Re-implement a type-size based limit

Author: compiler-errors

compiler/rustc_codegen_cranelift/src/abi/mod.rs

@@ -370,9 +370,14 @@ pub(crate) fn codegen_terminator_call<'tcx>(
 
     // Handle special calls like intrinsics and empty drop glue.
     let instance = if let ty::FnDef(def_id, fn_args) = *func.layout().ty.kind() {
-        let instance =
-            ty::Instance::expect_resolve(fx.tcx, ty::ParamEnv::reveal_all(), def_id, fn_args)
-                .polymorphize(fx.tcx);
+        let instance = ty::Instance::expect_resolve(
+            fx.tcx,
+            ty::ParamEnv::reveal_all(),
+            def_id,
+            fn_args,
+            Some(source_info.span),
+        )
+        .polymorphize(fx.tcx);
 
         if is_call_from_compiler_builtins_to_upstream_monomorphization(fx.tcx, instance) {
             if target.is_some() {

compiler/rustc_codegen_cranelift/src/main_shim.rs

@@ -121,6 +121,7 @@ pub(crate) fn maybe_create_entry_wrapper(
                     ParamEnv::reveal_all(),
                     report.def_id,
                     tcx.mk_args(&[GenericArg::from(main_ret_ty)]),
+                    None,
                 )
                 .polymorphize(tcx);
 
@@ -146,6 +147,7 @@ pub(crate) fn maybe_create_entry_wrapper(
                     ParamEnv::reveal_all(),
                     start_def_id,
                     tcx.mk_args(&[main_ret_ty.into()]),
+                    None,
                 )
                 .polymorphize(tcx);
                 let start_func_id = import_function(tcx, m, start_instance);

compiler/rustc_codegen_gcc/src/context.rs

@@ -483,6 +483,7 @@ impl<'gcc, 'tcx> MiscMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
                     ty::ParamEnv::reveal_all(),
                     def_id,
                     ty::List::empty(),
+                    None,
                 );
 
                 let symbol_name = tcx.symbol_name(instance).name;

compiler/rustc_codegen_llvm/src/context.rs

@@ -566,6 +566,7 @@ impl<'ll, 'tcx> MiscMethods<'tcx> for CodegenCx<'ll, 'tcx> {
                 ty::ParamEnv::reveal_all(),
                 def_id,
                 ty::List::empty(),
+                None,
             )),
             _ => {
                 let name = name.unwrap_or("rust_eh_personality");

compiler/rustc_codegen_ssa/src/base.rs

@@ -468,6 +468,7 @@ pub fn maybe_create_entry_wrapper<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
                 ty::ParamEnv::reveal_all(),
                 start_def_id,
                 cx.tcx().mk_args(&[main_ret_ty.into()]),
+                None,
             );
             let start_fn = cx.get_fn_addr(start_instance);
 

compiler/rustc_codegen_ssa/src/mir/block.rs

@@ -843,6 +843,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                         ty::ParamEnv::reveal_all(),
                         def_id,
                         args,
+                        Some(fn_span),
                     )
                     .polymorphize(bx.tcx()),
                 ),

compiler/rustc_const_eval/src/const_eval/machine.rs

@@ -252,6 +252,7 @@ impl<'tcx> CompileTimeEvalContext<'tcx> {
                 ty::ParamEnv::reveal_all(),
                 const_def_id,
                 instance.args,
+                Some(self.find_closest_untracked_caller_location()),
             );
 
             return Ok(Some(new_instance));

compiler/rustc_const_eval/src/interpret/terminator.rs

@@ -871,13 +871,12 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                         ty::ExistentialTraitRef::erase_self_ty(tcx, virtual_trait_ref);
                     let concrete_trait_ref = existential_trait_ref.with_self_ty(tcx, dyn_ty);
 
-                    let concrete_method = Instance::resolve_for_vtable(
+                    let concrete_method = Instance::expect_resolve_for_vtable(
                         tcx,
                         self.param_env,
                         def_id,
                         instance.args.rebase_onto(tcx, trait_def_id, concrete_trait_ref.args),
-                    )
-                    .unwrap();
+                    );
                     assert_eq!(fn_inst, concrete_method);
                 }
 

compiler/rustc_middle/messages.ftl

@@ -41,6 +41,9 @@ middle_cannot_be_normalized =
 middle_conflict_types =
     this expression supplies two conflicting concrete types for the same opaque type
 
+middle_consider_type_length_limit =
+    consider adding a `#![type_length_limit="{$type_length}"]` attribute to your crate
+
 middle_const_eval_non_int =
     constant evaluation of enum discriminant resulted in non-integer
 
@@ -94,8 +97,11 @@ middle_strict_coherence_needs_negative_coherence =
     to use `strict_coherence` on this trait, the `with_negative_coherence` feature must be enabled
     .label = due to this attribute
 
+middle_type_length_limit = reached the type-length limit while instantiating `{$shrunk}`
+
 middle_unknown_layout =
     the type `{$ty}` has an unknown layout
 
 middle_values_too_big =
     values of the type `{$ty}` are too big for the current architecture
+middle_written_to_path = the full type name has been written to '{$path}'

compiler/rustc_middle/src/error.rs

@@ -1,4 +1,5 @@
 use std::fmt;
+use std::path::PathBuf;
 
 use rustc_errors::{codes::*, DiagArgName, DiagArgValue, DiagMessage};
 use rustc_macros::{Diagnostic, Subdiagnostic};
@@ -149,3 +150,16 @@ pub struct ErroneousConstant {
 
 /// Used by `rustc_const_eval`
 pub use crate::fluent_generated::middle_adjust_for_foreign_abi_error;
+
+#[derive(Diagnostic)]
+#[diag(middle_type_length_limit)]
+#[help(middle_consider_type_length_limit)]
+pub struct TypeLengthLimit {
+    #[primary_span]
+    pub span: Span,
+    pub shrunk: String,
+    #[note(middle_written_to_path)]
+    pub was_written: Option<()>,
+    pub path: PathBuf,
+    pub type_length: usize,
+}