Address review comments

src/bin/cargo/commands/describe_future_incompatibilities.rs

@@ -1,8 +1,8 @@
 use crate::command_prelude::*;
 use anyhow::anyhow;
 use cargo::core::compiler::future_incompat::{OnDiskReport, FUTURE_INCOMPAT_FILE};
-use cargo::core::nightly_features_allowed;
 use cargo::drop_eprint;
+use cargo::util::CargoResultExt;
 use std::io::Read;
 
 pub fn cli() -> App {
@@ -19,7 +19,7 @@ pub fn cli() -> App {
 }
 
 pub fn exec(config: &mut Config, args: &ArgMatches<'_>) -> CliResult {
-    if !nightly_features_allowed() {
+    if !config.nightly_features_allowed {
         return Err(anyhow!(
             "`cargo describe-future-incompatibilities` can only be used on the nightly channel"
         )
@@ -37,12 +37,19 @@ pub fn exec(config: &mut Config, args: &ArgMatches<'_>) -> CliResult {
     report_file
         .file()
         .read_to_string(&mut file_contents)
-        .map_err(|e| anyhow!("Failed to read report: {:?}", e))?;
-    let on_disk_report: OnDiskReport = serde_json::from_str(&file_contents).unwrap();
+        .chain_err(|| "failed to read report")?;
+    let on_disk_report: OnDiskReport =
+        serde_json::from_str(&file_contents).chain_err(|| "failed to load report")?;
 
     let id = args.value_of("id").unwrap();
     if id != on_disk_report.id {
-        return Err(anyhow!("Expected an id of `{}`, but `{}` was provided on the command line. Your report may have been overwritten by a different one.", on_disk_report.id, id).into());
+        return Err(anyhow!(
+            "Expected an id of `{}`, but `{}` was provided on the command line.\
+                           Your report may have been overwritten by a different one.",
+            on_disk_report.id,
+            id
+        )
+        .into());
     }
 
     drop_eprint!(config, "{}", on_disk_report.report);

src/cargo/core/compiler/future_incompat.rs

@@ -15,7 +15,7 @@ pub struct FutureBreakageItem {
     pub diagnostic: Diagnostic,
 }
 
-/// A diagnostic emitted by the compiler a a JSON message.
+/// A diagnostic emitted by the compiler as a JSON message.
 /// We only care about the 'rendered' field
 #[derive(Serialize, Deserialize)]
 pub struct Diagnostic {

src/cargo/core/compiler/job_queue.rs

@@ -157,7 +157,6 @@ struct DrainState<'cfg> {
 
     /// How many jobs we've finished
     finished: usize,
-    show_future_incompat_report: bool,
     per_crate_future_incompat_reports: Vec<FutureIncompatReportCrate>,
 }
 
@@ -429,7 +428,6 @@ impl<'cfg> JobQueue<'cfg> {
             pending_queue: Vec::new(),
             print: DiagnosticPrinter::new(cx.bcx.config),
             finished: 0,
-            show_future_incompat_report: cx.bcx.build_config.future_incompat_report,
             per_crate_future_incompat_reports: Vec::new(),
         };
 
@@ -613,12 +611,9 @@ impl<'cfg> DrainState<'cfg> {
                 }
             }
             Message::FutureIncompatReport(id, report) => {
-                let unit = self.active[&id].clone();
+                let package_id = self.active[&id].pkg.package_id();
                 self.per_crate_future_incompat_reports
-                    .push(FutureIncompatReportCrate {
-                        package_id: unit.pkg.package_id(),
-                        report,
-                    });
+                    .push(FutureIncompatReportCrate { package_id, report });
             }
             Message::Token(acquired_token) => {
                 let token = acquired_token.chain_err(|| "failed to acquire jobserver token")?;
@@ -820,12 +815,14 @@ impl<'cfg> DrainState<'cfg> {
             let crates_and_versions = self
                 .per_crate_future_incompat_reports
                 .iter()
-                .map(|r| format!("{}", r.package_id))
+                .map(|r| r.package_id.to_string())
                 .collect::<Vec<_>>()
                 .join(", ");
 
-            drop(cx.bcx.config.shell().warn(&format!("the following crates contain code that will be rejected by a future version of Rust: {}",
-                                                     crates_and_versions)));
+            drop(cx.bcx.config.shell().warn(&format!(
+                "the following crates contain code that will be rejected by a future version of Rust: {}",
+                crates_and_versions
+            )));
 
             let mut full_report = String::new();
             let mut rng = thread_rng();
@@ -837,7 +834,10 @@ impl<'cfg> DrainState<'cfg> {
                 .collect();
 
             for report in std::mem::take(&mut self.per_crate_future_incompat_reports) {
-                full_report.push_str(&format!("The crate `{}` currently triggers the following future incompatibility lints:\n", report.package_id));
+                full_report.push_str(&format!(
+                    "The crate `{}` currently triggers the following future incompatibility lints:\n",
+                    report.package_id
+                ));
                 for item in report.report {
                     let rendered = if cx.bcx.config.shell().err_supports_color() {
                         item.diagnostic.rendered
@@ -868,13 +868,14 @@ impl<'cfg> DrainState<'cfg> {
                 })
                 .err();
             if let Some(e) = err {
-                drop(cx.bcx.config.shell().warn(&format!(
-                    "Failed to open on-disk future incompat report: {:?}",
-                    e
-                )));
+                crate::display_warning_with_error(
+                    "failed to write on-disk future incompat report",
+                    &e,
+                    &mut cx.bcx.config.shell(),
+                );
             }
 
