Auto merge of rust-lang#6091 - ebroto:rustup, r=ebroto

Rustup

changelog: none

r? `@ghost`

Author: bors

clippy_lints/src/lib.rs

@@ -6,6 +6,7 @@
 #![feature(concat_idents)]
 #![feature(crate_visibility_modifier)]
 #![feature(drain_filter)]
+#![feature(in_band_lifetimes)]
 #![feature(or_patterns)]
 #![feature(rustc_private)]
 #![feature(stmt_expr_attributes)]

clippy_lints/src/missing_const_for_fn.rs

@@ -1,10 +1,10 @@
+use crate::utils::qualify_min_const_fn::is_min_const_fn;
 use crate::utils::{fn_has_unsatisfiable_preds, has_drop, is_entrypoint_fn, span_lint, trait_ref_of_method};
 use rustc_hir as hir;
 use rustc_hir::intravisit::FnKind;
 use rustc_hir::{Body, Constness, FnDecl, GenericParamKind, HirId};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::lint::in_external_macro;
-use rustc_mir::transform::qualify_min_const_fn::is_min_const_fn;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::Span;
 use rustc_typeck::hir_ty_to_ty;

clippy_lints/src/redundant_clone.rs

@@ -87,6 +87,7 @@ impl<'tcx> LateLintPass<'tcx> for RedundantClone {
 
         let maybe_storage_live_result = MaybeStorageLive
             .into_engine(cx.tcx, mir, def_id.to_def_id())
+            .pass_name("redundant_clone")
             .iterate_to_fixpoint()
             .into_results_cursor(mir);
         let mut possible_borrower = {

clippy_lints/src/utils/mod.rs

@@ -18,6 +18,7 @@ pub mod internal_lints;
 pub mod numeric_literal;
 pub mod paths;
 pub mod ptr;
+pub mod qualify_min_const_fn;
 pub mod sugg;
 pub mod usage;
 

