Stabilize terminal-width

src/cargo/core/compiler/mod.rs

@@ -899,22 +899,8 @@ fn add_error_format_and_color(cx: &Context<'_, '_>, cmd: &mut ProcessBuilder) {
     cmd.arg(json);
 
     let config = cx.bcx.config;
-    if config.nightly_features_allowed {
-        match (
-            config.cli_unstable().terminal_width,
-            config.shell().err_width().diagnostic_terminal_width(),
-        ) {
-            // Terminal width explicitly provided - only useful for testing.
-            (Some(Some(width)), _) => {
-                cmd.arg(format!("--diagnostic-width={}", width));
-            }
-            // Terminal width was not explicitly provided but flag was provided - common case.
-            (Some(None), Some(width)) => {
-                cmd.arg(format!("--diagnostic-width={}", width));
-            }
-            // User didn't opt-in.
-            _ => (),
-        }
+    if let Some(width) = config.shell().err_width().diagnostic_terminal_width() {
+        cmd.arg(format!("--diagnostic-width={width}"));
     }
 }
 

src/cargo/core/features.rs

@@ -686,7 +686,6 @@ unstable_cli_options!(
     target_applies_to_host: bool = ("Enable the `target-applies-to-host` key in the .cargo/config.toml file"),
     rustdoc_map: bool = ("Allow passing external documentation mappings to rustdoc"),
     separate_nightlies: bool = (HIDDEN),
-    terminal_width: Option<Option<usize>>  = ("Provide a terminal width to rustc for error truncation"),
     publish_timeout: bool = ("Enable the `publish.timeout` key in .cargo/config.toml file"),
     unstable_options: bool = ("Allow the usage of unstable options"),
     skip_rustdoc_fingerprint: bool = (HIDDEN),
@@ -749,6 +748,9 @@ const STABILIZED_TIMINGS: &str = "The -Ztimings option has been stabilized as --
 
 const STABILISED_MULTITARGET: &str = "Multiple `--target` options are now always available.";
 
+const STABILIZED_TERMINAL_WIDTH: &str =
+    "The -Zterminal-width option is now always enabled for terminal output.";
+
 fn deserialize_build_std<'de, D>(deserializer: D) -> Result<Option<Vec<String>>, D::Error>
 where
     D: serde::Deserializer<'de>,
@@ -862,16 +864,6 @@ impl CliUnstable {
             Ok(true)
         }
 
-        fn parse_usize_opt(value: Option<&str>) -> CargoResult<Option<usize>> {
-            Ok(match value {
-                Some(value) => match value.parse::<usize>() {
-                    Ok(value) => Some(value),
-                    Err(e) => bail!("expected a number, found: {}", e),
-                },
-                None => None,
-            })
-        }
-
         let mut stabilized_warn = |key: &str, version: &str, message: &str| {
             warnings.push(format!(
                 "flag `-Z {}` has been stabilized in the {} release, \
@@ -955,7 +947,7 @@ impl CliUnstable {
             "separate-nightlies" => self.separate_nightlies = parse_empty(k, v)?,
             "multitarget" => stabilized_warn(k, "1.64", STABILISED_MULTITARGET),
             "rustdoc-map" => self.rustdoc_map = parse_empty(k, v)?,
-            "terminal-width" => self.terminal_width = Some(parse_usize_opt(v)?),
+            "terminal-width" => stabilized_warn(k, "1.68", STABILIZED_TERMINAL_WIDTH),
             "sparse-registry" => self.sparse_registry = parse_empty(k, v)?,
             "registry-auth" => self.registry_auth = parse_empty(k, v)?,
             "namespaced-features" => stabilized_warn(k, "1.60", STABILISED_NAMESPACED_FEATURES),

src/cargo/core/shell.rs

@@ -14,9 +14,12 @@ pub enum TtyWidth {
 }
 
 impl TtyWidth {
-    /// Returns the width provided with `-Z terminal-width` to rustc to truncate diagnostics with
-    /// long lines.
+    /// Returns the width of the terminal to use for diagnostics (which is
+    /// relayed to rustc via `--diagnostic-width`).
     pub fn diagnostic_terminal_width(&self) -> Option<usize> {
+        if let Ok(width) = std::env::var("__CARGO_TEST_TTY_WIDTH_DO_NOT_USE_THIS") {
+            return Some(width.parse().unwrap());
+        }
         match *self {
             TtyWidth::NoTty | TtyWidth::Guess(_) => None,
             TtyWidth::Known(width) => Some(width),

