Rollup merge of rust-lang#86478 - ehuss:future-incompat-test, r=oli-obk

Add -Zfuture-incompat-test to assist with testing future-incompat reports.

This adds a `-Zfuture-incompat-test` cli flag to assist with testing future-incompatible reports. This flag causes all lints to be treated as a future-incompatible lint, and will emit a report for them. This is being added so that Cargo's testsuite can reliably test the reporting infrastructure.  Right now, Cargo relies on using array_into_iter as a test subject. Since the breaking "future incompatible" lints are never intended to last forever, this means Cargo's testsuite would always need to keep changing to choose different lints (for example, rust-lang#86330 proposed dropping that moniker for array_into_iter). With this flag, Cargo's tests can trigger any lint and check for the report.

compiler/rustc_interface/src/tests.rs

@@ -633,6 +633,7 @@ fn test_debugging_options_tracking_hash() {
     untracked!(dump_mir_graphviz, true);
     untracked!(emit_future_incompat_report, true);
     untracked!(emit_stack_sizes, true);
+    untracked!(future_incompat_test, true);
     untracked!(hir_stats, true);
     untracked!(identify_regions, true);
     untracked!(incremental_ignore_spans, true);

compiler/rustc_middle/src/lint.rs

@@ -8,7 +8,7 @@ use rustc_hir::HirId;
 use rustc_index::vec::IndexVec;
 use rustc_session::lint::{
     builtin::{self, FORBIDDEN_LINT_GROUPS},
-    FutureIncompatibilityReason, FutureIncompatibleInfo, Level, Lint, LintId,
+    FutureIncompatibilityReason, Level, Lint, LintId,
 };
 use rustc_session::{DiagnosticMessageId, Session};
 use rustc_span::hygiene::MacroKind;
@@ -223,12 +223,12 @@ pub fn struct_lint_level<'s, 'd>(
         let lint_id = LintId::of(lint);
         let future_incompatible = lint.future_incompatible;
 
-        let has_future_breakage = matches!(
-            future_incompatible,
-            Some(FutureIncompatibleInfo {
-                reason: FutureIncompatibilityReason::FutureReleaseErrorReportNow,
-                ..
-            })
+        let has_future_breakage = future_incompatible.map_or(
+            // Default allow lints trigger too often for testing.
+            sess.opts.debugging_opts.future_incompat_test && lint.default_level != Level::Allow,
+            |incompat| {
+                matches!(incompat.reason, FutureIncompatibilityReason::FutureReleaseErrorReportNow)
+            },
         );
 
         let mut err = match (level, span) {

compiler/rustc_session/src/options.rs

@@ -1084,6 +1084,8 @@ options! {
         "set the optimization fuel quota for a crate"),
     function_sections: Option<bool> = (None, parse_opt_bool, [TRACKED],
         "whether each function should go in its own section"),
+    future_incompat_test: bool = (false, parse_bool, [UNTRACKED],
+        "forces all lints to be future incompatible, used for internal testing (default: no)"),
     gcc_ld: Option<LdImpl> = (None, parse_gcc_ld, [TRACKED], "implementation of ld used by cc"),
     graphviz_dark_mode: bool = (false, parse_bool, [UNTRACKED],
         "use dark-themed colors in graphviz output (default: no)"),

src/test/ui/lint/future-incompat-test.rs

@@ -0,0 +1,10 @@
+// compile-flags: -Zfuture-incompat-test -Zemit-future-incompat-report
+// check-pass
+
+// The `-Zfuture-incompat-test flag causes any normal warning to be included
+// in the future-incompatible report. The stderr output here should mention
+// the future incompatible report (as extracted by compiletest).
+
+fn main() {
+    let x = 1;
+}

src/test/ui/lint/future-incompat-test.stderr

@@ -0,0 +1,9 @@
+Future incompatibility report: Future breakage diagnostic:
+warning: unused variable: `x`
+  --> $DIR/future-incompat-test.rs:9:9
+   |
+LL |     let x = 1;
+   |         ^ help: if this is intentional, prefix it with an underscore: `_x`
+   |
+   = note: `-A unused-variables` implied by `-A unused`
+

src/test/ui/proc-macro/group-compat-hack/group-compat-hack.stderr

@@ -81,7 +81,7 @@ LL |     tuple_from_req!(Foo);
 
 warning: 5 warnings emitted
 
-Future incompatibility report: Future breakage date: None, diagnostic:
+Future incompatibility report: Future breakage diagnostic:
 warning: using an old version of `time-macros-impl`
   --> $DIR/time-macros-impl/src/lib.rs:5:32
    |
@@ -99,7 +99,7 @@ LL |     impl_macros!(Foo);
    = note: the `time-macros-impl` crate will stop compiling in futures version of Rust. Please update to the latest version of the `time` crate to avoid breakage
    = note: this warning originates in the macro `impl_macros` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-Future breakage date: None, diagnostic:
+Future breakage diagnostic:
 warning: using an old version of `time-macros-impl`
   --> $DIR/time-macros-impl-0.1.0/src/lib.rs:5:32
    |
@@ -116,7 +116,7 @@ LL |     impl_macros!(Foo);
    = note: the `time-macros-impl` crate will stop compiling in futures version of Rust. Please update to the latest version of the `time` crate to avoid breakage
    = note: this warning originates in the macro `impl_macros` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-Future breakage date: None, diagnostic:
+Future breakage diagnostic:
 warning: using an old version of `js-sys`
   --> $DIR/js-sys-0.3.17/src/lib.rs:5:32
    |
@@ -133,7 +133,7 @@ LL |     arrays!(Foo);
    = note: older versions of the `js-sys` crate will stop compiling in future versions of Rust; please update to `js-sys` v0.3.40 or above
    = note: this warning originates in the macro `arrays` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-Future breakage date: None, diagnostic:
+Future breakage diagnostic:
 warning: using an old version of `actix-web`
   --> $DIR/actix-web/src/extract.rs:5:34
    |
@@ -150,7 +150,7 @@ LL |     tuple_from_req!(Foo);
    = note: the version of `actix-web` you are using might stop compiling in future versions of Rust; please update to the latest version of the `actix-web` crate to avoid breakage
    = note: this warning originates in the macro `tuple_from_req` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-Future breakage date: None, diagnostic:
+Future breakage diagnostic:
 warning: using an old version of `actix-web`
   --> $DIR/actix-web-2.0.0/src/extract.rs:5:34
    |

src/test/ui/proc-macro/issue-73933-procedural-masquerade.stderr

@@ -11,7 +11,7 @@ LL | enum ProceduralMasqueradeDummyType {
 
 warning: 1 warning emitted
 
-Future incompatibility report: Future breakage date: None, diagnostic:
+Future incompatibility report: Future breakage diagnostic:
 warning: using `procedural-masquerade` crate
   --> $DIR/issue-73933-procedural-masquerade.rs:8:6
    |

src/tools/compiletest/src/json.rs

@@ -43,7 +43,6 @@ struct FutureIncompatReport {
 
 #[derive(Deserialize)]
 struct FutureBreakageItem {
-    future_breakage_date: Option<String>,
     diagnostic: Diagnostic,
 }
 
@@ -104,9 +103,7 @@ pub fn extract_rendered(output: &str) -> String {
                                 .into_iter()
                                 .map(|item| {
                                     format!(
-                                        "Future breakage date: {}, diagnostic:\n{}",
-                                        item.future_breakage_date
-                                            .unwrap_or_else(|| "None".to_string()),
+                                        "Future breakage diagnostic:\n{}",
                                         item.diagnostic
                                             .rendered
                                             .unwrap_or_else(|| "Not rendered".to_string())