From f262297e9aed013ca61a891951f639b85788ef14 Mon Sep 17 00:00:00 2001
From: hi-rustin <rustin.liu@gmail.com>
Date: Tue, 19 Sep 2023 10:46:05 +0800
Subject: [PATCH 1/5] Add test for using unsupported mode in build command

---
 tests/testsuite/build.rs | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/tests/testsuite/build.rs b/tests/testsuite/build.rs
index 3c650ca5213..b5ad0836958 100644
--- a/tests/testsuite/build.rs
+++ b/tests/testsuite/build.rs
@@ -135,6 +135,27 @@ fn incremental_config() {
         .run();
 }
 
+#[cargo_test]
+fn cargo_compile_with_unsupported_mode() {
+    let p = project()
+        .file("Cargo.toml", &basic_bin_manifest("foo"))
+        .file("src/foo.rs", &main_file(r#""i am foo""#, &[]))
+        .build();
+
+    p.cargo("build --debug")
+        .with_stderr(
+            "\
+error: unexpected argument '--debug' found
+
+Usage: cargo[EXE] build [OPTIONS]
+
+For more information, try '--help'.
+",
+        )
+        .with_status(1)
+        .run();
+}
+
 #[cargo_test]
 fn cargo_compile_with_workspace_excluded() {
     let p = project().file("src/main.rs", "fn main() {}").build();

From ed86337492b41713333490df7d8f12e79dad9960 Mon Sep 17 00:00:00 2001
From: hi-rustin <rustin.liu@gmail.com>
Date: Tue, 19 Sep 2023 10:35:12 +0800
Subject: [PATCH 2/5] Better suggestion for unsupported mode in build command

---
 src/bin/cargo/commands/build.rs   |  1 +
 src/cargo/util/command_prelude.rs | 21 +++++++++++++++++++--
 tests/testsuite/build.rs          |  2 ++
 3 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/src/bin/cargo/commands/build.rs b/src/bin/cargo/commands/build.rs
index 7197cdbad35..8d94f3d1db0 100644
--- a/src/bin/cargo/commands/build.rs
+++ b/src/bin/cargo/commands/build.rs
@@ -30,6 +30,7 @@ pub fn cli() -> Command {
         )
         .arg_features()
         .arg_release("Build artifacts in release mode, with optimizations")
+        .arg_unsupported_mode("debug", "build", "release")
         .arg_profile("Build artifacts with the specified profile")
         .arg_parallel()
         .arg_target_triple("Build for the target triple")
diff --git a/src/cargo/util/command_prelude.rs b/src/cargo/util/command_prelude.rs
index c8dc4df87c1..303f965a74e 100644
--- a/src/cargo/util/command_prelude.rs
+++ b/src/cargo/util/command_prelude.rs
@@ -112,6 +112,19 @@ pub trait CommandExt: Sized {
         self._arg(flag("keep-going", "").value_parser(value_parser).hide(true))
     }
 
+    fn arg_unsupported_mode(
+        self,
+        want: &'static str,
+        command: &'static str,
+        actual: &'static str,
+    ) -> Self {
+        let msg = format!(
+            "There is no `--{want}` for `cargo {command}`. Only `--{actual}` is supported."
+        );
+        let value_parser = UnknownArgumentValueParser::suggest(msg);
+        self._arg(flag(want, "").value_parser(value_parser).hide(true))
+    }
+
     fn arg_targets_all(
         self,
         lib: &'static str,
@@ -486,7 +499,7 @@ Run `{cmd}` to see possible targets."
             (Some(name @ ("dev" | "test" | "bench" | "check")), ProfileChecking::LegacyRustc)
             // `cargo fix` and `cargo check` has legacy handling of this profile name
             | (Some(name @ "test"), ProfileChecking::LegacyTestOnly) => {
-                if self.flag("release") {
+                if self.maybe_flag("release") {
                     config.shell().warn(
                         "the `--release` flag should not be specified with the `--profile` flag\n\
                          The `--release` flag will be ignored.\n\
@@ -510,7 +523,11 @@ Run `{cmd}` to see possible targets."
             )
         };
 
-        let name = match (self.flag("release"), self.flag("debug"), specified_profile) {
+        let name = match (
+            self.maybe_flag("release"),
+            self.flag("debug"),
+            specified_profile,
+        ) {
             (false, false, None) => default,
             (true, _, None | Some("release")) => "release",
             (true, _, Some(name)) => return Err(conflict("release", "release", name)),
diff --git a/tests/testsuite/build.rs b/tests/testsuite/build.rs
index b5ad0836958..cb8c274939f 100644
--- a/tests/testsuite/build.rs
+++ b/tests/testsuite/build.rs
@@ -147,6 +147,8 @@ fn cargo_compile_with_unsupported_mode() {
             "\
 error: unexpected argument '--debug' found
 
+  tip: There is no `--debug` for `cargo build`. Only `--release` is supported.
+
 Usage: cargo[EXE] build [OPTIONS]
 
 For more information, try '--help'.

