Auto merge of #47900 - kennytm:rollup, r=kennytm

Rollup of 16 pull requests

- Successful merges: #47838, #47840, #47844, #47874, #47875, #47876, #47884, #47886, #47889, #47890, #47891, #47795, #47677, #47893, #47895, #47552
- Failed merges:

src/bootstrap/builder.rs

@@ -377,6 +377,11 @@ impl<'a> Builder<'a> {
         self.ensure(Libdir { compiler, target })
     }
 
+    pub fn sysroot_codegen_backends(&self, compiler: Compiler) -> PathBuf {
+        self.sysroot_libdir(compiler, compiler.host)
+            .with_file_name("codegen-backends")
+    }
+
     /// Returns the compiler's libdir where it stores the dynamic libraries that
     /// it itself links against.
     ///

src/bootstrap/compile.rs

@@ -724,8 +724,7 @@ fn copy_codegen_backends_to_sysroot(builder: &Builder,
     //
     // Here we're looking for the output dylib of the `CodegenBackend` step and
     // we're copying that into the `codegen-backends` folder.
-    let libdir = builder.sysroot_libdir(target_compiler, target);
-    let dst = libdir.join("codegen-backends");
+    let dst = builder.sysroot_codegen_backends(target_compiler);
     t!(fs::create_dir_all(&dst));
 
     for backend in builder.config.rust_codegen_backends.iter() {

src/bootstrap/dist.rs

@@ -435,11 +435,9 @@ impl Step for Rustc {
             }
 
             // Copy over the codegen backends
-            let backends_src = builder.sysroot_libdir(compiler, host)
-                .join("codegen-backends");
-            let backends_dst = image.join("lib/rustlib")
-                .join(&*host)
-                .join("lib/codegen-backends");
+            let backends_src = builder.sysroot_codegen_backends(compiler);
+            let backends_rel = backends_src.strip_prefix(&src).unwrap();
+            let backends_dst = image.join(&backends_rel);
             t!(fs::create_dir_all(&backends_dst));
             cp_r(&backends_src, &backends_dst);
 

src/libcore/fmt/mod.rs

@@ -1586,6 +1586,7 @@ impl Display for ! {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Debug for bool {
+    #[inline]
     fn fmt(&self, f: &mut Formatter) -> Result {
         Display::fmt(self, f)
     }
@@ -1748,6 +1749,7 @@ impl<T: Debug> Debug for [T] {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Debug for () {
+    #[inline]
     fn fmt(&self, f: &mut Formatter) -> Result {
         f.pad("()")
     }

src/libcore/fmt/num.rs

@@ -157,6 +157,7 @@ macro_rules! debug {
     ($T:ident) => {
         #[stable(feature = "rust1", since = "1.0.0")]
         impl fmt::Debug for $T {
+            #[inline]
             fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
                 fmt::Display::fmt(self, f)
             }

src/libcore/iter/mod.rs

@@ -307,6 +307,7 @@ use fmt;
 use iter_private::TrustedRandomAccess;
 use ops::Try;
 use usize;
+use intrinsics;
 
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::iterator::Iterator;
@@ -694,6 +695,49 @@ impl<I> Iterator for StepBy<I> where I: Iterator {
             (f(inner_hint.0), inner_hint.1.map(f))
         }
     }
+
+    #[inline]
+    fn nth(&mut self, mut n: usize) -> Option<Self::Item> {
+        if self.first_take {
+            self.first_take = false;
+            let first = self.iter.next();
+            if n == 0 {
+                return first;
+            }
+            n -= 1;
+        }
+        // n and self.step are indices, we need to add 1 to get the amount of elements
+        // When calling `.nth`, we need to subtract 1 again to convert back to an index
+        // step + 1 can't overflow because `.step_by` sets `self.step` to `step - 1`
+        let mut step = self.step + 1;
+        // n + 1 could overflow
+        // thus, if n is usize::MAX, instead of adding one, we call .nth(step)
+        if n == usize::MAX {
+            self.iter.nth(step - 1);
+        } else {
+            n += 1;
+        }
+
+        // overflow handling
+        loop {
+            let mul = n.checked_mul(step);
+            if unsafe { intrinsics::likely(mul.is_some()) } {
+                return self.iter.nth(mul.unwrap() - 1);
+            }
+            let div_n = usize::MAX / n;
+            let div_step = usize::MAX / step;
+            let nth_n = div_n * n;
+            let nth_step = div_step * step;
+            let nth = if nth_n > nth_step {
+                step -= div_n;
+                nth_n
+            } else {
+                n -= div_step;
+                nth_step
+            };
+            self.iter.nth(nth - 1);
+        }
+    }
 }
 
