From e0c479eea2382930bb550bbb7ddb98a841f8c54b Mon Sep 17 00:00:00 2001
From: yukang <moorekang@gmail.com>
Date: Mon, 24 Jul 2023 13:09:52 +0800
Subject: [PATCH] Add help for crate arg when crate name is invalid

---
 compiler/rustc_session/messages.ftl                 |  1 +
 compiler/rustc_session/src/errors.rs                |  8 ++++++++
 compiler/rustc_session/src/output.rs                | 13 +++++++++++--
 src/tools/tidy/src/ui_tests.rs                      |  4 +++-
 tests/ui/command/need-crate-arg-ignore-tidy.x.rs    |  2 ++
 .../ui/command/need-crate-arg-ignore-tidy.x.stderr  |  6 ++++++
 6 files changed, 31 insertions(+), 3 deletions(-)
 create mode 100644 tests/ui/command/need-crate-arg-ignore-tidy.x.rs
 create mode 100644 tests/ui/command/need-crate-arg-ignore-tidy.x.stderr

diff --git a/compiler/rustc_session/messages.ftl b/compiler/rustc_session/messages.ftl
index ee24c6d902f..d4042a2e61a 100644
--- a/compiler/rustc_session/messages.ftl
+++ b/compiler/rustc_session/messages.ftl
@@ -45,6 +45,7 @@ session_int_literal_too_large = integer literal is too large
     .note = value exceeds limit of `{$limit}`
 
 session_invalid_character_in_create_name = invalid character `{$character}` in crate name: `{$crate_name}`
+session_invalid_character_in_create_name_help = you can either pass `--crate-name` on the command line or add `#![crate_name="…"]` to set the crate name
 
 session_invalid_float_literal_suffix = invalid suffix `{$suffix}` for float literal
     .label = invalid suffix `{$suffix}`
diff --git a/compiler/rustc_session/src/errors.rs b/compiler/rustc_session/src/errors.rs
index dd15ad45145..1ffee01b2f1 100644
--- a/compiler/rustc_session/src/errors.rs
+++ b/compiler/rustc_session/src/errors.rs
@@ -199,6 +199,14 @@ pub struct InvalidCharacterInCrateName {
     pub span: Option<Span>,
     pub character: char,
     pub crate_name: Symbol,
+    #[subdiagnostic]
+    pub crate_name_help: Option<InvalidCrateNameHelp>,
+}
+
+#[derive(Subdiagnostic)]
+pub enum InvalidCrateNameHelp {
+    #[help(session_invalid_character_in_create_name_help)]
+    AddCrateName,
 }
 
 #[derive(Subdiagnostic)]
diff --git a/compiler/rustc_session/src/output.rs b/compiler/rustc_session/src/output.rs
index 2088744bc5b..c0884fb21cd 100644
--- a/compiler/rustc_session/src/output.rs
+++ b/compiler/rustc_session/src/output.rs
@@ -2,7 +2,7 @@
 use crate::config::{CrateType, Input, OutFileName, OutputFilenames, OutputType};
 use crate::errors::{
     CrateNameDoesNotMatch, CrateNameEmpty, CrateNameInvalid, FileIsNotWriteable,
-    InvalidCharacterInCrateName,
+    InvalidCharacterInCrateName, InvalidCrateNameHelp,
 };
 use crate::Session;
 use rustc_ast::{self as ast, attr};
@@ -101,7 +101,16 @@ pub fn validate_crate_name(sess: &Session, s: Symbol, sp: Option<Span>) {
                 continue;
             }
             err_count += 1;
-            sess.emit_err(InvalidCharacterInCrateName { span: sp, character: c, crate_name: s });
+            sess.emit_err(InvalidCharacterInCrateName {
+                span: sp,
+                character: c,
+                crate_name: s,
+                crate_name_help: if sp.is_none() {
+                    Some(InvalidCrateNameHelp::AddCrateName)
+                } else {
+                    None
+                },
+            });
         }
     }
 
diff --git a/src/tools/tidy/src/ui_tests.rs b/src/tools/tidy/src/ui_tests.rs
index c3a63952841..18cee7d3d5c 100644
--- a/src/tools/tidy/src/ui_tests.rs
+++ b/src/tools/tidy/src/ui_tests.rs
@@ -116,7 +116,9 @@ pub fn check(path: &Path, bad: &mut bool) {
                 // must strip all of them.
                 let testname =
                     file_path.file_name().unwrap().to_str().unwrap().split_once('.').unwrap().0;
-                if !file_path.with_file_name(testname).with_extension("rs").exists() {
+                if !file_path.with_file_name(testname).with_extension("rs").exists()
+                    && !testname.contains("ignore-tidy")
+                {
                     tidy_error!(bad, "Stray file with UI testing output: {:?}", file_path);
                 }
 
diff --git a/tests/ui/command/need-crate-arg-ignore-tidy.x.rs b/tests/ui/command/need-crate-arg-ignore-tidy.x.rs
new file mode 100644
index 00000000000..b1ac4a4ae21
--- /dev/null
+++ b/tests/ui/command/need-crate-arg-ignore-tidy.x.rs
@@ -0,0 +1,2 @@
+// issue: 113981
+pub fn main() {}
diff --git a/tests/ui/command/need-crate-arg-ignore-tidy.x.stderr b/tests/ui/command/need-crate-arg-ignore-tidy.x.stderr
new file mode 100644
index 00000000000..305f76694f7
--- /dev/null
+++ b/tests/ui/command/need-crate-arg-ignore-tidy.x.stderr
@@ -0,0 +1,6 @@
+error: invalid character `'.'` in crate name: `need_crate_arg_ignore_tidy.x`
+   |
+   = help: you can either pass `--crate-name` on the command line or add `#![crate_name="…"]` to set the crate name
+
+error: aborting due to previous error
+