From 7644a4bd969d5b3913c87d3dcbe0eca0bbda57f2 Mon Sep 17 00:00:00 2001
From: hi-rustin <rustin.liu@gmail.com>
Date: Tue, 19 Sep 2023 10:52:27 +0800
Subject: [PATCH 3/5] Add test for using unsupported mode in install command

---
 tests/testsuite/install.rs | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/tests/testsuite/install.rs b/tests/testsuite/install.rs
index c7658037271..ccd9be49bf0 100644
--- a/tests/testsuite/install.rs
+++ b/tests/testsuite/install.rs
@@ -2443,3 +2443,23 @@ fn ambiguous_registry_vs_local_package() {
         .run();
     assert_has_installed_exe(cargo_home(), "foo");
 }
+
+#[cargo_test]
+fn install_with_unsupported_mode() {
+    pkg("foo", "0.0.1");
+
+    cargo_process("install foo --release")
+        .with_stderr(
+            "\
+error: unexpected argument '--release' found
+
+  tip: a similar argument exists: '--examples'
+
+Usage: cargo[EXE] install --examples [crate]...
+
+For more information, try '--help'.
+",
+        )
+        .with_status(1)
+        .run();
+}

From 817c2cbbb5b266440efcf4a1aa1a750d79694be9 Mon Sep 17 00:00:00 2001
From: hi-rustin <rustin.liu@gmail.com>
Date: Tue, 19 Sep 2023 10:47:09 +0800
Subject: [PATCH 4/5] Better suggestion for unsupported mode in install command

---
 src/bin/cargo/commands/install.rs | 1 +
 src/cargo/util/command_prelude.rs | 2 +-
 tests/testsuite/install.rs        | 4 ++--
 3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/bin/cargo/commands/install.rs b/src/bin/cargo/commands/install.rs
index 010a4f48385..57063f11dc8 100644
--- a/src/bin/cargo/commands/install.rs
+++ b/src/bin/cargo/commands/install.rs
@@ -83,6 +83,7 @@ pub fn cli() -> Command {
             "debug",
             "Build in debug mode (with the 'dev' profile) instead of release mode",
         ))
+        .arg_unsupported_mode("release", "install", "debug")
         .arg_profile("Install artifacts with the specified profile")
         .arg_target_triple("Build for the target triple")
         .arg_target_dir()
diff --git a/src/cargo/util/command_prelude.rs b/src/cargo/util/command_prelude.rs
index 303f965a74e..270b558c6c2 100644
--- a/src/cargo/util/command_prelude.rs
+++ b/src/cargo/util/command_prelude.rs
@@ -525,7 +525,7 @@ Run `{cmd}` to see possible targets."
 
         let name = match (
             self.maybe_flag("release"),
-            self.flag("debug"),
+            self.maybe_flag("debug"),
             specified_profile,
         ) {
             (false, false, None) => default,
diff --git a/tests/testsuite/install.rs b/tests/testsuite/install.rs
index ccd9be49bf0..b49cbec315e 100644
--- a/tests/testsuite/install.rs
+++ b/tests/testsuite/install.rs
@@ -2453,9 +2453,9 @@ fn install_with_unsupported_mode() {
             "\
 error: unexpected argument '--release' found
 
-  tip: a similar argument exists: '--examples'
+  tip: There is no `--release` for `cargo install`. Only `--debug` is supported.
 
-Usage: cargo[EXE] install --examples [crate]...
+Usage: cargo[EXE] install [OPTIONS] [crate]...
 
