Rollup merge of #75675 - davidtwco:symbol-mangling-impl-params, r=eddyb

mangling: mangle impl params w/ v0 scheme This PR modifies v0 symbol mangling to include all generic parameters from impl blocks (not just those used in the self type) - an alternative fix to #75326. ``` original: _RNCNvXCs4fqI2P2rA04_19impl_param_manglingINtB4_3FooppENtNtNtNtCsfnEnqCNU58Z_4core4iter6traits8iterator8Iterator4next0B4_ // |------------ B4_ ----------------| // _R (N C (N v (X (C ((s 4fqI2p2rA04_) 19impl_param_mangling)) (I (N t B4_ 3Foo) pp E) (N t (N t (N t (N t (C ((s fnEnqCNU58Z_) 4core)) 4iter) 6traits) 8iterator) 8Iterator)) 4next) 0) B4_ modified: _RNvXINICs4fqI2P2rA04_11issue_753260pppEINtB5_3FooppENtNtNtNtCsfnEnqCNU58Z_4core4iter6traits8iterator8Iterator4nextB5_ // _R (N v (X (I (N I (C ((s 4fqI2P2rA04_) 11issue_75326)) 0) ppp E) (I (N t B5_ 3Foo) pp E) (N t (N t (N t (N t (C ((s fnEnqCNU58Z_) 4core)) 4iter) 6traits) 8iterator) 8Iterator)) 4next) B5_ // | ^ | // | | | // | new impl namespace | ``` ~~Submitted as a draft as after some discussion w/ @eddyb, I'm going to do some investigation into (yet more alternative) changes to polymorphization that might remove the necessity for this.~~ r? @eddyb
2024-12-23 22:14:15 +00:00 · 2020-10-16 02:10:02 +02:00 · 2020-10-16 02:10:02 +02:00 · 1643fd86a7
commit 1643fd86a7
parent 977df43c4a fbdfe2c63b
8 changed files with 159 additions and 44 deletions
--- a/compiler/rustc_middle/src/ty/instance.rs
+++ b/compiler/rustc_middle/src/ty/instance.rs
@ -291,7 +291,17 @@ impl<'tcx> Instance<'tcx> {
    }

    pub fn mono(tcx: TyCtxt<'tcx>, def_id: DefId) -> Instance<'tcx> {
-        Instance::new(def_id, tcx.empty_substs_for_def_id(def_id))
+        let substs = InternalSubsts::for_item(tcx, def_id, |param, _| match param.kind {
+            ty::GenericParamDefKind::Lifetime => tcx.lifetimes.re_erased.into(),
+            ty::GenericParamDefKind::Type { .. } => {
+                bug!("Instance::mono: {:?} has type parameters", def_id)
+            }
+            ty::GenericParamDefKind::Const { .. } => {
+                bug!("Instance::mono: {:?} has const parameters", def_id)
+            }
+        });
+
+        Instance::new(def_id, substs)
    }

    #[inline]
--- a/compiler/rustc_middle/src/ty/util.rs
+++ b/compiler/rustc_middle/src/ty/util.rs
@ -6,9 +6,9 @@ use crate::mir::interpret::{sign_extend, truncate};
 use crate::ty::fold::TypeFolder;
 use crate::ty::layout::IntegerExt;
 use crate::ty::query::TyCtxtAt;
-use crate::ty::subst::{GenericArgKind, InternalSubsts, Subst, SubstsRef};
+use crate::ty::subst::{GenericArgKind, Subst, SubstsRef};
 use crate::ty::TyKind::*;
-use crate::ty::{self, DefIdTree, GenericParamDefKind, List, Ty, TyCtxt, TypeFoldable};
+use crate::ty::{self, DefIdTree, List, Ty, TyCtxt, TypeFoldable};
 use rustc_apfloat::Float as _;
 use rustc_ast as ast;
 use rustc_attr::{self as attr, SignedInt, UnsignedInt};
@ -509,20 +509,6 @@ impl<'tcx> TyCtxt<'tcx> {
        Some(ty::Binder::bind(env_ty))
    }

-    /// Given the `DefId` of some item that has no type or const parameters, make
-    /// a suitable "empty substs" for it.
-    pub fn empty_substs_for_def_id(self, item_def_id: DefId) -> SubstsRef<'tcx> {
-        InternalSubsts::for_item(self, item_def_id, |param, _| match param.kind {
-            GenericParamDefKind::Lifetime => self.lifetimes.re_erased.into(),
-            GenericParamDefKind::Type { .. } => {
-                bug!("empty_substs_for_def_id: {:?} has type parameters", item_def_id)
-            }
-            GenericParamDefKind::Const { .. } => {
-                bug!("empty_substs_for_def_id: {:?} has const parameters", item_def_id)
-            }
-        })
-    }
-
    /// Returns `true` if the node pointed to by `def_id` is a `static` item.
    pub fn is_static(self, def_id: DefId) -> bool {
        self.static_mutability(def_id).is_some()
--- a/compiler/rustc_symbol_mangling/src/legacy.rs
+++ b/compiler/rustc_symbol_mangling/src/legacy.rs
@ -115,7 +115,6 @@ fn get_symbol_hash<'tcx>(
        }

