macro
+//@[rlib_] compile-flags: --crate-type=rlib
+//@[staticlib_] compile-flags: --crate-type=staticlib
+
+#![crate_name = "NonSnakeCase"]
+//[cdylib_,dylib_,lib_,proc_macro_,rlib_,staticlib_]~^ ERROR crate `NonSnakeCase` should have a snake case name
+#![deny(non_snake_case)]
+
+fn main() {}

tests/ui/lint/non-snake-case/lint-non-snake-case-crate.staticlib_.stderr

@@ -0,0 +1,14 @@
+error: crate `NonSnakeCase` should have a snake case name
+  --> $DIR/lint-non-snake-case-crate.rs:25:18
+   |
+LL | #![crate_name = "NonSnakeCase"]
+   |                  ^^^^^^^^^^^^ help: convert the identifier to snake case: `non_snake_case`
+   |
+note: the lint level is defined here
+  --> $DIR/lint-non-snake-case-crate.rs:27:9
+   |
+LL | #![deny(non_snake_case)]
+   |         ^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+