 // StepBy can only make the iterator shorter, so the len will still fit.

src/libcore/tests/iter.rs

@@ -161,6 +161,68 @@ fn test_iterator_step_by() {
     assert_eq!(it.next(), None);
 }
 
+#[test]
+fn test_iterator_step_by_nth() {
+    let mut it = (0..16).step_by(5);
+    assert_eq!(it.nth(0), Some(0));
+    assert_eq!(it.nth(0), Some(5));
+    assert_eq!(it.nth(0), Some(10));
+    assert_eq!(it.nth(0), Some(15));
+    assert_eq!(it.nth(0), None);
+
+    let it = (0..18).step_by(5);
+    assert_eq!(it.clone().nth(0), Some(0));
+    assert_eq!(it.clone().nth(1), Some(5));
+    assert_eq!(it.clone().nth(2), Some(10));
+    assert_eq!(it.clone().nth(3), Some(15));
+    assert_eq!(it.clone().nth(4), None);
+    assert_eq!(it.clone().nth(42), None);
+}
+
+#[test]
+fn test_iterator_step_by_nth_overflow() {
+    #[cfg(target_pointer_width = "8")]
+    type Bigger = u16;
+    #[cfg(target_pointer_width = "16")]
+    type Bigger = u32;
+    #[cfg(target_pointer_width = "32")]
+    type Bigger = u64;
+    #[cfg(target_pointer_width = "64")]
+    type Bigger = u128;
+
+    #[derive(Clone)]
+    struct Test(Bigger);
+    impl<'a> Iterator for &'a mut Test {
+        type Item = i32;
+        fn next(&mut self) -> Option<Self::Item> { Some(21) }
+        fn nth(&mut self, n: usize) -> Option<Self::Item> {
+            self.0 += n as Bigger + 1;
+            Some(42)
+        }
+    }
+
+    let mut it = Test(0);
+    let root = usize::MAX >> (::std::mem::size_of::<usize>() * 8 / 2);
+    let n = root + 20;
+    (&mut it).step_by(n).nth(n);
+    assert_eq!(it.0, n as Bigger * n as Bigger);
+
+    // large step
+    let mut it = Test(0);
+    (&mut it).step_by(usize::MAX).nth(5);
+    assert_eq!(it.0, (usize::MAX as Bigger) * 5);
+
+    // n + 1 overflows
+    let mut it = Test(0);
+    (&mut it).step_by(2).nth(usize::MAX);
+    assert_eq!(it.0, (usize::MAX as Bigger) * 2);
+
+    // n + 1 overflows
+    let mut it = Test(0);
+    (&mut it).step_by(1).nth(usize::MAX);
+    assert_eq!(it.0, (usize::MAX as Bigger) * 1);
+}
+
 #[test]
 #[should_panic]
 fn test_iterator_step_by_zero() {

src/libpanic_abort/lib.rs

@@ -27,10 +27,12 @@
 #![feature(libc)]
 #![feature(panic_runtime)]
 #![feature(staged_api)]
+#![feature(rustc_attrs)]
 
