Add some extra help to cargo new and invalid package names.

src/cargo/ops/cargo_new.rs

@@ -163,23 +163,42 @@ fn check_name(
     // If --name is already used to override, no point in suggesting it
     // again as a fix.
     let name_help = if show_name_help {
-        "\nIf you need a crate name to not match the directory name, consider using --name flag."
+        "\nIf you need a package name to not match the directory name, consider using --name flag."
     } else {
         ""
     };
-    restricted_names::validate_package_name(name, "crate name", name_help)?;
+    let bin_help = || {
+        let mut help = String::from(name_help);
+        if has_bin {
+            help.push_str(&format!(
+                "\n\
+                If you need a binary with the name \"{name}\", use a valid package \
+                name, and set the binary name to be different from the package. \
+                This can be done by setting the binary filename to `src/bin/{name}.rs` \
+                or change the name in Cargo.toml with:\n\
+                \n    \
+                [bin]\n    \
+                name = \"{name}\"\n    \
+                path = \"src/main.rs\"\n\
+            ",
+                name = name
+            ));
+        }
+        help
+    };
+    restricted_names::validate_package_name(name, "package name", &bin_help())?;
 
     if restricted_names::is_keyword(name) {
         anyhow::bail!(
-            "the name `{}` cannot be used as a crate name, it is a Rust keyword{}",
+            "the name `{}` cannot be used as a package name, it is a Rust keyword{}",
             name,
-            name_help
+            bin_help()
         );
     }
     if restricted_names::is_conflicting_artifact_name(name) {
         if has_bin {
             anyhow::bail!(
-                "the name `{}` cannot be used as a crate name, \
+                "the name `{}` cannot be used as a package name, \
                 it conflicts with cargo's build directory names{}",
                 name,
                 name_help
@@ -195,16 +214,17 @@ fn check_name(
     }
     if name == "test" {
         anyhow::bail!(
-            "the name `test` cannot be used as a crate name, \
+            "the name `test` cannot be used as a package name, \
             it conflicts with Rust's built-in test library{}",
-            name_help
+            bin_help()
         );
     }
     if ["core", "std", "alloc", "proc_macro", "proc-macro"].contains(&name) {
         shell.warn(format!(
             "the name `{}` is part of Rust's standard library\n\
-            It is recommended to use a different name to avoid problems.",
-            name
+            It is recommended to use a different name to avoid problems.{}",
+            name,
+            bin_help()
         ))?;
     }
     if restricted_names::is_windows_reserved(name) {
@@ -781,7 +801,7 @@ mod tests {
 
     if let Err(e) = Workspace::new(&path.join("Cargo.toml"), config) {
         crate::display_warning_with_error(
-            "compiling this new crate may not work due to invalid \
+            "compiling this new package may not work due to invalid \
              workspace configuration",
             &e,
             &mut config.shell(),

src/cargo/util/toml/targets.rs

@@ -289,7 +289,11 @@ fn clean_bins(
         }
 
         if restricted_names::is_conflicting_artifact_name(&name) {
-            anyhow::bail!("the binary target name `{}` is forbidden", name)
+            anyhow::bail!(
+                "the binary target name `{}` is forbidden, \
+                 it conflicts with with cargo's build directory names",
+                name
+            )
         }
     }
 

tests/testsuite/build.rs

@@ -366,7 +366,7 @@ fn cargo_compile_with_forbidden_bin_target_name() {
 [ERROR] failed to parse manifest at `[..]`
 