-            if self.show_future_incompat_report {
+            if cx.bcx.build_config.future_incompat_report {
                 drop_eprint!(cx.bcx.config, "{}", full_report);
                 drop(cx.bcx.config.shell().note(
                     &format!("this report can be shown with `cargo describe-future-incompatibilities -Z future-incompat-report --id {}`", id)

src/doc/src/reference/unstable.md

@@ -1122,3 +1122,11 @@ The 2021 edition will set the default [resolver version] to "2".
     }
 })();
 </script>
+
+### future incompat report
+* RFC: [#2834](https://github.com/rust-lang/rfcs/blob/master/text/2834-cargo-report-future-incompat.md)
+* rustc Tracking Issue: [#71249](https://github.com/rust-lang/rust/issues/71249)
+
+The `-Z future-incompat-report` flag enables the creation of a future-incompat report
+for all dependencies. This makes users aware if any of their crate's dependencies
+might stop compiling with a future version of Rust.

tests/testsuite/future_incompat_report.rs

@@ -11,7 +11,7 @@ fn no_output_on_stable() {
 
     p.cargo("build")
         .with_stderr_contains("  = note: `#[warn(array_into_iter)]` on by default")
-        .with_stderr_does_not_contain("warning: the following crates contain code that will be rejected by a future version of Rust: `foo` v0.0.0")
+        .with_stderr_does_not_contain("[..]crates[..]")
         .run();
 }
 
@@ -66,7 +66,7 @@ fn test_single_crate() {
             .masquerade_as_nightly_cargo()
             .with_stderr_contains("  = note: `#[warn(array_into_iter)]` on by default")
             .with_stderr_contains("warning: the following crates contain code that will be rejected by a future version of Rust: foo v0.0.0 [..]")
-            .with_stderr_does_not_contain("[..] future incompatibility lints:")
+            .with_stderr_does_not_contain("[..]incompatibility[..]")
             .run();
 
         p.cargo(command).arg("-Zfuture-incompat-report").arg("-Zunstable-options").arg("--future-incompat-report")
@@ -108,25 +108,23 @@ fn test_multi_crate() {
         .build();
 
     for command in &["build", "check", "rustc"] {
-        p.cargo(&format!("{} -Z future-incompat-report", command))
+        p.cargo(command).arg("-Zfuture-incompat-report")
             .masquerade_as_nightly_cargo()
-            .with_stderr_does_not_contain("  = note: `#[warn(array_into_iter)]` on by default")
+            .with_stderr_does_not_contain("[..]array_into_iter[..]")
             .with_stderr_contains("warning: the following crates contain code that will be rejected by a future version of Rust: first-dep v0.0.1, second-dep v0.0.2")
-            .with_stderr_does_not_contain("The crate `foo` v0.0.0 currently triggers the following future incompatibility lints:")
+            // Check that we don't have the 'triggers' message shown at the bottom of this loop
+            .with_stderr_does_not_contain("[..]triggers[..]")
             .run();
 
         p.cargo("describe-future-incompatibilities -Z future-incompat-report --id bad-id")
             .masquerade_as_nightly_cargo()
-            .with_stderr_does_not_contain("  = note: `#[warn(array_into_iter)]` on by default")
             .with_stderr_contains("error: Expected an id of [..]")
-            .with_stderr_does_not_contain("The crate `first-dep v0.0.1` currently triggers the following future incompatibility lints:")
-            .with_stderr_does_not_contain("The crate `second-dep v0.0.2` currently triggers the following future incompatibility lints:")
+            .with_stderr_does_not_contain("[..]triggers[..]")
             .with_status(101)
             .run();
 
-        p.cargo(&format!("{} -Z unstable-options -Z future-incompat-report --future-incompat-report", command))
+        p.cargo(command).arg("-Zunstable-options").arg("-Zfuture-incompat-report").arg("--future-incompat-report")
             .masquerade_as_nightly_cargo()
-            .with_stderr_does_not_contain("  = note: `#[warn(array_into_iter)]` on by default")
             .with_stderr_contains("warning: the following crates contain code that will be rejected by a future version of Rust: first-dep v0.0.1, second-dep v0.0.2")
             .with_stderr_contains("The crate `first-dep v0.0.1` currently triggers the following future incompatibility lints:")
             .with_stderr_contains("The crate `second-dep v0.0.2` currently triggers the following future incompatibility lints:")
@@ -158,7 +156,6 @@ fn test_multi_crate() {
 
     p.cargo(&format!("describe-future-incompatibilities -Z future-incompat-report --id {}", id))
         .masquerade_as_nightly_cargo()
-        .with_stderr_does_not_contain("warning: Expected an id of [..]")
         .with_stderr_contains("The crate `first-dep v0.0.1` currently triggers the following future incompatibility lints:")
         .with_stderr_contains("The crate `second-dep v0.0.2` currently triggers the following future incompatibility lints:")
         .run();