        // also include any type parameters (for generic items)
-        assert!(!substs.has_erasable_regions());
        substs.hash_stable(&mut hcx, &mut hasher);

        if let Some(instantiating_crate) = instantiating_crate {
--- a/compiler/rustc_symbol_mangling/src/test.rs
+++ b/compiler/rustc_symbol_mangling/src/test.rs
@ -6,7 +6,7 @@

 use rustc_hir as hir;
 use rustc_middle::ty::print::with_no_trimmed_paths;
-use rustc_middle::ty::{Instance, TyCtxt};
+use rustc_middle::ty::{subst::InternalSubsts, Instance, TyCtxt};
 use rustc_span::symbol::{sym, Symbol};

 const SYMBOL_NAME: Symbol = sym::rustc_symbol_name;
@ -36,8 +36,11 @@ impl SymbolNamesTest<'tcx> {
        let def_id = tcx.hir().local_def_id(hir_id);
        for attr in tcx.get_attrs(def_id.to_def_id()).iter() {
            if tcx.sess.check_name(attr, SYMBOL_NAME) {
-                // for now, can only use on monomorphic names
-                let instance = Instance::mono(tcx, def_id.to_def_id());
+                let def_id = def_id.to_def_id();
+                let instance = Instance::new(
+                    def_id,
+                    tcx.erase_regions(&InternalSubsts::identity_for_item(tcx, def_id)),
+                );
                let mangled = tcx.symbol_name(instance);
                tcx.sess.span_err(attr.span, &format!("symbol-name({})", mangled));
                if let Ok(demangling) = rustc_demangle::try_demangle(mangled.name) {
--- a/compiler/rustc_symbol_mangling/src/v0.rs
+++ b/compiler/rustc_symbol_mangling/src/v0.rs
@ -259,7 +259,7 @@ impl Printer<'tcx> for SymbolMangler<'tcx> {
    }

    fn print_impl_path(
-        self,
+        mut self,
        impl_def_id: DefId,
        substs: &'tcx [GenericArg<'tcx>],
        mut self_ty: Ty<'tcx>,
@ -284,12 +284,37 @@ impl Printer<'tcx> for SymbolMangler<'tcx> {
            }
        }

-        self.path_append_impl(
+        self.push(match impl_trait_ref {
+            Some(_) => "X",
+            None => "M",
+        });
+
+        // Encode impl generic params if the substitutions contain parameters (implying
+        // polymorphization is enabled) and this isn't an inherent impl.
+        if impl_trait_ref.is_some() && substs.iter().any(|a| a.has_param_types_or_consts()) {
+            self = self.path_generic_args(
+                |this| {
+                    this.path_append_ns(
                        |cx| cx.print_def_path(parent_def_id, &[]),
-            &key.disambiguated_data,
-            self_ty,
-            impl_trait_ref,
+                        'I',
+                        key.disambiguated_data.disambiguator as u64,
+                        "",
                    )
+                },
+                substs,
+            )?;
+        } else {
+            self.push_disambiguator(key.disambiguated_data.disambiguator as u64);
+            self = self.print_def_path(parent_def_id, &[])?;
+        }
+
+        self = self_ty.print(self)?;
+
+        if let Some(trait_ref) = impl_trait_ref {
+            self = self.print_def_path(trait_ref.def_id, trait_ref.substs)?;
+        }
+
+        Ok(self)
    }

    fn print_region(mut self, region: ty::Region<'_>) -> Result<Self::Region, Self::Error> {
@ -538,6 +563,7 @@ impl Printer<'tcx> for SymbolMangler<'tcx> {
        self.push_ident(&name);
        Ok(self)
    }
+
    fn path_qualified(
        mut self,
        self_ty: Ty<'tcx>,
@ -552,24 +578,16 @@ impl Printer<'tcx> for SymbolMangler<'tcx> {
    }

