Remove mono item collection strategy override from -Zprint-mono-items

Previously `-Zprint-mono-items` would override the mono item collection
strategy. When debugging one doesn't want to change the behaviour, so
this was counter productive. Additionally, the produced behaviour was
artificial and might never arise without using the option in the first
place (`-Zprint-mono-items=eager` without `-Clink-dead-code`).  Finally,
the option was incorrectly marked as `UNTRACKED`.

Resolve those issues, by turning `-Zprint-mono-items` into a boolean
flag that prints results of mono item collection without changing the
behaviour of mono item collection.

For codegen-units test incorporate `-Zprint-mono-items` flag directly
into compiletest tool.

Test changes are mechanical. `-Zprint-mono-items=lazy` was removed
without additional changes, and `-Zprint-mono-items=eager` was turned
into `-Clink-dead-code`.  Linking dead code disables internalization, so
tests have been updated accordingly.

Author: tmiasko

compiler/rustc_interface/src/tests.rs

@@ -720,7 +720,7 @@ fn test_unstable_options_tracking_hash() {
     untracked!(pre_link_args, vec![String::from("abc"), String::from("def")]);
     untracked!(print_codegen_stats, true);
     untracked!(print_llvm_passes, true);
-    untracked!(print_mono_items, Some(String::from("abc")));
+    untracked!(print_mono_items, true);
     untracked!(print_type_sizes, true);
     untracked!(proc_macro_backtrace, true);
     untracked!(proc_macro_execution_strategy, ProcMacroExecutionStrategy::CrossThread);

compiler/rustc_monomorphize/messages.ftl

@@ -60,9 +60,6 @@ monomorphize_start_not_found = using `fn main` requires the standard library
 
 monomorphize_symbol_already_defined = symbol `{$symbol}` is already defined
 
-monomorphize_unknown_cgu_collection_mode =
-    unknown codegen-item collection mode '{$mode}', falling back to 'lazy' mode
-
 monomorphize_wasm_c_abi_transition =
     this function {$is_call ->
       [true] call

compiler/rustc_monomorphize/src/errors.rs

@@ -64,12 +64,6 @@ pub(crate) struct EncounteredErrorWhileInstantiating {
 #[help]
 pub(crate) struct StartNotFound;
 
-#[derive(Diagnostic)]
-#[diag(monomorphize_unknown_cgu_collection_mode)]
-pub(crate) struct UnknownCguCollectionMode<'a> {
-    pub mode: &'a str,
-}
-
 #[derive(Diagnostic)]
 #[diag(monomorphize_abi_error_disabled_vector_type)]
 #[help]

compiler/rustc_monomorphize/src/partitioning.rs

@@ -124,7 +124,7 @@ use rustc_target::spec::SymbolVisibility;
 use tracing::debug;
 
 use crate::collector::{self, MonoItemCollectionStrategy, UsageMap};
-use crate::errors::{CouldntDumpMonoStats, SymbolAlreadyDefined, UnknownCguCollectionMode};
+use crate::errors::{CouldntDumpMonoStats, SymbolAlreadyDefined};
 
 struct PartitioningCx<'a, 'tcx> {
     tcx: TyCtxt<'tcx>,
@@ -1127,27 +1127,10 @@ where
 }
 
 fn collect_and_partition_mono_items(tcx: TyCtxt<'_>, (): ()) -> MonoItemPartitions<'_> {
-    let collection_strategy = match tcx.sess.opts.unstable_opts.print_mono_items {
-        Some(ref s) => {
-            let mode = s.to_lowercase();
-            let mode = mode.trim();
-            if mode == "eager" {
-                MonoItemCollectionStrategy::Eager
-            } else {
-                if mode != "lazy" {
-                    tcx.dcx().emit_warn(UnknownCguCollectionMode { mode });
-                }
-
-                MonoItemCollectionStrategy::Lazy
-            }
-        }
-        None => {
-            if tcx.sess.link_dead_code() {
-                MonoItemCollectionStrategy::Eager
-            } else {
-                MonoItemCollectionStrategy::Lazy
-            }
-        }
+    let collection_strategy = if tcx.sess.link_dead_code() {
+        MonoItemCollectionStrategy::Eager
+    } else {
+        MonoItemCollectionStrategy::Lazy
     };
 
     let (items, usage_map) = collector::collect_crate_mono_items(tcx, collection_strategy);
@@ -1209,7 +1192,7 @@ fn collect_and_partition_mono_items(tcx: TyCtxt<'_>, (): ()) -> MonoItemPartitio
         }
     }
 