 Caused by:
-  the binary target name `build` is forbidden
+  the binary target name `build` is forbidden, it conflicts with with cargo's build directory names
 ",
         )
         .run();

tests/testsuite/init.rs

@@ -304,8 +304,17 @@ fn invalid_dir_name() {
         .with_status(101)
         .with_stderr(
             "\
-[ERROR] invalid character `.` in crate name: `foo.bar`, [..]
-If you need a crate name to not match the directory name, consider using --name flag.
+[ERROR] invalid character `.` in package name: `foo.bar`, [..]
+If you need a package name to not match the directory name, consider using --name flag.
+If you need a binary with the name \"foo.bar\", use a valid package name, \
+and set the binary name to be different from the package. \
+This can be done by setting the binary filename to `src/bin/foo.bar.rs` \
+or change the name in Cargo.toml with:
+
+    [bin]
+    name = \"foo.bar\"
+    path = \"src/main.rs\"
+
 ",
         )
         .run();
@@ -323,8 +332,17 @@ fn reserved_name() {
         .with_status(101)
         .with_stderr(
             "\
-[ERROR] the name `test` cannot be used as a crate name, it conflicts [..]\n\
-If you need a crate name to not match the directory name, consider using --name flag.
+[ERROR] the name `test` cannot be used as a package name, it conflicts [..]\n\
+If you need a package name to not match the directory name, consider using --name flag.
+If you need a binary with the name \"test\", use a valid package name, \
+and set the binary name to be different from the package. \
+This can be done by setting the binary filename to `src/bin/test.rs` \
+or change the name in Cargo.toml with:
+
+    [bin]
+    name = \"test\"
+    path = \"src/main.rs\"
+
 ",
         )
         .run();

