Rollup merge of #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, #86330 proposed dropping that moniker for array_into_iter). With this flag, Cargo's tests can trigger any lint and check for the report.

8 files changed, 36 insertions, 17 deletions

diff --git a/compiler/rustc_interface/src/tests.rs b/compiler/rustc_interface/src/tests.rs
index a053253ec16..5a362a37f2b 100644
--- a/compiler/rustc_interface/src/tests.rs
+++ b/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);
diff --git a/compiler/rustc_middle/src/lint.rs b/compiler/rustc_middle/src/lint.rs
index 484e30027e5..848e60fe134 100644
--- a/compiler/rustc_middle/src/lint.rs
+++ b/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) {
diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs
index 4c40d0c367e..474cd86f43b 100644
--- a/compiler/rustc_session/src/options.rs
+++ b/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)"),
diff --git a/src/test/ui/lint/future-incompat-test.rs b/src/test/ui/lint/future-incompat-test.rs
new file mode 100644
index 00000000000..ce8c118dab2
--- /dev/null
+++ b/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;
+}
diff --git a/src/test/ui/lint/future-incompat-test.stderr b/src/test/ui/lint/future-incompat-test.stderr
new file mode 100644
index 00000000000..52674a84384
--- /dev/null
+++ b/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`
+
diff --git a/src/test/ui/proc-macro/group-compat-hack/group-compat-hack.stderr b/src/test/ui/proc-macro/group-compat-hack/group-compat-hack.stderr
index e764480e8e5..070b0667213 100644
--- a/src/test/ui/proc-macro/group-compat-hack/group-compat-hack.stderr
+++ b/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
    |
diff --git a/src/test/ui/proc-macro/issue-73933-procedural-masquerade.stderr b/src/test/ui/proc-macro/issue-73933-procedural-masquerade.stderr
index 0b930705e35..4d6edab08e2 100644
--- a/src/test/ui/proc-macro/issue-73933-procedural-masquerade.stderr
+++ b/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
    |
diff --git a/src/tools/compiletest/src/json.rs b/src/tools/compiletest/src/json.rs
index 8d23227fdb8..dc6d67983c5 100644
--- a/src/tools/compiletest/src/json.rs
+++ b/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())