    fn path_append_impl(
-        mut self,
-        print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
-        disambiguated_data: &DisambiguatedDefPathData,
-        self_ty: Ty<'tcx>,
-        trait_ref: Option<ty::TraitRef<'tcx>>,
+        self,
+        _: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
+        _: &DisambiguatedDefPathData,
+        _: Ty<'tcx>,
+        _: Option<ty::TraitRef<'tcx>>,
    ) -> Result<Self::Path, Self::Error> {
-        self.push(match trait_ref {
-            Some(_) => "X",
-            None => "M",
-        });
-        self.push_disambiguator(disambiguated_data.disambiguator as u64);
-        self = print_prefix(self)?;
-        self = self_ty.print(self)?;
-        if let Some(trait_ref) = trait_ref {
-            self = self.print_def_path(trait_ref.def_id, trait_ref.substs)?;
-        }
-        Ok(self)
+        // Inlined into `print_impl_path`
+        unreachable!()
    }
+
    fn path_append(
        self,
        print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
@ -603,6 +621,7 @@ impl Printer<'tcx> for SymbolMangler<'tcx> {
            name.as_ref().map_or("", |s| &s[..]),
        )
    }
+
    fn path_generic_args(
        mut self,
        print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
--- a/src/test/ui/symbol-names/issue-75326.legacy.stderr
+++ b/src/test/ui/symbol-names/issue-75326.legacy.stderr
@ -0,0 +1,20 @@
+error: symbol-name(_ZN72_$LT$issue_75326..Foo$LT$I$C$E$GT$$u20$as$u20$issue_75326..Iterator2$GT$4next17SYMBOL_HASH)
+  --> $DIR/issue-75326.rs:43:5
+   |
+LL |     #[rustc_symbol_name]
+   |     ^^^^^^^^^^^^^^^^^^^^
+
+error: demangling(<issue_75326::Foo<I,E> as issue_75326::Iterator2>::next::SYMBOL_HASH)
+  --> $DIR/issue-75326.rs:43:5
+   |
+LL |     #[rustc_symbol_name]
+   |     ^^^^^^^^^^^^^^^^^^^^
+
+error: demangling-alt(<issue_75326::Foo<I,E> as issue_75326::Iterator2>::next)
+  --> $DIR/issue-75326.rs:43:5
+   |
+LL |     #[rustc_symbol_name]
+   |     ^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 3 previous errors
+
--- a/src/test/ui/symbol-names/issue-75326.rs
+++ b/src/test/ui/symbol-names/issue-75326.rs
@ -0,0 +1,58 @@
+// build-fail
+// ignore-tidy-linelength
+// revisions: legacy v0
+//[legacy]compile-flags: -Z symbol-mangling-version=legacy
+//[v0]compile-flags: -Z symbol-mangling-version=v0
+//[legacy]normalize-stderr-32bit: "h[\d\w]+" -> "SYMBOL_HASH"
+//[legacy]normalize-stderr-64bit: "h[\d\w]+" -> "SYMBOL_HASH"
+
+#![feature(rustc_attrs)]
+
+pub(crate) struct Foo<I, E>(I, E);
+
+pub trait Iterator2 {
+    type Item;
+
+    fn next(&mut self) -> Option<Self::Item>;
+
+    fn find<P>(&mut self, predicate: P) -> Option<Self::Item>
+    where
+        Self: Sized,
+        P: FnMut(&Self::Item) -> bool,
+    {
+        unimplemented!()
+    }
+}
+
+struct Bar;
+
+impl Iterator2 for Bar {
+    type Item = (u32, u16);
+
+    fn next(&mut self) -> Option<Self::Item> {
+        unimplemented!()
+    }
+}
+
+impl<I, T, E> Iterator2 for Foo<I, E>
+where
+    I: Iterator2<Item = (T, E)>,
+{
+    type Item = T;
+
+    #[rustc_symbol_name]
+    //[legacy]~^ ERROR symbol-name(_ZN72_$LT$issue_75326..Foo$LT$I$C$E$GT$$u20$as$u20$issue_75326..Iterator2$GT$4next
+    //[legacy]~| ERROR demangling(<issue_75326::Foo<I,E> as issue_75326::Iterator2>::next
+    //[legacy]~| ERROR demangling-alt(<issue_75326::Foo<I,E> as issue_75326::Iterator2>::next)
+    //[v0]~^^^^  ERROR symbol-name(_RNvXINICs4fqI2P2rA04_11issue_75326s_0pppEINtB5_3FooppENtB5_9Iterator24nextB5_)
+    //[v0]~|     ERROR demangling(<issue_75326[317d481089b8c8fe]::Foo<_, _> as issue_75326[317d481089b8c8fe]::Iterator2>::next)
+    //[v0]~|     ERROR demangling-alt(<issue_75326::Foo<_, _> as issue_75326::Iterator2>::next)
+    fn next(&mut self) -> Option<Self::Item> {
+        self.find(|_| true)
+    }
+}
+
+fn main() {
+    let mut a = Foo(Bar, 1u16);
+    let _ = a.next();
+}
--- a/src/test/ui/symbol-names/issue-75326.v0.stderr
+++ b/src/test/ui/symbol-names/issue-75326.v0.stderr
@ -0,0 +1,20 @@
+error: symbol-name(_RNvXINICs4fqI2P2rA04_11issue_75326s_0pppEINtB5_3FooppENtB5_9Iterator24nextB5_)
+  --> $DIR/issue-75326.rs:43:5
+   |
+LL |     #[rustc_symbol_name]
+   |     ^^^^^^^^^^^^^^^^^^^^
+
+error: demangling(<issue_75326[317d481089b8c8fe]::Foo<_, _> as issue_75326[317d481089b8c8fe]::Iterator2>::next)
+  --> $DIR/issue-75326.rs:43:5
+   |
+LL |     #[rustc_symbol_name]
+   |     ^^^^^^^^^^^^^^^^^^^^
+
+error: demangling-alt(<issue_75326::Foo<_, _> as issue_75326::Iterator2>::next)
+  --> $DIR/issue-75326.rs:43:5
+   |
+LL |     #[rustc_symbol_name]
+   |     ^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 3 previous errors
+