-    if tcx.sess.opts.unstable_opts.print_mono_items.is_some() {
+    if tcx.sess.opts.unstable_opts.print_mono_items {
         let mut item_to_cgus: UnordMap<_, Vec<_>> = Default::default();
 
         for cgu in codegen_units {

compiler/rustc_session/src/options.rs

@@ -2408,10 +2408,8 @@ options! {
         "print codegen statistics (default: no)"),
     print_llvm_passes: bool = (false, parse_bool, [UNTRACKED],
         "print the LLVM optimization passes being run (default: no)"),
-    print_mono_items: Option<String> = (None, parse_opt_string, [UNTRACKED],
-        "print the result of the monomorphization collection pass. \
-         Value `lazy` means to use normal collection; `eager` means to collect all items.
-         Note that this overwrites the effect `-Clink-dead-code` has on collection!"),
+    print_mono_items: bool = (false, parse_bool, [UNTRACKED],
+        "print the result of the monomorphization collection pass (default: no)"),
     print_type_sizes: bool = (false, parse_bool, [UNTRACKED],
         "print layout information for each type encountered (default: no)"),
     proc_macro_backtrace: bool = (false, parse_bool, [UNTRACKED],

src/doc/rustc-dev-guide/src/tests/compiletest.md

@@ -325,12 +325,8 @@ The tests in [`tests/codegen-units`] test the
 [monomorphization](../backend/monomorph.md) collector and CGU partitioning.
 
 These tests work by running `rustc` with a flag to print the result of the
-monomorphization collection pass, and then special annotations in the file are
-used to compare against that.
-
-Each test should be annotated with the `//@
-compile-flags:-Zprint-mono-items=VAL` directive with the appropriate `VAL` to
-instruct `rustc` to print the monomorphization information.
+monomorphization collection pass, i.e., `-Zprint-mono-items`, and then special
+annotations in the file are used to compare against that.
 
 Then, the test should be annotated with comments of the form `//~ MONO_ITEM
 name` where `name` is the monomorphized string printed by rustc like `fn <u32 as

src/tools/compiletest/src/runtest.rs

@@ -1583,7 +1583,10 @@ impl<'test> TestCx<'test> {
             Crashes => {
                 set_mir_dump_dir(&mut rustc);
             }
-            Pretty | DebugInfo | Rustdoc | RustdocJson | RunMake | CodegenUnits | RustdocJs => {
+            CodegenUnits => {
+                rustc.arg("-Zprint-mono-items");
+            }
+            Pretty | DebugInfo | Rustdoc | RustdocJson | RunMake | RustdocJs => {
                 // do not use JSON output
             }
         }

tests/codegen-units/item-collection/asm-sym.rs

@@ -1,5 +1,5 @@
 //@ needs-asm-support
-//@ compile-flags: -Ccodegen-units=1 -Zprint-mono-items=lazy --crate-type=lib
+//@ compile-flags: -Ccodegen-units=1 --crate-type=lib
 
 #[inline(always)]
 pub unsafe fn f() {

tests/codegen-units/item-collection/closures.rs

@@ -1,5 +1,5 @@
 //@ edition: 2021
-//@ compile-flags: -Zprint-mono-items=eager --crate-type=lib
+//@ compile-flags: -Clink-dead-code --crate-type=lib
 