clippy_lints/src/utils/qualify_min_const_fn.rs

@@ -0,0 +1,347 @@
+use rustc_hir as hir;
+use rustc_hir::def_id::DefId;
+use rustc_middle::mir::{
+    Body, CastKind, NullOp, Operand, Place, ProjectionElem, Rvalue, Statement, StatementKind, Terminator,
+    TerminatorKind,
+};
+use rustc_middle::ty::subst::GenericArgKind;
+use rustc_middle::ty::{self, adjustment::PointerCast, Ty, TyCtxt};
+use rustc_span::symbol::sym;
+use rustc_span::Span;
+use rustc_target::spec::abi::Abi::RustIntrinsic;
+use std::borrow::Cow;
+
+type McfResult = Result<(), (Span, Cow<'static, str>)>;
+
+pub fn is_min_const_fn(tcx: TyCtxt<'tcx>, def_id: DefId, body: &'a Body<'tcx>) -> McfResult {
+    let mut current = def_id;
+    loop {
+        let predicates = tcx.predicates_of(current);
+        for (predicate, _) in predicates.predicates {
+            match predicate.skip_binders() {
+                ty::PredicateAtom::RegionOutlives(_)
+                | ty::PredicateAtom::TypeOutlives(_)
+                | ty::PredicateAtom::WellFormed(_)
+                | ty::PredicateAtom::Projection(_)
+                | ty::PredicateAtom::ConstEvaluatable(..)
+                | ty::PredicateAtom::ConstEquate(..)
+                | ty::PredicateAtom::TypeWellFormedFromEnv(..) => continue,
+                ty::PredicateAtom::ObjectSafe(_) => panic!("object safe predicate on function: {:#?}", predicate),
+                ty::PredicateAtom::ClosureKind(..) => panic!("closure kind predicate on function: {:#?}", predicate),
+                ty::PredicateAtom::Subtype(_) => panic!("subtype predicate on function: {:#?}", predicate),
+                ty::PredicateAtom::Trait(pred, _) => {
+                    if Some(pred.def_id()) == tcx.lang_items().sized_trait() {
+                        continue;
+                    }
+                    match pred.self_ty().kind() {
+                        ty::Param(ref p) => {
+                            let generics = tcx.generics_of(current);
+                            let def = generics.type_param(p, tcx);
+                            let span = tcx.def_span(def.def_id);
+                            return Err((
+                                span,
+                                "trait bounds other than `Sized` \
+                                 on const fn parameters are unstable"
+                                    .into(),
+                            ));
+                        },
+                        // other kinds of bounds are either tautologies
+                        // or cause errors in other passes
+                        _ => continue,
+                    }
+                },
+            }
+        }
+        match predicates.parent {
+            Some(parent) => current = parent,
+            None => break,
+        }
+    }
+
+    for local in &body.local_decls {
+        check_ty(tcx, local.ty, local.source_info.span)?;
+    }
+    // impl trait is gone in MIR, so check the return type manually
+    check_ty(
+        tcx,
+        tcx.fn_sig(def_id).output().skip_binder(),
+        body.local_decls.iter().next().unwrap().source_info.span,
+    )?;
+
+    for bb in body.basic_blocks() {
+        check_terminator(tcx, body, bb.terminator())?;
+        for stmt in &bb.statements {
+            check_statement(tcx, body, def_id, stmt)?;
+        }
+    }
+    Ok(())
+}
+
+fn check_ty(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, span: Span) -> McfResult {
+    for arg in ty.walk() {
+        let ty = match arg.unpack() {
+            GenericArgKind::Type(ty) => ty,
+
+            // No constraints on lifetimes or constants, except potentially
+            // constants' types, but `walk` will get to them as well.
+            GenericArgKind::Lifetime(_) | GenericArgKind::Const(_) => continue,
+        };
+
+        match ty.kind() {
+            ty::Ref(_, _, hir::Mutability::Mut) => {
+                return Err((span, "mutable references in const fn are unstable".into()));
+            },
+            ty::Opaque(..) => return Err((span, "`impl Trait` in const fn is unstable".into())),
+            ty::FnPtr(..) => {
+                return Err((span, "function pointers in const fn are unstable".into()));
+            },
+            ty::Dynamic(preds, _) => {
+                for pred in preds.iter() {
+                    match pred.skip_binder() {
+                        ty::ExistentialPredicate::AutoTrait(_) | ty::ExistentialPredicate::Projection(_) => {
+                            return Err((
+                                span,
+                                "trait bounds other than `Sized` \
+                                 on const fn parameters are unstable"
+                                    .into(),
+                            ));
+                        },
+                        ty::ExistentialPredicate::Trait(trait_ref) => {
+                            if Some(trait_ref.def_id) != tcx.lang_items().sized_trait() {
