Auto merge of #100245 - matthiaskrgr:rollup-tfoo650, r=matthiaskrgr

Rollup of 6 pull requests

Successful merges:

 - #100019 (Revive suggestions for boxed trait objects instead of impl Trait)
 - #100038 (Document the `no-std` target option in config.toml.example)
 - #100194 (Remove even more box syntax uses from src/test)
 - #100206 (test: skip terminfo parsing in Miri)
 - #100230 (Use start_point instead of next_point to point to elided lifetime amp…)
 - #100244 (Add armv4t-none-eabi take2)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_ast_lowering/src/lib.rs

@@ -1228,7 +1228,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     } else {
                         self.next_node_id()
                     };
-                    let span = self.tcx.sess.source_map().next_point(t.span.shrink_to_lo());
+                    let span = self.tcx.sess.source_map().start_point(t.span);
                     Lifetime { ident: Ident::new(kw::UnderscoreLifetime, span), id }
                 });
                 let lifetime = self.lower_lifetime(&region);

compiler/rustc_resolve/src/late.rs

@@ -629,7 +629,7 @@ impl<'a: 'ast, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
                 // Elided lifetime in reference: we resolve as if there was some lifetime `'_` with
                 // NodeId `ty.id`.
                 // This span will be used in case of elision failure.
-                let span = self.r.session.source_map().next_point(ty.span.shrink_to_lo());
+                let span = self.r.session.source_map().start_point(ty.span);
                 self.resolve_elided_lifetime(ty.id, span);
                 visit::walk_ty(self, ty);
             }

compiler/rustc_target/src/spec/armv4t_none_eabi.rs

@@ -0,0 +1,54 @@
+//! Targets the ARMv4T, with code as `a32` code by default.
+//!
+//! Primarily of use for the GBA, but usable with other devices too.
+//!
+//! Please ping @Lokathor if changes are needed.
+//!
+//! This target profile assumes that you have the ARM binutils in your path
+//! (specifically the linker, `arm-none-eabi-ld`). They can be obtained for free
+//! for all major OSes from the ARM developer's website, and they may also be
+//! available in your system's package manager. Unfortunately, the standard
+//! linker that Rust uses (`lld`) only supports as far back as `ARMv5TE`, so we
+//! must use the GNU `ld` linker.
+//!
+//! **Important:** This target profile **does not** specify a linker script. You
+//! just get the default link script when you build a binary for this target.
+//! The default link script is very likely wrong, so you should use
+//! `-Clink-arg=-Tmy_script.ld` to override that with a correct linker script.
+
+use crate::spec::{cvs, LinkerFlavor, PanicStrategy, RelocModel, Target, TargetOptions};
+
+pub fn target() -> Target {
+    Target {
+        llvm_target: "armv4t-none-eabi".into(),
+        pointer_width: 32,
+        arch: "arm".into(),
+        /* Data layout args are '-' separated:
+         * little endian
+         * stack is 64-bit aligned (EABI)
+         * pointers are 32-bit
+         * i64 must be 64-bit aligned (EABI)
+         * mangle names with ELF style
+         * native integers are 32-bit
+         * All other elements are default
+         */
+        data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".into(),
+        options: TargetOptions {
+            abi: "eabi".into(),
+            linker_flavor: LinkerFlavor::Ld,
+            linker: Some("arm-none-eabi-ld".into()),
+            asm_args: cvs!["-mthumb-interwork", "-march=armv4t", "-mlittle-endian",],
+            features: "+soft-float,+strict-align".into(),
+            main_needs_argc_argv: false,
+            atomic_cas: false,
+            has_thumb_interworking: true,
+            relocation_model: RelocModel::Static,
+            panic_strategy: PanicStrategy::Abort,
+            // from thumb_base, rust-lang/rust#44993.
+            emit_debug_gdb_scripts: false,
+            // from thumb_base, apparently gcc/clang give enums a minimum of 8 bits on no-os targets
+            c_enum_min_bits: 8,
+            ..Default::default()
+        },
+    }
+}

compiler/rustc_typeck/src/check/_match.rs

@@ -4,7 +4,7 @@ use rustc_errors::{Applicability, MultiSpan};
 use rustc_hir::{self as hir, ExprKind};
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use rustc_infer::traits::Obligation;
-use rustc_middle::ty::{self, ToPredicate, Ty, TypeVisitable};
+use rustc_middle::ty::{self, ToPredicate, Ty};
 use rustc_span::Span;
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
 use rustc_trait_selection::traits::{
@@ -94,7 +94,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             let arm_ty = self.check_expr_with_expectation(&arm.body, expected);
             all_arms_diverge &= self.diverges.get();
 