 //~ MONO_ITEM fn async_fn @@
 //~ MONO_ITEM fn async_fn::{closure#0} @@

tests/codegen-units/item-collection/cross-crate-closures.rs

@@ -1,6 +1,6 @@
 // We need to disable MIR inlining in both this and its aux-build crate. The MIR inliner
 // will just inline everything into our start function if we let it. As it should.
-//@ compile-flags:-Zprint-mono-items=eager -Zinline-mir=no
+//@ compile-flags:-Clink-dead-code -Zinline-mir=no
 
 #![deny(dead_code)]
 #![no_main]
@@ -11,12 +11,12 @@ extern crate cgu_extern_closures;
 //~ MONO_ITEM fn main @@ cross_crate_closures-cgu.0[External]
 #[no_mangle]
 extern "C" fn main(_: core::ffi::c_int, _: *const *const u8) -> core::ffi::c_int {
-    //~ MONO_ITEM fn cgu_extern_closures::inlined_fn @@ cross_crate_closures-cgu.0[Internal]
-    //~ MONO_ITEM fn cgu_extern_closures::inlined_fn::{closure#0} @@ cross_crate_closures-cgu.0[Internal]
+    //~ MONO_ITEM fn cgu_extern_closures::inlined_fn @@ cross_crate_closures-cgu.0[External]
+    //~ MONO_ITEM fn cgu_extern_closures::inlined_fn::{closure#0} @@ cross_crate_closures-cgu.0[External]
     let _ = cgu_extern_closures::inlined_fn(1, 2);
 
-    //~ MONO_ITEM fn cgu_extern_closures::inlined_fn_generic::<i32> @@ cross_crate_closures-cgu.0[Internal]
-    //~ MONO_ITEM fn cgu_extern_closures::inlined_fn_generic::<i32>::{closure#0} @@ cross_crate_closures-cgu.0[Internal]
+    //~ MONO_ITEM fn cgu_extern_closures::inlined_fn_generic::<i32> @@ cross_crate_closures-cgu.0[External]
+    //~ MONO_ITEM fn cgu_extern_closures::inlined_fn_generic::<i32>::{closure#0} @@ cross_crate_closures-cgu.0[External]
     let _ = cgu_extern_closures::inlined_fn_generic(3, 4, 5i32);
 
     // Nothing should be generated for this call, we just link to the instance

tests/codegen-units/item-collection/cross-crate-generic-functions.rs

@@ -1,4 +1,4 @@
-//@ compile-flags:-Zprint-mono-items=eager
+//@ compile-flags:-Clink-dead-code
 
 #![deny(dead_code)]
 #![crate_type = "lib"]

tests/codegen-units/item-collection/cross-crate-trait-method.rs

@@ -1,4 +1,4 @@
-//@ compile-flags:-Zprint-mono-items=eager -Zinline-mir=no -Copt-level=0
+//@ compile-flags:-Clink-dead-code -Zinline-mir=no -Copt-level=0
 
 #![deny(dead_code)]
 #![crate_type = "lib"]

tests/codegen-units/item-collection/drop-glue-eager.rs

@@ -1,6 +1,6 @@
 // Ensure that we *eagerly* monomorphize drop instances for structs with lifetimes.
 
-//@ compile-flags:-Zprint-mono-items=eager
+//@ compile-flags:-Clink-dead-code
 //@ compile-flags:--crate-type=lib
 
 //~ MONO_ITEM fn std::ptr::drop_in_place::<StructWithDrop> - shim(Some(StructWithDrop))

tests/codegen-units/item-collection/drop_in_place_intrinsic.rs

@@ -1,4 +1,4 @@
-//@ compile-flags:-Zprint-mono-items=eager
+//@ compile-flags:-Clink-dead-code
 //@ compile-flags:-Zinline-mir=no
 //@ compile-flags: -O
 

tests/codegen-units/item-collection/function-as-argument.rs

@@ -1,4 +1,4 @@
-//@ compile-flags:-Zprint-mono-items=eager -Zinline-mir=no
+//@ compile-flags:-Clink-dead-code -Zinline-mir=no
 