 // Rust's "try" function, but if we're aborting on panics we just call the
 // function as there's nothing else we need to do here.
 #[no_mangle]
+#[rustc_std_internal_symbol]
 pub unsafe extern fn __rust_maybe_catch_panic(f: fn(*mut u8),
                                               data: *mut u8,
                                               _data_ptr: *mut usize,
@@ -50,6 +52,7 @@ pub unsafe extern fn __rust_maybe_catch_panic(f: fn(*mut u8),
 // will kill us with an illegal instruction, which will do a good enough job for
 // now hopefully.
 #[no_mangle]
+#[rustc_std_internal_symbol]
 pub unsafe extern fn __rust_start_panic(_data: usize, _vtable: usize) -> u32 {
     abort();
 

src/librustc/README.md

@@ -176,6 +176,7 @@ pointers for understanding them better.
 - `'gcx` -- the lifetime of the global arena (see `librustc/ty`).
 - generics -- the set of generic type parameters defined on a type or item
 - ICE -- internal compiler error. When the compiler crashes.
+- ICH -- incremental compilation hash.
 - infcx -- the inference context (see `librustc/infer`)
 - MIR -- the **Mid-level IR** that is created after type-checking for use by borrowck and trans.
   Defined in the `src/librustc/mir/` module, but much of the code that manipulates it is

src/librustc/dep_graph/dep_node.rs

@@ -639,6 +639,9 @@ define_dep_nodes!( <'tcx>
     [] TargetFeaturesEnabled(DefId),
 
     [] InstanceDefSizeEstimate { instance_def: InstanceDef<'tcx> },
+
+    [] GetSymbolExportLevel(DefId),
+
 );
 
 trait DepNodeParams<'a, 'gcx: 'tcx + 'a, 'tcx: 'a> : fmt::Debug {

src/librustc/traits/error_reporting.rs

@@ -831,6 +831,11 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                 span,
                 node: hir::ImplItemKind::Method(hir::MethodSig { ref decl, .. }, _),
                 ..
+            }) |
+            hir::map::NodeTraitItem(&hir::TraitItem {
+                span,
+                node: hir::TraitItemKind::Method(hir::MethodSig { ref decl, .. }, _),
+                ..
             }) => {
                 (self.tcx.sess.codemap().def_span(span), decl.inputs.iter()
                         .map(|arg| match arg.clone().into_inner().node {

src/librustc/ty/maps/mod.rs

@@ -343,6 +343,7 @@ define_maps! { <'tcx>
         -> (Arc<DefIdSet>, Arc<Vec<Arc<CodegenUnit<'tcx>>>>),
     [] fn export_name: ExportName(DefId) -> Option<Symbol>,
     [] fn contains_extern_indicator: ContainsExternIndicator(DefId) -> bool,
+    [] fn symbol_export_level: GetSymbolExportLevel(DefId) -> SymbolExportLevel,
     [] fn is_translated_function: IsTranslatedFunction(DefId) -> bool,
     [] fn codegen_unit: CodegenUnit(InternedString) -> Arc<CodegenUnit<'tcx>>,
     [] fn compile_codegen_unit: CompileCodegenUnit(InternedString) -> Stats,

src/librustc/ty/maps/plumbing.rs

@@ -921,6 +921,8 @@ pub fn force_from_dep_node<'a, 'gcx, 'lcx>(tcx: TyCtxt<'a, 'gcx, 'lcx>,
 
         DepKind::TargetFeaturesWhitelist => { force!(target_features_whitelist, LOCAL_CRATE); }
         DepKind::TargetFeaturesEnabled => { force!(target_features_enabled, def_id!()); }
+
+        DepKind::GetSymbolExportLevel => { force!(symbol_export_level, def_id!()); }
     }
 
     true

src/librustc_back/target/mod.rs

@@ -468,6 +468,10 @@ pub struct TargetOptions {
 
     /// The codegen backend to use for this target, typically "llvm"
     pub codegen_backend: String,
+
+    /// The default visibility for symbols in this target should be "hidden"
+    /// rather than "default"
+    pub default_hidden_visibility: bool,
 }
 
 impl Default for TargetOptions {
@@ -538,6 +542,7 @@ impl Default for TargetOptions {
             no_builtins: false,
             i128_lowering: false,
             codegen_backend: "llvm".to_string(),
+            default_hidden_visibility: false,
         }
     }
 }
@@ -785,6 +790,7 @@ impl Target {
         key!(singlethread, bool);
         key!(no_builtins, bool);
         key!(codegen_backend);
+        key!(default_hidden_visibility, bool);
 
