impl new way to generate the compiler suggestion

Signed-off-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>

compiler/rustc_expand/messages.ftl

@@ -23,6 +23,10 @@ expand_duplicate_matcher_binding = duplicate matcher binding
     .label = duplicate binding
     .label2 = previous binding
 
+expand_expansion_growth_limit_reached =
+    expansion grow limit reached while expanding `{$descr}`
+    .help = consider increasing the expansion grow limit by adding a `#![expansion_growth_limit = "{$suggested_limit}"]` attribute to your crate (`{$crate_name}`)
+
 expand_expected_comma_in_list =
     expected token: `,`
 

compiler/rustc_expand/src/errors.rs

@@ -212,6 +212,17 @@ pub(crate) struct RecursionLimitReached<'a> {
     pub crate_name: &'a str,
 }
 
+#[derive(Diagnostic)]
+#[diag(expand_expansion_growth_limit_reached)]
+#[help]
+pub(crate) struct ExpansionGrowthLimitReached<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub descr: String,
+    pub suggested_limit: Limit,
+    pub crate_name: &'a str,
+}
+
 #[derive(Diagnostic)]
 #[diag(expand_malformed_feature_attribute, code = "E0556")]
 pub(crate) struct MalformedFeatureAttribute {

compiler/rustc_expand/src/expand.rs

@@ -1,8 +1,8 @@
 use crate::base::*;
 use crate::config::StripUnconfigured;
 use crate::errors::{
-    IncompleteParse, RecursionLimitReached, RemoveExprNotSupported, RemoveNodeNotSupported,
-    UnsupportedKeyValue, WrongFragmentKind,
+    ExpansionGrowthLimitReached, IncompleteParse, RecursionLimitReached, RemoveExprNotSupported,
+    RemoveNodeNotSupported, UnsupportedKeyValue, WrongFragmentKind,
 };
 use crate::hygiene::SyntaxContext;
 use crate::mbe::diagnostics::annotate_err_with_kind;
@@ -628,20 +628,12 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
             limit => limit * 2,
         };
 
-        self.cx
-            .struct_span_err(
-                expn_data.call_site,
-                &format!(
-                    "expansion grow limit reached while expanding `{}`",
-                    expn_data.kind.descr()
-                ),
-            )
-            .help(&format!(
-                "consider increasing the expansion grow limit by adding a \
-                 `#![expansion_growth_limit = \"{}\"]` attribute to your crate (`{}`)",
-                suggested_limit, self.cx.ecfg.crate_name,
-            ))
-            .emit();
+        self.cx.emit_err(ExpansionGrowthLimitReached {
+            span: expn_data.call_site,
+            descr: expn_data.kind.descr(),
+            suggested_limit,
+            crate_name: &self.cx.ecfg.crate_name,
+        });
         self.cx.trace_macros_diag();
     }
 
@@ -663,7 +655,6 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
 
             // Reduce the recursion limit by half each time it triggers.
             self.cx.reduced_recursion_limit = Some(expansion_limit / 2);
-
             return Err(());
         }
         Ok(())
@@ -697,11 +688,9 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                     self.parse_ast_fragment(tok_result, fragment_kind, &mac.path, span)
                 }
                 SyntaxExtensionKind::LegacyBang(expander) => {
-                    if self.reduce_expansion_growth_limit(mac.args.inner_tokens().len()).is_err() {
+                    if self.reduce_expansion_growth_limit(mac.args.tokens.len()).is_err() {
                         return ExpandResult::Ready(fragment_kind.dummy(span));
                     }
-                    let prev = self.cx.current_expansion.prior_type_ascription;
-                    self.cx.current_expansion.prior_type_ascription = mac.prior_type_ascription;
                     let tok_result = expander.expand(self.cx, span, mac.args.tokens.clone());
                     let result = if let Some(result) = fragment_kind.make_from(tok_result) {
                         result
@@ -2027,7 +2016,7 @@ impl<'feat> ExpansionConfig<'feat> {
             crate_name,
             features: None,
             recursion_limit: Limit::new(1024),
-            expansion_growth_limit: Limit::new(6000),
+            expansion_growth_limit: Limit::new(1000000),
             trace_mac: false,
             should_test: false,
             span_debug: false,

compiler/rustc_middle/src/middle/limits.rs

@@ -42,7 +42,7 @@ pub fn get_recursion_limit(krate_attrs: &[Attribute], sess: &Session) -> Limit {
 }
 
 pub fn get_expansion_growth_limit(krate_attrs: &[Attribute], sess: &Session) -> Limit {
-    get_limit(krate_attrs, sess, sym::expansion_growth_limit, 6000)
+    get_limit(krate_attrs, sess, sym::expansion_growth_limit, 1000000)
 }
 
 fn get_limit(krate_attrs: &[Attribute], sess: &Session, name: Symbol, default: usize) -> Limit {

compiler/rustc_session/src/session.rs

@@ -128,8 +128,6 @@ pub struct Limits {
     pub move_size_limit: Limit,
     /// The maximum length of types during monomorphization.
     pub type_length_limit: Limit,
-    /// The maximum blocks a const expression can evaluate.
-    pub const_eval_limit: Limit,
     /// The maximum tokens limit for potentially infinitely resolving
     /// a macros that add infinite tokens inside the buffer.
     pub expansion_growth_limit: Limit,

tests/ui/limits/issue-95698.rs

@@ -1,6 +1,6 @@
 // check-fail
 
-/// issue #95698
+// issue #95698
 macro_rules! from_cow_impls {
     ($( $from: ty ),+ $(,)? ) => {
         // recursion call

tests/ui/limits/issue-95698.stderr

@@ -12,7 +12,7 @@ LL | |     Vec<u8>, /*callback,*/
 LL | | );
    | |_- in this macro invocation
    |
-   = help: consider increasing the expansion grow limit by adding a `#![expansion_growth_limit = "12000"]` attribute to your crate (`issue_95698`)
+   = help: consider increasing the expansion grow limit by adding a `#![expansion_growth_limit = "2000000"]` attribute to your crate (`issue_95698`)
    = note: this error originates in the macro `from_cow_impls` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to previous error

tests/ui/mir/issue-29227.rs

@@ -1,4 +1,3 @@
-#![expansion_growth_limit = "16000"]
 // run-pass
 // ignore-tidy-linelength