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Remove (useless) argument of entry_fn query #71648

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Remove (useless) argument of entry_fn query #71648

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4 changes: 2 additions & 2 deletions src/librustc_codegen_llvm/debuginfo/mod.rs
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Expand Up @@ -22,7 +22,7 @@ use rustc_codegen_ssa::debuginfo::type_names;
use rustc_codegen_ssa::mir::debuginfo::{DebugScope, FunctionDebugContext, VariableKind};
use rustc_codegen_ssa::traits::*;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LOCAL_CRATE};
use rustc_hir::def_id::{CrateNum, DefId, DefIdMap};
use rustc_index::vec::IndexVec;
use rustc_middle::mir;
use rustc_middle::ty::layout::HasTyCtxt;
Expand Down Expand Up @@ -289,7 +289,7 @@ impl DebugInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> {
if self.sess().opts.optimize != config::OptLevel::No {
spflags |= DISPFlags::SPFlagOptimized;
}
if let Some((id, _)) = self.tcx.entry_fn(LOCAL_CRATE) {
if let Some((id, _)) = self.tcx.entry_fn(()) {
if id.to_def_id() == def_id {
spflags |= DISPFlags::SPFlagMainSubprogram;
}
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2 changes: 1 addition & 1 deletion src/librustc_codegen_ssa/back/symbol_export.rs
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Expand Up @@ -178,7 +178,7 @@ fn exported_symbols_provider_local(
.map(|(&def_id, &level)| (ExportedSymbol::NonGeneric(def_id), level))
.collect();

if tcx.entry_fn(LOCAL_CRATE).is_some() {
if tcx.entry_fn(()).is_some() {
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Can we give a name (LocalCrate) to the unit struct that implements query::Key? Otherwise, it's not immediately clear to me what this line is doing.

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That seems like a good idea to me. @eddyb do you agree?

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That's one way. But this is basically a nulary query.
If we tweaked the macros a bit we could write this instead:

if tcx.entry_fn().is_some() {

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If we go that route, we should rename the entry_fn query to entry_fn_local_crate. Otherwise the same readability issues apply.

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I wonder if adding an improved doc comment would suffice? It seems reasonable clear to me that the entry_fn computes, well, the entry function -- I guess the thing that is sort of non-obvious is the overall model where the root crate has an entry function, and it seems like that would be best explained in docs?

In particular, entry_fn_for_local_crate (if we're going to use a long name, I'd prefer to make it read well...) seems to imply that other crates can have entry functions, which isn't really true?

Anyway, a minor thing, but I guess it may become a more wide-spread convention either way.

let exported_symbol = ExportedSymbol::NoDefId(SymbolName::new("main"));

symbols.push((exported_symbol, SymbolExportLevel::C));
Expand Down
4 changes: 2 additions & 2 deletions src/librustc_codegen_ssa/base.rs
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Expand Up @@ -392,7 +392,7 @@ pub fn codegen_instance<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>>(
pub fn maybe_create_entry_wrapper<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
cx: &'a Bx::CodegenCx,
) -> Option<Bx::Function> {
let (main_def_id, span) = match cx.tcx().entry_fn(LOCAL_CRATE) {
let (main_def_id, span) = match cx.tcx().entry_fn(()) {
Some((def_id, _)) => (def_id, cx.tcx().def_span(def_id)),
None => return None,
};
Expand All @@ -407,7 +407,7 @@ pub fn maybe_create_entry_wrapper<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(

let main_llfn = cx.get_fn_addr(instance);

return cx.tcx().entry_fn(LOCAL_CRATE).map(|(_, et)| {
return cx.tcx().entry_fn(()).map(|(_, et)| {
let use_start_lang_item = EntryFnType::Start != et;
create_entry_fn::<Bx>(cx, span, main_llfn, main_def_id, use_start_lang_item)
});
Expand Down
3 changes: 1 addition & 2 deletions src/librustc_interface/passes.rs
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Expand Up @@ -784,8 +784,7 @@ fn analysis(tcx: TyCtxt<'_>, cnum: CrateNum) -> Result<()> {
sess.time("misc_checking_1", || {
parallel!(
{
entry_point = sess
.time("looking_for_entry_point", || rustc_passes::entry::find_entry_point(tcx));
entry_point = sess.time("looking_for_entry_point", || tcx.entry_fn(()));

