Auto merge of #105233 - mejrs:always_eager, r=estebank

Always evaluate vecs of subdiagnostics eagerly

See https://rust-lang.zulipchat.com/#narrow/stream/336883-i18n/topic/.23100717.20lists!/near/310186705 for context

6 files changed, 48 insertions, 57 deletions

diff --git a/compiler/rustc_infer/src/errors/mod.rs b/compiler/rustc_infer/src/errors/mod.rs
index 74c4c65cc17..c4f11472d55 100644
--- a/compiler/rustc_infer/src/errors/mod.rs
+++ b/compiler/rustc_infer/src/errors/mod.rs
@@ -517,6 +517,6 @@ pub struct MismatchedStaticLifetime<'a> {
     pub expl: Option<note_and_explain::RegionExplanation<'a>>,
     #[subdiagnostic]
     pub does_not_outlive_static_from_impl: DoesNotOutliveStaticFromImpl,
-    #[subdiagnostic(eager)]
+    #[subdiagnostic]
     pub implicit_static_lifetimes: Vec<ImplicitStaticLifetimeSubdiag>,
 }
diff --git a/compiler/rustc_macros/src/diagnostics/diagnostic_builder.rs b/compiler/rustc_macros/src/diagnostics/diagnostic_builder.rs
index 9f2ac5112f1..82f6812026a 100644
--- a/compiler/rustc_macros/src/diagnostics/diagnostic_builder.rs
+++ b/compiler/rustc_macros/src/diagnostics/diagnostic_builder.rs
@@ -372,46 +372,21 @@ impl<'a> DiagnosticDeriveVariantBuilder<'a> {
                 }
             }
             (Meta::Path(_), "subdiagnostic") => {
-                return Ok(quote! { #diag.subdiagnostic(#binding); });
+                if FieldInnerTy::from_type(&info.binding.ast().ty).will_iterate() {
+                    let DiagnosticDeriveKind::Diagnostic { handler } = &self.parent.kind else {
+                        // No eager translation for lints.
+                        return Ok(quote! { #diag.subdiagnostic(#binding); });
+                    };
+                    return Ok(quote! { #diag.eager_subdiagnostic(#handler, #binding); });
+                } else {
+                    return Ok(quote! { #diag.subdiagnostic(#binding); });
+                }
             }
-            (Meta::NameValue(_), "subdiagnostic") => {
+            (Meta::List(_), "subdiagnostic") => {
                 throw_invalid_attr!(attr, &meta, |diag| {
-                    diag.help("`eager` is the only supported nested attribute for `subdiagnostic`")
+                    diag.help("`subdiagnostic` does not support nested attributes")
                 })
             }
-            (Meta::List(MetaList { ref nested, .. }), "subdiagnostic") => {
-                if nested.len() != 1 {
-                    throw_invalid_attr!(attr, &meta, |diag| {
-                        diag.help(
-                            "`eager` is the only supported nested attribute for `subdiagnostic`",
-                        )
-                    })
-                }
-
-                let handler = match &self.parent.kind {
-                    DiagnosticDeriveKind::Diagnostic { handler } => handler,
-                    DiagnosticDeriveKind::LintDiagnostic => {
-                        throw_invalid_attr!(attr, &meta, |diag| {
-                            diag.help("eager subdiagnostics are not supported on lints")
-                        })
-                    }
-                };
-
-                let nested_attr = nested.first().expect("pop failed for single element list");
-                match nested_attr {
-                    NestedMeta::Meta(meta @ Meta::Path(_))
-                        if meta.path().segments.last().unwrap().ident.to_string().as_str()
-                            == "eager" =>
-                    {
-                        return Ok(quote! { #diag.eager_subdiagnostic(#handler, #binding); });
-                    }
-                    _ => {
-                        throw_invalid_nested_attr!(attr, nested_attr, |diag| {
-                            diag.help("`eager` is the only supported nested attribute for `subdiagnostic`")
-                        })
-                    }
-                }
-            }
             _ => (),
         }
 
diff --git a/compiler/rustc_query_system/src/error.rs b/compiler/rustc_query_system/src/error.rs
index 7a20eaceba0..cf2f04c7486 100644
--- a/compiler/rustc_query_system/src/error.rs
+++ b/compiler/rustc_query_system/src/error.rs
@@ -49,7 +49,7 @@ pub struct Cycle {
     #[primary_span]
     pub span: Span,
     pub stack_bottom: String,
-    #[subdiagnostic(eager)]
+    #[subdiagnostic]
     pub cycle_stack: Vec<CycleStack>,
     #[subdiagnostic]
     pub stack_count: StackCount,
diff --git a/compiler/rustc_session/src/errors.rs b/compiler/rustc_session/src/errors.rs
index 4266430c4c6..25d84506efa 100644
--- a/compiler/rustc_session/src/errors.rs
+++ b/compiler/rustc_session/src/errors.rs
@@ -176,7 +176,7 @@ impl ExprParenthesesNeeded {
 #[derive(Diagnostic)]
 #[diag(session_skipping_const_checks)]
 pub struct SkippingConstChecks {
-    #[subdiagnostic(eager)]
+    #[subdiagnostic]
     pub unleashed_features: Vec<UnleashedFeatureHelp>,
 }
 
diff --git a/src/test/ui-fulldeps/session-diagnostic/diagnostic-derive.rs b/src/test/ui-fulldeps/session-diagnostic/diagnostic-derive.rs
index cb4cd466590..c19b639a8d5 100644
--- a/src/test/ui-fulldeps/session-diagnostic/diagnostic-derive.rs
+++ b/src/test/ui-fulldeps/session-diagnostic/diagnostic-derive.rs
@@ -683,7 +683,7 @@ struct RawIdentDiagnosticArg {
 #[diag(compiletest_example)]
 struct SubdiagnosticBad {
     #[subdiagnostic(bad)]
-    //~^ ERROR `#[subdiagnostic(bad)]` is not a valid attribute
+    //~^ ERROR `#[subdiagnostic(...)]` is not a valid attribute
     note: Note,
 }
 