+                                return Err((
+                                    span,
+                                    "trait bounds other than `Sized` \
+                                     on const fn parameters are unstable"
+                                        .into(),
+                                ));
+                            }
+                        },
+                    }
+                }
+            },
+            _ => {},
+        }
+    }
+    Ok(())
+}
+
+fn check_rvalue(tcx: TyCtxt<'tcx>, body: &Body<'tcx>, def_id: DefId, rvalue: &Rvalue<'tcx>, span: Span) -> McfResult {
+    match rvalue {
+        Rvalue::ThreadLocalRef(_) => Err((span, "cannot access thread local storage in const fn".into())),
+        Rvalue::Repeat(operand, _) | Rvalue::Use(operand) => check_operand(tcx, operand, span, body),
+        Rvalue::Len(place) | Rvalue::Discriminant(place) | Rvalue::Ref(_, _, place) | Rvalue::AddressOf(_, place) => {
+            check_place(tcx, *place, span, body)
+        },
+        Rvalue::Cast(CastKind::Misc, operand, cast_ty) => {
+            use rustc_middle::ty::cast::CastTy;
+            let cast_in = CastTy::from_ty(operand.ty(body, tcx)).expect("bad input type for cast");
+            let cast_out = CastTy::from_ty(cast_ty).expect("bad output type for cast");
+            match (cast_in, cast_out) {
+                (CastTy::Ptr(_) | CastTy::FnPtr, CastTy::Int(_)) => {
+                    Err((span, "casting pointers to ints is unstable in const fn".into()))
+                },
+                _ => check_operand(tcx, operand, span, body),
+            }
+        },
+        Rvalue::Cast(CastKind::Pointer(PointerCast::MutToConstPointer | PointerCast::ArrayToPointer), operand, _) => {
+            check_operand(tcx, operand, span, body)
+        },
+        Rvalue::Cast(
+            CastKind::Pointer(
+                PointerCast::UnsafeFnPointer | PointerCast::ClosureFnPointer(_) | PointerCast::ReifyFnPointer,
+            ),
+            _,
+            _,
+        ) => Err((span, "function pointer casts are not allowed in const fn".into())),
+        Rvalue::Cast(CastKind::Pointer(PointerCast::Unsize), op, cast_ty) => {
+            let pointee_ty = if let Some(deref_ty) = cast_ty.builtin_deref(true) {
+                deref_ty.ty
+            } else {
+                // We cannot allow this for now.
+                return Err((span, "unsizing casts are only allowed for references right now".into()));
+            };
+            let unsized_ty = tcx.struct_tail_erasing_lifetimes(pointee_ty, tcx.param_env(def_id));
+            if let ty::Slice(_) | ty::Str = unsized_ty.kind() {
+                check_operand(tcx, op, span, body)?;
+                // Casting/coercing things to slices is fine.
+                Ok(())
+            } else {
+                // We just can't allow trait objects until we have figured out trait method calls.
+                Err((span, "unsizing casts are not allowed in const fn".into()))
+            }
+        },
+        // binops are fine on integers
+        Rvalue::BinaryOp(_, lhs, rhs) | Rvalue::CheckedBinaryOp(_, lhs, rhs) => {
+            check_operand(tcx, lhs, span, body)?;
+            check_operand(tcx, rhs, span, body)?;
+            let ty = lhs.ty(body, tcx);
+            if ty.is_integral() || ty.is_bool() || ty.is_char() {
+                Ok(())
+            } else {
+                Err((
+                    span,
+                    "only int, `bool` and `char` operations are stable in const fn".into(),
+                ))
+            }
+        },
+        Rvalue::NullaryOp(NullOp::SizeOf, _) => Ok(()),
+        Rvalue::NullaryOp(NullOp::Box, _) => Err((span, "heap allocations are not allowed in const fn".into())),
+        Rvalue::UnaryOp(_, operand) => {
+            let ty = operand.ty(body, tcx);
+            if ty.is_integral() || ty.is_bool() {
+                check_operand(tcx, operand, span, body)
+            } else {
+                Err((span, "only int and `bool` operations are stable in const fn".into()))
+            }
+        },
+        Rvalue::Aggregate(_, operands) => {
+            for operand in operands {
+                check_operand(tcx, operand, span, body)?;
+            }
+            Ok(())
+        },
+    }
+}
+
+fn check_statement(tcx: TyCtxt<'tcx>, body: &Body<'tcx>, def_id: DefId, statement: &Statement<'tcx>) -> McfResult {
+    let span = statement.source_info.span;
+    match &statement.kind {
+        StatementKind::Assign(box (place, rval)) => {
+            check_place(tcx, *place, span, body)?;
+            check_rvalue(tcx, body, def_id, rval, span)
+        },
+
+        StatementKind::FakeRead(_, place) |
+        // just an assignment
+        StatementKind::SetDiscriminant { place, .. } => check_place(tcx, **place, span, body),
+