sess.time("looking_for_plugin_registrar", || {
plugin::build::find_plugin_registrar(tcx)
Expand Down
2 changes: 1 addition & 1 deletion src/librustc_interface/queries.rs
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Expand Up @@ -288,7 +288,7 @@ impl<'tcx> Queries<'tcx> {
/// to write compile-fail tests that actually test that compilation succeeds without reporting
/// an error.
fn check_for_rustc_errors_attr(tcx: TyCtxt<'_>) {
let def_id = match tcx.entry_fn(LOCAL_CRATE) {
let def_id = match tcx.entry_fn(()) {
Some((def_id, _)) => def_id,
_ => return,
};
Expand Down
2 changes: 1 addition & 1 deletion src/librustc_middle/mir/mono.rs
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Expand Up @@ -90,7 +90,7 @@ impl<'tcx> MonoItem<'tcx> {

match *self {
MonoItem::Fn(ref instance) => {
let entry_def_id = tcx.entry_fn(LOCAL_CRATE).map(|(id, _)| id);
let entry_def_id = tcx.entry_fn(()).map(|(id, _)| id);
// If this function isn't inlined or otherwise has explicit
// linkage, then we'll be creating a globally shared version.
if self.explicit_linkage(tcx).is_some()
Expand Down
4 changes: 2 additions & 2 deletions src/librustc_middle/query/mod.rs
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Expand Up @@ -884,9 +884,9 @@ rustc_queries! {
desc { "looking up the foreign modules of a linked crate" }
}

/// Identifies the entry-point (e.g., the `main` function) for a given
/// Identifies the entry-point (e.g., the `main` function) for the current
/// crate, returning `None` if there is no entry point (such as for library crates).
query entry_fn(_: CrateNum) -> Option<(LocalDefId, EntryFnType)> {
query entry_fn(_: ()) -> Option<(LocalDefId, EntryFnType)> {
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Won't this query only get executed once in the entire dependency tree? So if a lib crate calls the query, you get None and then all other crates just yield that None?

desc { "looking up the entry function of a crate" }
}
query plugin_registrar_fn(_: CrateNum) -> Option<DefId> {
Expand Down
14 changes: 13 additions & 1 deletion src/librustc_middle/ty/query/keys.rs
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Expand Up @@ -6,7 +6,7 @@ use crate::traits;
use crate::ty::fast_reject::SimplifiedType;
use crate::ty::subst::{GenericArg, SubstsRef};
use crate::ty::{self, Ty, TyCtxt};
use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, LOCAL_CRATE};
use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, CRATE_DEF_INDEX, LOCAL_CRATE};
use rustc_query_system::query::DefaultCacheSelector;
use rustc_span::symbol::Symbol;
use rustc_span::{Span, DUMMY_SP};
Expand All @@ -25,6 +25,18 @@ pub trait Key {
fn default_span(&self, tcx: TyCtxt<'_>) -> Span;
}

impl Key for () {
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Wait, this is new? I thought there was precedent for this. I guess we can still go ahead with this.

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I checked, no query have () as argument/key type yet, i think.

type CacheSelector = DefaultCacheSelector;

fn query_crate(&self) -> CrateNum {
LOCAL_CRATE
}

fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
tcx.def_span(DefId::local(CRATE_DEF_INDEX))
}
}

impl<'tcx> Key for ty::InstanceDef<'tcx> {
type CacheSelector = DefaultCacheSelector;

Expand Down
4 changes: 2 additions & 2 deletions src/librustc_mir/monomorphize/collector.rs
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Expand Up @@ -180,7 +180,7 @@ use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_data_structures::sync::{par_iter, MTLock, MTRef, ParallelIterator};
use rustc_errors::ErrorReported;
use rustc_hir as hir;
use rustc_hir::def_id::{DefId, DefIdMap, LocalDefId, LOCAL_CRATE};
use rustc_hir::def_id::{DefId, DefIdMap, LocalDefId};
use rustc_hir::itemlikevisit::ItemLikeVisitor;
use rustc_hir::lang_items::{ExchangeMallocFnLangItem, StartFnLangItem};
use rustc_index::bit_set::GrowableBitSet;
Expand Down Expand Up @@ -309,7 +309,7 @@ fn collect_roots(tcx: TyCtxt<'_>, mode: MonoItemCollectionMode) -> Vec<MonoItem<
let mut roots = Vec::new();