 #![deny(dead_code)]
 #![crate_type = "lib"]

tests/codegen-units/item-collection/generic-drop-glue.rs

@@ -1,4 +1,4 @@
-//@ compile-flags:-Zprint-mono-items=eager
+//@ compile-flags:-Clink-dead-code
 //@ compile-flags: -O
 
 #![deny(dead_code)]

tests/codegen-units/item-collection/generic-functions.rs

@@ -1,4 +1,4 @@
-//@ compile-flags:-Zprint-mono-items=eager -Zinline-mir=no
+//@ compile-flags:-Clink-dead-code -Zinline-mir=no
 
 #![deny(dead_code)]
 #![crate_type = "lib"]

tests/codegen-units/item-collection/generic-impl.rs

@@ -1,4 +1,4 @@
-//@ compile-flags:-Zprint-mono-items=eager -Zinline-mir=no
+//@ compile-flags:-Clink-dead-code -Zinline-mir=no
 
 #![deny(dead_code)]
 #![crate_type = "lib"]

tests/codegen-units/item-collection/impl-in-non-instantiated-generic.rs

@@ -1,4 +1,4 @@
-//@ compile-flags:-Zprint-mono-items=eager
+//@ compile-flags:-Clink-dead-code
 
 #![deny(dead_code)]
 #![crate_type = "lib"]

tests/codegen-units/item-collection/implicit-panic-call.rs

@@ -1,5 +1,3 @@
-//@ compile-flags:-Zprint-mono-items=lazy
-
 // rust-lang/rust#90405
 // Ensure implicit panic calls are collected
 

tests/codegen-units/item-collection/instantiation-through-vtable.rs

@@ -1,4 +1,4 @@
-//@ compile-flags:-Zprint-mono-items=eager -Zmir-opt-level=0
+//@ compile-flags:-Clink-dead-code -Zmir-opt-level=0
 
 #![deny(dead_code)]
 #![crate_type = "lib"]
@@ -24,15 +24,15 @@ impl<T> Trait for Struct<T> {
 pub fn start(_: isize, _: *const *const u8) -> isize {
     let s1 = Struct { _a: 0u32 };
 
-    //~ MONO_ITEM fn std::ptr::drop_in_place::<Struct<u32>> - shim(None) @@ instantiation_through_vtable-cgu.0[Internal]
+    //~ MONO_ITEM fn std::ptr::drop_in_place::<Struct<u32>> - shim(None) @@ instantiation_through_vtable-cgu.0[External]
     //~ MONO_ITEM fn <Struct<u32> as Trait>::foo
     //~ MONO_ITEM fn <Struct<u32> as Trait>::bar
     let r1 = &s1 as &Trait;
     r1.foo();
     r1.bar();
 
     let s1 = Struct { _a: 0u64 };
-    //~ MONO_ITEM fn std::ptr::drop_in_place::<Struct<u64>> - shim(None) @@ instantiation_through_vtable-cgu.0[Internal]
+    //~ MONO_ITEM fn std::ptr::drop_in_place::<Struct<u64>> - shim(None) @@ instantiation_through_vtable-cgu.0[External]
     //~ MONO_ITEM fn <Struct<u64> as Trait>::foo
     //~ MONO_ITEM fn <Struct<u64> as Trait>::bar
     let _ = &s1 as &Trait;

tests/codegen-units/item-collection/items-within-generic-items.rs

@@ -1,4 +1,4 @@
-//@ compile-flags:-Zprint-mono-items=eager -Copt-level=0
+//@ compile-flags:-Clink-dead-code -Copt-level=0
 
 #![deny(dead_code)]
 #![crate_type = "lib"]

tests/codegen-units/item-collection/non-generic-closures.rs

@@ -1,39 +1,39 @@
-//@ compile-flags:-Zprint-mono-items=eager -Zinline-mir=no
+//@ compile-flags:-Clink-dead-code -Zinline-mir=no
 
 #![deny(dead_code)]
 #![crate_type = "lib"]
 