tests/testsuite/new.rs

@@ -118,8 +118,17 @@ fn invalid_characters() {
         .with_status(101)
         .with_stderr(
             "\
-[ERROR] invalid character `.` in crate name: `foo.rs`, [..]
-If you need a crate name to not match the directory name, consider using --name flag.
+[ERROR] invalid character `.` in package name: `foo.rs`, [..]
+If you need a package name to not match the directory name, consider using --name flag.
+If you need a binary with the name \"foo.rs\", use a valid package name, \
+and set the binary name to be different from the package. \
+This can be done by setting the binary filename to `src/bin/foo.rs.rs` \
+or change the name in Cargo.toml with:
+
+    [bin]
+    name = \"foo.rs\"
+    path = \"src/main.rs\"
+
 ",
         )
         .run();
@@ -131,8 +140,17 @@ fn reserved_name() {
         .with_status(101)
         .with_stderr(
             "\
-[ERROR] the name `test` cannot be used as a crate name, it conflicts [..]
-If you need a crate name to not match the directory name, consider using --name flag.
+[ERROR] the name `test` cannot be used as a package name, it conflicts [..]
+If you need a package name to not match the directory name, consider using --name flag.
+If you need a binary with the name \"test\", use a valid package name, \
+and set the binary name to be different from the package. \
+This can be done by setting the binary filename to `src/bin/test.rs` \
+or change the name in Cargo.toml with:
+
+    [bin]
+    name = \"test\"
+    path = \"src/main.rs\"
+
 ",
         )
         .run();
@@ -144,8 +162,8 @@ fn reserved_binary_name() {
         .with_status(101)
         .with_stderr(
             "\
-[ERROR] the name `incremental` cannot be used as a crate name, it conflicts [..]
-If you need a crate name to not match the directory name, consider using --name flag.
+[ERROR] the name `incremental` cannot be used as a package name, it conflicts [..]
+If you need a package name to not match the directory name, consider using --name flag.
 ",
         )
         .run();
@@ -168,8 +186,17 @@ fn keyword_name() {
         .with_status(101)
         .with_stderr(
             "\
-[ERROR] the name `pub` cannot be used as a crate name, it is a Rust keyword
-If you need a crate name to not match the directory name, consider using --name flag.
+[ERROR] the name `pub` cannot be used as a package name, it is a Rust keyword
+If you need a package name to not match the directory name, consider using --name flag.
+If you need a binary with the name \"pub\", use a valid package name, \
+and set the binary name to be different from the package. \
+This can be done by setting the binary filename to `src/bin/pub.rs` \
+or change the name in Cargo.toml with:
+
+    [bin]
+    name = \"pub\"
+    path = \"src/main.rs\"
+
 ",
         )
         .run();
@@ -183,6 +210,16 @@ fn std_name() {
             "\
 [WARNING] the name `core` is part of Rust's standard library
 It is recommended to use a different name to avoid problems.
+If you need a package name to not match the directory name, consider using --name flag.
+If you need a binary with the name \"core\", use a valid package name, \
+and set the binary name to be different from the package. \
+This can be done by setting the binary filename to `src/bin/core.rs` \
+or change the name in Cargo.toml with:
+
+    [bin]
+    name = \"core\"
+    path = \"src/main.rs\"
+
 [CREATED] binary (application) `core` package
 ",
         )
@@ -528,8 +565,19 @@ fn explicit_invalid_name_not_suggested() {
     cargo_process("new --name 10-invalid a")
         .with_status(101)
         .with_stderr(
-            "[ERROR] the name `10-invalid` cannot be used as a crate name, \
-            the name cannot start with a digit",
+            "\
+[ERROR] the name `10-invalid` cannot be used as a package name, \
+the name cannot start with a digit\n\
+If you need a binary with the name \"10-invalid\", use a valid package name, \
+and set the binary name to be different from the package. \
+This can be done by setting the binary filename to `src/bin/10-invalid.rs` \
+or change the name in Cargo.toml with:
+
+    [bin]
+    name = \"10-invalid\"
+    path = \"src/main.rs\"
+
+",
         )
         .run();
 }
@@ -615,7 +663,7 @@ fn restricted_windows_name() {
             .with_stderr(
                 "\
 [ERROR] cannot use name `nul`, it is a reserved Windows filename
-If you need a crate name to not match the directory name, consider using --name flag.
+If you need a package name to not match the directory name, consider using --name flag.
 ",
             )
             .run();
@@ -655,9 +703,18 @@ fn non_ascii_name_invalid() {
         .with_status(101)
         .with_stderr(
             "\
-[ERROR] invalid character `Ⓐ` in crate name: `ⒶⒷⒸ`, \
+[ERROR] invalid character `Ⓐ` in package name: `ⒶⒷⒸ`, \
 the first character must be a Unicode XID start character (most letters or `_`)
-If you need a crate name to not match the directory name, consider using --name flag.
+If you need a package name to not match the directory name, consider using --name flag.
+If you need a binary with the name \"ⒶⒷⒸ\", use a valid package name, \
+and set the binary name to be different from the package. \
+This can be done by setting the binary filename to `src/bin/ⒶⒷⒸ.rs` \
+or change the name in Cargo.toml with:
+
+    [bin]
+    name = \"ⒶⒷⒸ\"
+    path = \"src/main.rs\"
+
 ",
         )
         .run();
@@ -667,9 +724,18 @@ If you need a crate name to not match the directory name, consider using --name
         .with_status(101)
         .with_stderr(
             "\
-[ERROR] invalid character `¼` in crate name: `a¼`, \
+[ERROR] invalid character `¼` in package name: `a¼`, \
 characters must be Unicode XID characters (numbers, `-`, `_`, or most letters)
-If you need a crate name to not match the directory name, consider using --name flag.
+If you need a package name to not match the directory name, consider using --name flag.
+If you need a binary with the name \"a¼\", use a valid package name, \
+and set the binary name to be different from the package. \
+This can be done by setting the binary filename to `src/bin/a¼.rs` \
+or change the name in Cargo.toml with:
+
+    [bin]
+    name = \"a¼\"
+    path = \"src/main.rs\"
+
 ",
         )
         .run();

tests/testsuite/workspaces.rs

@@ -1034,7 +1034,7 @@ fn new_warns_you_this_will_not_work() {
         .env("USER", "foo")
         .with_stderr(
             "\
-warning: compiling this new crate may not work due to invalid workspace configuration
+warning: compiling this new package may not work due to invalid workspace configuration
 
 current package believes it's in a workspace when it's not:
 current: [..]
@@ -1056,7 +1056,7 @@ fn new_warning_with_corrupt_ws() {
         .env("USER", "foo")
         .with_stderr(
             "\
-[WARNING] compiling this new crate may not work due to invalid workspace configuration
+[WARNING] compiling this new package may not work due to invalid workspace configuration
 
 failed to parse manifest at `[..]foo/Cargo.toml`