src/doc/src/reference/unstable.md

@@ -70,7 +70,6 @@ Each new feature described below should explain how to use it.
     * [public-dependency](#public-dependency) — Allows dependencies to be classified as either public or private.
 * Output behavior
     * [out-dir](#out-dir) — Adds a directory where artifacts are copied to.
-    * [terminal-width](#terminal-width) — Tells rustc the width of the terminal so that long diagnostic messages can be truncated to be more readable.
     * [Different binary name](#different-binary-name) — Assign a name to the built binary that is separate from the crate name.
 * Compile behavior
     * [mtime-on-use](#mtime-on-use) — Updates the last-modified timestamp on every dependency every time it is used, to provide a mechanism to delete unused artifacts.
@@ -723,43 +722,6 @@ The default value is `"remote"`.
 
 The value may also take a URL for a custom location.
 
-### terminal-width
-
-* Tracking Issue: [#84673](https://github.com/rust-lang/rust/issues/84673)
-
-This feature provides a new flag, `-Z terminal-width`, which is used to pass
-a terminal width to `rustc` so that error messages containing long lines
-can be intelligently truncated.
-
-For example, passing `-Z terminal-width=20` (an arbitrarily low value) might
-produce the following error:
-
-```text
-error[E0308]: mismatched types
-  --> src/main.rs:2:17
-  |
-2 | ..._: () = 42;
-  |       --   ^^ expected `()`, found integer
-  |       |
-  |       expected due to this
-
-error: aborting due to previous error
-```
-
-In contrast, without `-Z terminal-width`, the error would look as shown below:
-
-```text
-error[E0308]: mismatched types
- --> src/main.rs:2:17
-  |
-2 |     let _: () = 42;
-  |            --   ^^ expected `()`, found integer
-  |            |
-  |            expected due to this
-
-error: aborting due to previous error
-```
-
 ### per-package-target
 * Tracking Issue: [#9406](https://github.com/rust-lang/cargo/pull/9406)
 * Original Pull Request: [#9030](https://github.com/rust-lang/cargo/pull/9030)
@@ -1447,3 +1409,9 @@ See [workspace.package](workspaces.md#the-package-table),
 [workspace.dependencies](workspaces.md#the-dependencies-table),
 and [inheriting-a-dependency-from-a-workspace](specifying-dependencies.md#inheriting-a-dependency-from-a-workspace)
 for more information.
+
+### terminal-width
+
+The `-Z terminal-width` option has been stabilized in the 1.68 release.
+The terminal width is always passed to the compiler when running from a
+terminal where Cargo can automatically detect the width.

tests/testsuite/build.rs

@@ -6130,23 +6130,28 @@ fn target_directory_backup_exclusion() {
     assert!(!&cachedir_tag.is_file());
 }
 
-#[cargo_test(>=1.64, reason = "--diagnostic-width is stabilized in 1.64")]
+#[cargo_test]
 fn simple_terminal_width() {
     let p = project()
         .file(
             "src/lib.rs",
             r#"
-                fn main() {
+                pub fn foo() {
                     let _: () = 42;
                 }
             "#,
         )
         .build();
 
-    p.cargo("build -Zterminal-width=20")
-        .masquerade_as_nightly_cargo(&["terminal-width"])
+    p.cargo("build -v")
+        .env("__CARGO_TEST_TTY_WIDTH_DO_NOT_USE_THIS", "20")
         .with_status(101)
-        .with_stderr_contains("3 | ..._: () = 42;")
+        .with_stderr_contains("[RUNNING] `rustc [..]--diagnostic-width=20[..]")
+        .run();
+
+    p.cargo("doc -v")
+        .env("__CARGO_TEST_TTY_WIDTH_DO_NOT_USE_THIS", "20")
+        .with_stderr_contains("[RUNNING] `rustdoc [..]--diagnostic-width=20[..]")
         .run();
 }