-//~ MONO_ITEM fn temporary @@ non_generic_closures-cgu.0[Internal]
+//~ MONO_ITEM fn temporary @@ non_generic_closures-cgu.0[External]
 fn temporary() {
-    //~ MONO_ITEM fn temporary::{closure#0} @@ non_generic_closures-cgu.0[Internal]
+    //~ MONO_ITEM fn temporary::{closure#0} @@ non_generic_closures-cgu.0[External]
     (|a: u32| {
         let _ = a;
     })(4);
 }
 
-//~ MONO_ITEM fn assigned_to_variable_but_not_executed @@ non_generic_closures-cgu.0[Internal]
+//~ MONO_ITEM fn assigned_to_variable_but_not_executed @@ non_generic_closures-cgu.0[External]
 fn assigned_to_variable_but_not_executed() {
     //~ MONO_ITEM fn assigned_to_variable_but_not_executed::{closure#0}
     let _x = |a: i16| {
         let _ = a + 1;
     };
 }
 
-//~ MONO_ITEM fn assigned_to_variable_executed_indirectly @@ non_generic_closures-cgu.0[Internal]
+//~ MONO_ITEM fn assigned_to_variable_executed_indirectly @@ non_generic_closures-cgu.0[External]
 fn assigned_to_variable_executed_indirectly() {
-    //~ MONO_ITEM fn assigned_to_variable_executed_indirectly::{closure#0} @@ non_generic_closures-cgu.0[Internal]
-    //~ MONO_ITEM fn <{closure@TEST_PATH:28:13: 28:21} as std::ops::FnOnce<(i32,)>>::call_once - shim @@ non_generic_closures-cgu.0[Internal]
-    //~ MONO_ITEM fn <{closure@TEST_PATH:28:13: 28:21} as std::ops::FnOnce<(i32,)>>::call_once - shim(vtable) @@ non_generic_closures-cgu.0[Internal]
-    //~ MONO_ITEM fn std::ptr::drop_in_place::<{closure@TEST_PATH:28:13: 28:21}> - shim(None) @@ non_generic_closures-cgu.0[Internal]
+    //~ MONO_ITEM fn assigned_to_variable_executed_indirectly::{closure#0} @@ non_generic_closures-cgu.0[External]
+    //~ MONO_ITEM fn <{closure@TEST_PATH:28:13: 28:21} as std::ops::FnOnce<(i32,)>>::call_once - shim @@ non_generic_closures-cgu.0[External]
+    //~ MONO_ITEM fn <{closure@TEST_PATH:28:13: 28:21} as std::ops::FnOnce<(i32,)>>::call_once - shim(vtable) @@ non_generic_closures-cgu.0[External]
+    //~ MONO_ITEM fn std::ptr::drop_in_place::<{closure@TEST_PATH:28:13: 28:21}> - shim(None) @@ non_generic_closures-cgu.0[External]
     let f = |a: i32| {
         let _ = a + 2;
     };
     run_closure(&f);
 }
 
-//~ MONO_ITEM fn assigned_to_variable_executed_directly @@ non_generic_closures-cgu.0[Internal]
+//~ MONO_ITEM fn assigned_to_variable_executed_directly @@ non_generic_closures-cgu.0[External]
 fn assigned_to_variable_executed_directly() {
-    //~ MONO_ITEM fn assigned_to_variable_executed_directly::{closure#0} @@ non_generic_closures-cgu.0[Internal]
+    //~ MONO_ITEM fn assigned_to_variable_executed_directly::{closure#0} @@ non_generic_closures-cgu.0[External]
     let f = |a: i64| {
         let _ = a + 3;
     };
@@ -51,7 +51,7 @@ pub fn start(_: isize, _: *const *const u8) -> isize {
     0
 }
 
-//~ MONO_ITEM fn run_closure @@ non_generic_closures-cgu.0[Internal]
+//~ MONO_ITEM fn run_closure @@ non_generic_closures-cgu.0[External]
 fn run_closure(f: &Fn(i32)) {
     f(3);
 }

tests/codegen-units/item-collection/non-generic-drop-glue.rs

@@ -1,4 +1,4 @@
-//@ compile-flags:-Zprint-mono-items=eager
+//@ compile-flags:-Clink-dead-code
 //@ compile-flags: -O
 