+        StatementKind::LlvmInlineAsm { .. } => Err((span, "cannot use inline assembly in const fn".into())),
+
+        // These are all NOPs
+        StatementKind::StorageLive(_)
+        | StatementKind::StorageDead(_)
+        | StatementKind::Retag { .. }
+        | StatementKind::AscribeUserType(..)
+        | StatementKind::Coverage(..)
+        | StatementKind::Nop => Ok(()),
+    }
+}
+
+fn check_operand(tcx: TyCtxt<'tcx>, operand: &Operand<'tcx>, span: Span, body: &Body<'tcx>) -> McfResult {
+    match operand {
+        Operand::Move(place) | Operand::Copy(place) => check_place(tcx, *place, span, body),
+        Operand::Constant(c) => match c.check_static_ptr(tcx) {
+            Some(_) => Err((span, "cannot access `static` items in const fn".into())),
+            None => Ok(()),
+        },
+    }
+}
+
+fn check_place(tcx: TyCtxt<'tcx>, place: Place<'tcx>, span: Span, body: &Body<'tcx>) -> McfResult {
+    let mut cursor = place.projection.as_ref();
+    while let [ref proj_base @ .., elem] = *cursor {
+        cursor = proj_base;
+        match elem {
+            ProjectionElem::Field(..) => {
+                let base_ty = Place::ty_from(place.local, &proj_base, body, tcx).ty;
+                if let Some(def) = base_ty.ty_adt_def() {
+                    // No union field accesses in `const fn`
+                    if def.is_union() {
+                        return Err((span, "accessing union fields is unstable".into()));
+                    }
+                }
+            },
+            ProjectionElem::ConstantIndex { .. }
+            | ProjectionElem::Downcast(..)
+            | ProjectionElem::Subslice { .. }
+            | ProjectionElem::Deref
+            | ProjectionElem::Index(_) => {},
+        }
+    }
+
+    Ok(())
+}
+
+fn check_terminator(tcx: TyCtxt<'tcx>, body: &'a Body<'tcx>, terminator: &Terminator<'tcx>) -> McfResult {
+    let span = terminator.source_info.span;
+    match &terminator.kind {
+        TerminatorKind::FalseEdge { .. }
+        | TerminatorKind::FalseUnwind { .. }
+        | TerminatorKind::Goto { .. }
+        | TerminatorKind::Return
+        | TerminatorKind::Resume
+        | TerminatorKind::Unreachable => Ok(()),
+
+        TerminatorKind::Drop { place, .. } => check_place(tcx, *place, span, body),
+        TerminatorKind::DropAndReplace { place, value, .. } => {
+            check_place(tcx, *place, span, body)?;
+            check_operand(tcx, value, span, body)
+        },
+
+        TerminatorKind::SwitchInt {
+            discr,
+            switch_ty: _,
+            values: _,
+            targets: _,
+        } => check_operand(tcx, discr, span, body),
+
+        TerminatorKind::Abort => Err((span, "abort is not stable in const fn".into())),
+        TerminatorKind::GeneratorDrop | TerminatorKind::Yield { .. } => {
+            Err((span, "const fn generators are unstable".into()))
+        },
+
+        TerminatorKind::Call {
+            func,
+            args,
+            from_hir_call: _,
+            destination: _,
+            cleanup: _,
+            fn_span: _,
+        } => {
+            let fn_ty = func.ty(body, tcx);
+            if let ty::FnDef(fn_def_id, _) = *fn_ty.kind() {
+                if !rustc_mir::const_eval::is_min_const_fn(tcx, fn_def_id) {
+                    return Err((
+                        span,
+                        format!(
+                            "can only call other `const fn` within a `const fn`, \
+                             but `{:?}` is not stable as `const fn`",
+                            func,
+                        )
+                        .into(),
+                    ));
+                }
+
+                // HACK: This is to "unstabilize" the `transmute` intrinsic
+                // within const fns. `transmute` is allowed in all other const contexts.
+                // This won't really scale to more intrinsics or functions. Let's allow const
+                // transmutes in const fn before we add more hacks to this.
+                if tcx.fn_sig(fn_def_id).abi() == RustIntrinsic && tcx.item_name(fn_def_id) == sym::transmute {
+                    return Err((
+                        span,
+                        "can only call `transmute` from const items, not `const fn`".into(),
+                    ));
+                }
+
+                check_operand(tcx, func, span, body)?;
+
+                for arg in args {
+                    check_operand(tcx, arg, span, body)?;
+                }
+                Ok(())
+            } else {
+                Err((span, "can only call other const fns within const fn".into()))
+            }
+        },
+
+        TerminatorKind::Assert {
+            cond,
+            expected: _,
+            msg: _,
+            target: _,
+            cleanup: _,
+        } => check_operand(tcx, cond, span, body),
+
+        TerminatorKind::InlineAsm { .. } => Err((span, "cannot use inline assembly in const fn".into())),
+    }
+}