{
let entry_fn = tcx.entry_fn(LOCAL_CRATE);
let entry_fn = tcx.entry_fn(());

debug!("collect_roots: entry_fn = {:?}", entry_fn);

Expand Down
2 changes: 1 addition & 1 deletion src/librustc_passes/dead.rs
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Expand Up @@ -452,7 +452,7 @@ fn create_and_seed_worklist<'tcx>(
)
.chain(
// Seed entry point
tcx.entry_fn(LOCAL_CRATE).map(|(def_id, _)| tcx.hir().as_local_hir_id(def_id)),
tcx.entry_fn(()).map(|(def_id, _)| tcx.hir().as_local_hir_id(def_id)),
)
.collect::<Vec<_>>();

Expand Down
10 changes: 2 additions & 8 deletions src/librustc_passes/entry.rs
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@@ -1,7 +1,7 @@
use rustc_ast::attr;
use rustc_ast::entry::EntryPointType;
use rustc_errors::struct_span_err;
use rustc_hir::def_id::{CrateNum, LocalDefId, CRATE_DEF_INDEX, LOCAL_CRATE};
use rustc_hir::def_id::{LocalDefId, CRATE_DEF_INDEX, LOCAL_CRATE};
use rustc_hir::itemlikevisit::ItemLikeVisitor;
use rustc_hir::{HirId, ImplItem, Item, ItemKind, TraitItem};
use rustc_middle::hir::map::Map;
Expand Down Expand Up @@ -48,9 +48,7 @@ impl<'a, 'tcx> ItemLikeVisitor<'tcx> for EntryContext<'a, 'tcx> {
}
}

fn entry_fn(tcx: TyCtxt<'_>, cnum: CrateNum) -> Option<(LocalDefId, EntryFnType)> {
assert_eq!(cnum, LOCAL_CRATE);

fn entry_fn(tcx: TyCtxt<'_>, _: ()) -> Option<(LocalDefId, EntryFnType)> {
let any_exe =
tcx.sess.crate_types.borrow().iter().any(|ty| *ty == config::CrateType::Executable);
if !any_exe {
Expand Down Expand Up @@ -214,10 +212,6 @@ fn no_main_err(tcx: TyCtxt<'_>, visitor: &EntryContext<'_, '_>) {
err.emit();
}

pub fn find_entry_point(tcx: TyCtxt<'_>) -> Option<(LocalDefId, EntryFnType)> {
tcx.entry_fn(LOCAL_CRATE)
}

pub fn provide(providers: &mut Providers<'_>) {
*providers = Providers { entry_fn, ..*providers };
}
2 changes: 1 addition & 1 deletion src/librustc_typeck/check/mod.rs
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Expand Up @@ -1450,7 +1450,7 @@ fn check_fn<'a, 'tcx>(

// Check that the main return type implements the termination trait.
if let Some(term_id) = tcx.lang_items().termination() {
if let Some((def_id, EntryFnType::Main)) = tcx.entry_fn(LOCAL_CRATE) {
if let Some((def_id, EntryFnType::Main)) = tcx.entry_fn(()) {
let main_id = hir.as_local_hir_id(def_id);
if main_id == fn_id {
let substs = tcx.mk_substs_trait(declared_ret_ty, &[]);
Expand Down
2 changes: 1 addition & 1 deletion src/librustc_typeck/lib.rs
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Expand Up @@ -302,7 +302,7 @@ fn check_start_fn_ty(tcx: TyCtxt<'_>, start_def_id: LocalDefId) {
}

fn check_for_entry_fn(tcx: TyCtxt<'_>) {
match tcx.entry_fn(LOCAL_CRATE) {
match tcx.entry_fn(()) {
Some((def_id, EntryFnType::Main)) => check_main_fn_ty(tcx, def_id),
Some((def_id, EntryFnType::Start)) => check_start_fn_ty(tcx, def_id),
_ => {}
Expand Down