Don't lint snake-case on executable crate name

Co-authored-by: Jieyou Xu <jieyouxu@outlook.com>

Author: GilShoshan94

compiler/rustc_lint/src/nonstandard_style.rs

@@ -10,6 +10,7 @@ use rustc_hir::def::{DefKind, Res};
 use rustc_hir::intravisit::FnKind;
 use rustc_hir::{GenericParamKind, PatKind};
 use rustc_middle::ty;
+use rustc_session::config::CrateType;
 use rustc_span::def_id::LocalDefId;
 use rustc_span::symbol::{sym, Ident};
 use rustc_span::{BytePos, Span};
@@ -366,7 +367,9 @@ impl<'tcx> LateLintPass<'tcx> for NonSnakeCase {
                 })
         };
 
-        if let Some(ident) = &crate_ident {
+        if let Some(ident) = &crate_ident
+            && cx.tcx.crate_types().iter().all(|&crate_type| crate_type != CrateType::Executable)
+        {
             self.check_snake_case(cx, "crate", ident);
         }
     }

tests/ui/lint/lint-non-snake-case-crate-2.stderr

@@ -0,0 +1,6 @@
+//@ check-pass
+#![crate_name = "NonSnakeCase"]
+
+#![deny(non_snake_case)]
+
+fn main() {}

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

@@ -1,5 +1,5 @@
 //@ compile-flags: --crate-name NonSnakeCase
-//@ error-pattern: crate `NonSnakeCase` should have a snake case name
+//@ check-pass
 
 #![deny(non_snake_case)]
 

tests/ui/lint/lint-non-snake-case-crate-2.rs renamed to tests/ui/lint/lint-non-snake-case-crate-bin2.rs

@@ -0,0 +1,7 @@
+//@ check-pass
+#![crate_type = "bin"]
+#![crate_name = "NonSnakeCase"]
+
+#![deny(non_snake_case)]
+
+fn main() {}

tests/ui/lint/lint-non-snake-case-crate-bin3.rs

@@ -0,0 +1,6 @@
+#![crate_type = "cdylib"]
+#![crate_name = "NonSnakeCase"]
+//~^ ERROR crate `NonSnakeCase` should have a snake case name
+#![deny(non_snake_case)]
+
+fn main() {}

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

@@ -0,0 +1,14 @@
+error: crate `NonSnakeCase` should have a snake case name
+  --> $DIR/lint-non-snake-case-crate-cdylib.rs:2:18
+   |
+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:4:9
+   |
+LL | #![deny(non_snake_case)]
+   |         ^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+

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

@@ -0,0 +1,6 @@
+#![crate_type = "dylib"]
+#![crate_name = "NonSnakeCase"]
+//~^ ERROR crate `NonSnakeCase` should have a snake case name
+#![deny(non_snake_case)]
+
+fn main() {}

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

@@ -0,0 +1,14 @@
+error: crate `NonSnakeCase` should have a snake case name
+  --> $DIR/lint-non-snake-case-crate-dylib.rs:2:18
+   |
+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:4:9
+   |
+LL | #![deny(non_snake_case)]
+   |         ^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+

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

@@ -1,3 +1,4 @@
+#![crate_type = "lib"]
 #![crate_name = "NonSnakeCase"]
 //~^ ERROR crate `NonSnakeCase` should have a snake case name
 #![deny(non_snake_case)]