 For more information, try '--help'.
 ",

From 97656fbf8787551f002119b971c333cbfdb888ca Mon Sep 17 00:00:00 2001
From: hi-rustin <rustin.liu@gmail.com>
Date: Wed, 20 Sep 2023 19:32:35 +0800
Subject: [PATCH 5/5] Correct the helper name and the tip message

---
 src/bin/cargo/commands/build.rs   |  2 +-
 src/bin/cargo/commands/install.rs |  2 +-
 src/cargo/util/command_prelude.rs | 12 +++++-------
 tests/testsuite/build.rs          |  4 ++--
 tests/testsuite/install.rs        |  4 ++--
 5 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/src/bin/cargo/commands/build.rs b/src/bin/cargo/commands/build.rs
index 8d94f3d1db0..d503f43ddcc 100644
--- a/src/bin/cargo/commands/build.rs
+++ b/src/bin/cargo/commands/build.rs
@@ -30,7 +30,7 @@ pub fn cli() -> Command {
         )
         .arg_features()
         .arg_release("Build artifacts in release mode, with optimizations")
-        .arg_unsupported_mode("debug", "build", "release")
+        .arg_redundant_default_mode("debug", "build", "release")
         .arg_profile("Build artifacts with the specified profile")
         .arg_parallel()
         .arg_target_triple("Build for the target triple")
diff --git a/src/bin/cargo/commands/install.rs b/src/bin/cargo/commands/install.rs
index 57063f11dc8..2e5163bdc94 100644
--- a/src/bin/cargo/commands/install.rs
+++ b/src/bin/cargo/commands/install.rs
@@ -83,7 +83,7 @@ pub fn cli() -> Command {
             "debug",
             "Build in debug mode (with the 'dev' profile) instead of release mode",
         ))
-        .arg_unsupported_mode("release", "install", "debug")
+        .arg_redundant_default_mode("release", "install", "debug")
         .arg_profile("Install artifacts with the specified profile")
         .arg_target_triple("Build for the target triple")
         .arg_target_dir()
diff --git a/src/cargo/util/command_prelude.rs b/src/cargo/util/command_prelude.rs
index 270b558c6c2..dcfabb3c259 100644
--- a/src/cargo/util/command_prelude.rs
+++ b/src/cargo/util/command_prelude.rs
@@ -112,17 +112,15 @@ pub trait CommandExt: Sized {
         self._arg(flag("keep-going", "").value_parser(value_parser).hide(true))
     }
 
-    fn arg_unsupported_mode(
+    fn arg_redundant_default_mode(
         self,
-        want: &'static str,
+        default_mode: &'static str,
         command: &'static str,
-        actual: &'static str,
+        supported_mode: &'static str,
     ) -> Self {
-        let msg = format!(
-            "There is no `--{want}` for `cargo {command}`. Only `--{actual}` is supported."
-        );
+        let msg = format!("`--{default_mode}` is the default for `cargo {command}`; instead `--{supported_mode}` is supported");
         let value_parser = UnknownArgumentValueParser::suggest(msg);
-        self._arg(flag(want, "").value_parser(value_parser).hide(true))
+        self._arg(flag(default_mode, "").value_parser(value_parser).hide(true))
     }
 
     fn arg_targets_all(
diff --git a/tests/testsuite/build.rs b/tests/testsuite/build.rs
index cb8c274939f..1afa83918f0 100644
--- a/tests/testsuite/build.rs
+++ b/tests/testsuite/build.rs
@@ -136,7 +136,7 @@ fn incremental_config() {
 }
 
 #[cargo_test]
-fn cargo_compile_with_unsupported_mode() {
+fn cargo_compile_with_redundant_default_mode() {
     let p = project()
         .file("Cargo.toml", &basic_bin_manifest("foo"))
         .file("src/foo.rs", &main_file(r#""i am foo""#, &[]))
@@ -147,7 +147,7 @@ fn cargo_compile_with_unsupported_mode() {
             "\
 error: unexpected argument '--debug' found
 
-  tip: There is no `--debug` for `cargo build`. Only `--release` is supported.
+  tip: `--debug` is the default for `cargo build`; instead `--release` is supported
 
 Usage: cargo[EXE] build [OPTIONS]
 
diff --git a/tests/testsuite/install.rs b/tests/testsuite/install.rs
index b49cbec315e..0a3670e6c8b 100644
--- a/tests/testsuite/install.rs
+++ b/tests/testsuite/install.rs
@@ -2445,7 +2445,7 @@ fn ambiguous_registry_vs_local_package() {
 }
 
 #[cargo_test]
-fn install_with_unsupported_mode() {
+fn install_with_redundant_default_mode() {
     pkg("foo", "0.0.1");
 
     cargo_process("install foo --release")
@@ -2453,7 +2453,7 @@ fn install_with_unsupported_mode() {
             "\
 error: unexpected argument '--release' found
 
-  tip: There is no `--release` for `cargo install`. Only `--debug` is supported.
+  tip: `--release` is the default for `cargo install`; instead `--debug` is supported
 
 Usage: cargo[EXE] install [OPTIONS] [crate]...