 #![deny(dead_code)]

tests/codegen-units/item-collection/non-generic-functions.rs

@@ -1,4 +1,4 @@
-//@ compile-flags:-Zprint-mono-items=eager
+//@ compile-flags:-Clink-dead-code
 
 #![deny(dead_code)]
 #![crate_type = "lib"]

tests/codegen-units/item-collection/overloaded-operators.rs

@@ -1,4 +1,4 @@
-//@ compile-flags:-Zprint-mono-items=eager
+//@ compile-flags:-Clink-dead-code
 
 #![deny(dead_code)]
 #![crate_type = "lib"]

tests/codegen-units/item-collection/static-init.rs

@@ -1,4 +1,4 @@
-//@ compile-flags:-Zprint-mono-items=eager
+//@ compile-flags:-Clink-dead-code
 
 #![crate_type = "lib"]
 

tests/codegen-units/item-collection/statics-and-consts.rs

@@ -1,4 +1,4 @@
-//@ compile-flags:-Zprint-mono-items=eager
+//@ compile-flags:-Clink-dead-code
 
 #![deny(dead_code)]
 #![crate_type = "lib"]

tests/codegen-units/item-collection/trait-implementations.rs

@@ -1,4 +1,4 @@
-//@ compile-flags:-Zprint-mono-items=eager -Zinline-mir=no
+//@ compile-flags:-Clink-dead-code -Zinline-mir=no
 
 #![deny(dead_code)]
 #![crate_type = "lib"]

tests/codegen-units/item-collection/trait-method-as-argument.rs

@@ -1,4 +1,4 @@
-//@ compile-flags:-Zprint-mono-items=eager -Zinline-mir=no
+//@ compile-flags:-Clink-dead-code -Zinline-mir=no
 
 #![deny(dead_code)]
 #![crate_type = "lib"]

tests/codegen-units/item-collection/trait-method-default-impl.rs

@@ -1,4 +1,4 @@
-//@ compile-flags:-Zprint-mono-items=eager -Zinline-mir=no
+//@ compile-flags:-Clink-dead-code -Zinline-mir=no
 
 #![deny(dead_code)]
 #![crate_type = "lib"]

tests/codegen-units/item-collection/transitive-drop-glue.rs

@@ -1,4 +1,4 @@
-//@ compile-flags:-Zprint-mono-items=eager
+//@ compile-flags:-Clink-dead-code
 //@ compile-flags: -O
 
 #![deny(dead_code)]

tests/codegen-units/item-collection/tuple-drop-glue.rs

@@ -1,4 +1,4 @@
-//@ compile-flags:-Zprint-mono-items=eager
+//@ compile-flags:-Clink-dead-code
 //@ compile-flags: -O
 
 #![deny(dead_code)]

tests/codegen-units/item-collection/unreferenced-const-fn.rs

@@ -1,5 +1,3 @@
-//@ compile-flags:-Zprint-mono-items=lazy
-
 #![deny(dead_code)]
 #![crate_type = "rlib"]
 

tests/codegen-units/item-collection/unreferenced-inline-function.rs

@@ -1,5 +1,3 @@
-//@ compile-flags:-Zprint-mono-items=lazy
-
 // N.B., we do not expect *any* monomorphization to be generated here.
 
 #![deny(dead_code)]

tests/codegen-units/item-collection/unsizing.rs

@@ -1,4 +1,3 @@
-//@ compile-flags:-Zprint-mono-items=eager
 //@ compile-flags:-Zmir-opt-level=0
 
 #![deny(dead_code)]

tests/codegen-units/item-collection/unused-traits-and-generics.rs

@@ -1,4 +1,4 @@
-//@ compile-flags:-Zprint-mono-items=eager
+//@ compile-flags:-Clink-dead-code
 
 #![crate_type = "lib"]
 #![deny(dead_code)]