-            let opt_suggest_box_span = self.opt_suggest_box_span(arm_ty, orig_expected);
+            let opt_suggest_box_span = prior_arm.and_then(|(_, prior_arm_ty, _)| {
+                self.opt_suggest_box_span(prior_arm_ty, arm_ty, orig_expected)
+            });
 
             let (arm_block_id, arm_span) = if let hir::ExprKind::Block(blk, _) = arm.body.kind {
                 (Some(blk.hir_id), self.find_block_span(blk))
@@ -473,43 +475,48 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     // provide a structured suggestion in that case.
     pub(crate) fn opt_suggest_box_span(
         &self,
-        outer_ty: Ty<'tcx>,
+        first_ty: Ty<'tcx>,
+        second_ty: Ty<'tcx>,
         orig_expected: Expectation<'tcx>,
     ) -> Option<Span> {
         match orig_expected {
             Expectation::ExpectHasType(expected)
                 if self.in_tail_expr
-                    && self.ret_coercion.as_ref()?.borrow().merged_ty().has_opaque_types()
-                    && self.can_coerce(outer_ty, expected) =>
+                    && self.return_type_has_opaque
+                    && self.can_coerce(first_ty, expected)
+                    && self.can_coerce(second_ty, expected) =>
             {
                 let obligations = self.fulfillment_cx.borrow().pending_obligations();
                 let mut suggest_box = !obligations.is_empty();
-                for o in obligations {
-                    match o.predicate.kind().skip_binder() {
-                        ty::PredicateKind::Trait(t) => {
-                            let pred =
-                                ty::Binder::dummy(ty::PredicateKind::Trait(ty::TraitPredicate {
-                                    trait_ref: ty::TraitRef {
-                                        def_id: t.def_id(),
-                                        substs: self.tcx.mk_substs_trait(outer_ty, &[]),
+                'outer: for o in obligations {
+                    for outer_ty in &[first_ty, second_ty] {
+                        match o.predicate.kind().skip_binder() {
+                            ty::PredicateKind::Trait(t) => {
+                                let pred = ty::Binder::dummy(ty::PredicateKind::Trait(
+                                    ty::TraitPredicate {
+                                        trait_ref: ty::TraitRef {
+                                            def_id: t.def_id(),
+                                            substs: self.tcx.mk_substs_trait(*outer_ty, &[]),
+                                        },
+                                        constness: t.constness,
+                                        polarity: t.polarity,
                                     },
-                                    constness: t.constness,
-                                    polarity: t.polarity,
-                                }));
-                            let obl = Obligation::new(
-                                o.cause.clone(),
-                                self.param_env,
-                                pred.to_predicate(self.tcx),
-                            );
-                            suggest_box &= self.predicate_must_hold_modulo_regions(&obl);
-                            if !suggest_box {
-                                // We've encountered some obligation that didn't hold, so the
-                                // return expression can't just be boxed. We don't need to
-                                // evaluate the rest of the obligations.
-                                break;
+                                ));
+                                let obl = Obligation::new(
+                                    o.cause.clone(),
+                                    self.param_env,
+                                    pred.to_predicate(self.tcx),
+                                );
+                                suggest_box &= self.predicate_must_hold_modulo_regions(&obl);
+                                if !suggest_box {
+                                    // We've encountered some obligation that didn't hold, so the
+                                    // return expression can't just be boxed. We don't need to
+                                    // evaluate the rest of the obligations.
+                                    break 'outer;
+                                }
                             }
+                            _ => {}
                         }
-                        _ => {}
                     }
                 }
                 // If all the obligations hold (or there are no obligations) the tail expression

compiler/rustc_typeck/src/check/expr.rs

@@ -1002,7 +1002,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             let else_ty = self.check_expr_with_expectation(else_expr, expected);
             let else_diverges = self.diverges.get();
 
-            let opt_suggest_box_span = self.opt_suggest_box_span(else_ty, orig_expected);
+            let opt_suggest_box_span = self.opt_suggest_box_span(then_ty, else_ty, orig_expected);
             let if_cause = self.if_cause(
                 sp,
                 cond_expr.span,

config.toml.example

@@ -721,6 +721,10 @@ changelog-seen = 2
 # probably don't want to use this.
 #qemu-rootfs = <none> (path)
 
+# Skip building the `std` library for this target. Enabled by default for
+# target triples containing `-none`, `nvptx`, `switch`, or `-uefi`.
+#no-std = <platform-specific> (bool)
+
 # =============================================================================
 # Distribution options
 #