@@ -707,7 +707,7 @@ struct SubdiagnosticBadTwice {
 #[diag(compiletest_example)]
 struct SubdiagnosticBadLitStr {
     #[subdiagnostic("bad")]
-    //~^ ERROR `#[subdiagnostic("...")]` is not a valid attribute
+    //~^ ERROR `#[subdiagnostic(...)]` is not a valid attribute
     note: Note,
 }
 
@@ -723,6 +723,7 @@ struct SubdiagnosticEagerLint {
 #[diag(compiletest_example)]
 struct SubdiagnosticEagerCorrect {
     #[subdiagnostic(eager)]
+    //~^ ERROR `#[subdiagnostic(...)]` is not a valid attribute
     note: Note,
 }
 
@@ -743,6 +744,7 @@ pub(crate) struct SubdiagnosticWithSuggestion {
 #[diag(compiletest_example)]
 struct SubdiagnosticEagerSuggestion {
     #[subdiagnostic(eager)]
+    //~^ ERROR `#[subdiagnostic(...)]` is not a valid attribute
     sub: SubdiagnosticWithSuggestion,
 }
 
diff --git a/src/test/ui-fulldeps/session-diagnostic/diagnostic-derive.stderr b/src/test/ui-fulldeps/session-diagnostic/diagnostic-derive.stderr
index 1b7ef4e4f19..f39d32a221c 100644
--- a/src/test/ui-fulldeps/session-diagnostic/diagnostic-derive.stderr
+++ b/src/test/ui-fulldeps/session-diagnostic/diagnostic-derive.stderr
@@ -533,21 +533,19 @@ LL | #[label]
    |
    = help: `#[label]` and `#[suggestion]` can only be applied to fields
 
-error: `#[subdiagnostic(bad)]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:685:21
+error: `#[subdiagnostic(...)]` is not a valid attribute
+  --> $DIR/diagnostic-derive.rs:685:5
    |
 LL |     #[subdiagnostic(bad)]
-   |                     ^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^
    |
-   = help: `eager` is the only supported nested attribute for `subdiagnostic`
+   = help: `subdiagnostic` does not support nested attributes
 
 error: `#[subdiagnostic = ...]` is not a valid attribute
   --> $DIR/diagnostic-derive.rs:693:5
    |
 LL |     #[subdiagnostic = "bad"]
    |     ^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: `eager` is the only supported nested attribute for `subdiagnostic`
 
 error: `#[subdiagnostic(...)]` is not a valid attribute
   --> $DIR/diagnostic-derive.rs:701:5
@@ -555,15 +553,15 @@ error: `#[subdiagnostic(...)]` is not a valid attribute
 LL |     #[subdiagnostic(bad, bad)]
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = help: `eager` is the only supported nested attribute for `subdiagnostic`
+   = help: `subdiagnostic` does not support nested attributes
 
-error: `#[subdiagnostic("...")]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:709:21
+error: `#[subdiagnostic(...)]` is not a valid attribute
+  --> $DIR/diagnostic-derive.rs:709:5
    |
 LL |     #[subdiagnostic("bad")]
-   |                     ^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = help: `eager` is the only supported nested attribute for `subdiagnostic`
+   = help: `subdiagnostic` does not support nested attributes
 
 error: `#[subdiagnostic(...)]` is not a valid attribute
   --> $DIR/diagnostic-derive.rs:717:5
@@ -571,22 +569,38 @@ error: `#[subdiagnostic(...)]` is not a valid attribute
 LL |     #[subdiagnostic(eager)]
    |     ^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = help: eager subdiagnostics are not supported on lints
+   = help: `subdiagnostic` does not support nested attributes
+
+error: `#[subdiagnostic(...)]` is not a valid attribute
+  --> $DIR/diagnostic-derive.rs:725:5
+   |
+LL |     #[subdiagnostic(eager)]
+   |     ^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: `subdiagnostic` does not support nested attributes
+
+error: `#[subdiagnostic(...)]` is not a valid attribute
+  --> $DIR/diagnostic-derive.rs:746:5
+   |
+LL |     #[subdiagnostic(eager)]
+   |     ^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: `subdiagnostic` does not support nested attributes
 
 error: expected at least one string literal for `code(...)`
-  --> $DIR/diagnostic-derive.rs:775:18
+  --> $DIR/diagnostic-derive.rs:777:18
    |
 LL |     #[suggestion(code())]
    |                  ^^^^^^
 
 error: `code(...)` must contain only string literals
-  --> $DIR/diagnostic-derive.rs:783:23
+  --> $DIR/diagnostic-derive.rs:785:23
    |
 LL |     #[suggestion(code(foo))]
    |                       ^^^
 
 error: `code = "..."`/`code(...)` must contain only string literals
-  --> $DIR/diagnostic-derive.rs:791:18
+  --> $DIR/diagnostic-derive.rs:793:18
    |
 LL |     #[suggestion(code = 3)]
    |                  ^^^^^^^^
@@ -662,7 +676,7 @@ note: required by a bound in `DiagnosticBuilder::<'a, G>::set_arg`
   --> $COMPILER_DIR/rustc_errors/src/diagnostic_builder.rs:LL:CC
    = note: this error originates in the derive macro `Diagnostic` which comes from the expansion of the macro `forward` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: aborting due to 83 previous errors
+error: aborting due to 85 previous errors
 
 Some errors have detailed explanations: E0277, E0425.
 For more information about an error, try `rustc --explain E0277`.