         if let Some(array) = obj.find("abi-blacklist").and_then(Json::as_array) {
             for name in array.iter().filter_map(|abi| abi.as_string()) {
@@ -982,6 +988,7 @@ impl ToJson for Target {
         target_option_val!(singlethread);
         target_option_val!(no_builtins);
         target_option_val!(codegen_backend);
+        target_option_val!(default_hidden_visibility);
 
         if default.abi_blacklist != self.options.abi_blacklist {
             d.insert("abi-blacklist".to_string(), self.options.abi_blacklist.iter()

src/librustc_back/target/msp430_none_elf.rs

@@ -53,6 +53,12 @@ pub fn target() -> TargetResult {
             // don't want to invoke that many gcc instances.
             default_codegen_units: Some(1),
 
+            // Since MSP430 doesn't meaningfully support faulting on illegal
+            // instructions, LLVM generates a call to abort() function instead
+            // of a trap instruction. Such calls are 4 bytes long, and that is
+            // too much overhead for such small target.
+            trap_unreachable: false,
+
             .. Default::default( )
         }
     })

src/librustc_back/target/wasm32_unknown_unknown.rs

@@ -83,6 +83,9 @@ pub fn target() -> Result<Target, String> {
         // performing LTO with compiler-builtins.
         no_builtins: true,
 
+        // no dynamic linking, no need for default visibility!
+        default_hidden_visibility: true,
+
         .. Default::default()
     };
     Ok(Target {

src/librustc_const_eval/check_match.rs

@@ -127,20 +127,27 @@ impl<'a, 'tcx> Visitor<'tcx> for MatchVisitor<'a, 'tcx> {
     }
 }
 
+
 impl<'a, 'tcx> PatternContext<'a, 'tcx> {
     fn report_inlining_errors(&self, pat_span: Span) {
         for error in &self.errors {
             match *error {
                 PatternError::StaticInPattern(span) => {
-                    span_err!(self.tcx.sess, span, E0158,
-                              "statics cannot be referenced in patterns");
+                    self.span_e0158(span, "statics cannot be referenced in patterns")
+                }
+                PatternError::AssociatedConstInPattern(span) => {
+                    self.span_e0158(span, "associated consts cannot be referenced in patterns")
                 }
                 PatternError::ConstEval(ref err) => {
                     err.report(self.tcx, pat_span, "pattern");
                 }
             }
         }
     }
+
+    fn span_e0158(&self, span: Span, text: &str) {
+        span_err!(self.tcx.sess, span, E0158, "{}", text)
+    }
 }
 
 impl<'a, 'tcx> MatchVisitor<'a, 'tcx> {

src/librustc_const_eval/pattern.rs

@@ -27,6 +27,7 @@ use syntax_pos::Span;
 
 #[derive(Clone, Debug)]
 pub enum PatternError<'tcx> {
+    AssociatedConstInPattern(Span),
     StaticInPattern(Span),
     ConstEval(ConstEvalErr<'tcx>),
 }
@@ -635,6 +636,10 @@ impl<'a, 'tcx> PatternContext<'a, 'tcx> {
                   -> Pattern<'tcx> {
         let ty = self.tables.node_id_to_type(id);
         let def = self.tables.qpath_def(qpath, id);
+        let is_associated_const = match def {
+            Def::AssociatedConst(_) => true,
+            _ => false,
+        };
         let kind = match def {
             Def::Const(def_id) | Def::AssociatedConst(def_id) => {
                 let substs = self.tables.node_substs(id);
@@ -656,7 +661,11 @@ impl<'a, 'tcx> PatternContext<'a, 'tcx> {
                         return pat;
                     }
                     None => {
-                        self.errors.push(PatternError::StaticInPattern(span));
+                        self.errors.push(if is_associated_const {
+                            PatternError::AssociatedConstInPattern(span)
+                        } else {
+                            PatternError::StaticInPattern(span)
+                        });
                         PatternKind::Wild
                     }
                 }