library/test/src/term/terminfo/mod.rs

@@ -80,6 +80,17 @@ impl TermInfo {
 
     /// Creates a TermInfo for the named terminal.
     pub(crate) fn from_name(name: &str) -> Result<TermInfo, Error> {
+        if cfg!(miri) {
+            // Avoid all the work of parsing the terminfo (it's pretty slow under Miri), and just
+            // assume that the standard color codes work (like e.g. the 'colored' crate).
+            return Ok(TermInfo {
+                names: Default::default(),
+                bools: Default::default(),
+                numbers: Default::default(),
+                strings: Default::default(),
+            });
+        }
+
         get_dbpath_for_term(name)
             .ok_or_else(|| {
                 Error::IoError(io::Error::new(io::ErrorKind::NotFound, "terminfo file not found"))
@@ -119,13 +130,22 @@ pub(crate) struct TerminfoTerminal<T> {
 impl<T: Write + Send> Terminal for TerminfoTerminal<T> {
     fn fg(&mut self, color: color::Color) -> io::Result<bool> {
         let color = self.dim_if_necessary(color);
+        if cfg!(miri) && color < 8 {
+            // The Miri logic for this only works for the most basic 8 colors, which we just assume
+            // the terminal will support. (`num_colors` is always 0 in Miri, so higher colors will
+            // just fail. But libtest doesn't use any higher colors anyway.)
+            return write!(self.out, "\x1B[3{color}m").and(Ok(true));
+        }
         if self.num_colors > color {
             return self.apply_cap("setaf", &[Param::Number(color as i32)]);
         }
         Ok(false)
     }
 
     fn reset(&mut self) -> io::Result<bool> {
+        if cfg!(miri) {
+            return write!(self.out, "\x1B[0m").and(Ok(true));
+        }
         // are there any terminals that have color/attrs and not sgr0?
         // Try falling back to sgr, then op
         let cmd = match ["sgr0", "sgr", "op"].iter().find_map(|cap| self.ti.strings.get(*cap)) {

src/doc/rustc/src/SUMMARY.md

@@ -18,6 +18,7 @@
     - [aarch64-apple-ios-sim](platform-support/aarch64-apple-ios-sim.md)
     - [\*-apple-watchos\*](platform-support/apple-watchos.md)
     - [aarch64-nintendo-switch-freestanding](platform-support/aarch64-nintendo-switch-freestanding.md)
+    - [armv4t-none-eabi](platform-support/armv4t-none-eabi.md)
     - [armv6k-nintendo-3ds](platform-support/armv6k-nintendo-3ds.md)
     - [armv7-unknown-linux-uclibceabi](platform-support/armv7-unknown-linux-uclibceabi.md)
     - [armv7-unknown-linux-uclibceabihf](platform-support/armv7-unknown-linux-uclibceabihf.md)

src/doc/rustc/src/platform-support/armv4t_none_eabi.md

@@ -0,0 +1,70 @@
+# armv4t-none-eabi
+
+Tier 3
+
+Bare-metal target for any cpu in the ARMv4T architecture family, supporting
+ARM/Thumb code interworking (aka `a32`/`t32`), with ARM code as the default code
+generation.
+
+In particular this supports the Gameboy Advance (GBA), but there's nothing GBA
+specific with this target, so any ARMv4T device should work fine.
+
+## Target Maintainers
+
+* [@Lokathor](https://github.com/lokathor)
+
+## Requirements
+
+The target is cross-compiled, and uses static linking.
+
+The linker that comes with rustc cannot link for this platform (the platform is
+too old). You will need the `arm-none-eabi-ld` linker from a GNU Binutils
+targeting ARM. This can be obtained for Windows/Mac/Linux from the [ARM
+Developer Website][arm-dev], or possibly from your OS's package manager.
+
+[arm-dev]: https://developer.arm.com/Tools%20and%20Software/GNU%20Toolchain
+
+This target doesn't provide a linker script, you'll need to bring your own
+according to the specific device you want to target. Pass
+`-Clink-arg=-Tyour_script.ld` as a rustc argument to make the linker use
+`your_script.ld` during linking.
+
+## Building Rust Programs
+
+Because it is Tier 3, rust does not yet ship pre-compiled artifacts for this target.
+
+Just use the `build-std` nightly cargo feature to build the `core` library. You
+can pass this as a command line argument to cargo, or your `.cargo/config.toml`
+file might include the following lines:
+
+```toml
+[unstable]
+build-std = ["core"]
+```
+
+Most of `core` should work as expected, with the following notes:
+* the target is "soft float", so `f32` and `f64` operations are emulated in
+  software.
+* integer division is also emulated in software.
+* the target is old enough that it doesn't have atomic instructions.
+
+Rust programs are output as ELF files.
+
+For running on hardware, you'll generally need to extract the "raw" program code
+out of the ELF and into a file of its own. The `objcopy` program provided as
+part of the GNU Binutils can do this:
+
+```shell
+arm-none-eabi-objcopy --output-target binary [in_file] [out_file]
+```
+
+## Testing
+
+This is a cross-compiled target that you will need to emulate during testing.
+
+Because this is a device-agnostic target, and the exact emulator that you'll
+need depends on the specific device you want to run your code on.
+
+For example, when programming for the Gameboy Advance, the
+[mgba-test-runner](https://github.com/agbrs/agb) program could be used to make a
+normal set of rust tests be run within the `mgba` emulator.

src/test/mir-opt/simplify-locals.rs

@@ -1,6 +1,6 @@
 // unit-test: SimplifyLocals
 
-#![feature(box_syntax)]
+
 #![feature(thread_local)]
 
 #[derive(Copy, Clone)]