Auto merge of #69293 - Dylan-DPC:rollup-imcbvgo, r=Dylan-DPC

Rollup of 5 pull requests

Successful merges:

 - #68863 (ci: switch macOS builders to 10.15)
 - #69142 (Add shared script for linkchecking books.)
 - #69248 (Don't eliminate frame pointers on thumb targets)
 - #69280 (Remove special case for `simd_shuffle` arg promotion)
 - #69284 (Reword OpenOptions::{create, create_new} doc.)

Failed merges:

r? @ghost

Author: bors

src/bootstrap/test.rs

@@ -1051,10 +1051,10 @@ impl Step for Compiletest {
         cmd.arg("--docck-python").arg(builder.python());
 
         if builder.config.build.ends_with("apple-darwin") {
-            // Force /usr/bin/python on macOS for LLDB tests because we're loading the
+            // Force /usr/bin/python3 on macOS for LLDB tests because we're loading the
             // LLDB plugin's compiled module which only works with the system python
             // (namely not Homebrew-installed python)
-            cmd.arg("--lldb-python").arg("/usr/bin/python");
+            cmd.arg("--lldb-python").arg("/usr/bin/python3");
         } else {
             cmd.arg("--lldb-python").arg(builder.python());
         }

src/ci/azure-pipelines/auto.yml

@@ -63,7 +63,7 @@ jobs:
 - job: macOS
   timeoutInMinutes: 600
   pool:
-    vmImage: macos-10.13
+    vmImage: macos-10.15
   steps:
   - template: steps/run.yml
   strategy:

src/ci/azure-pipelines/steps/run.yml

@@ -51,10 +51,6 @@ steps:
   displayName: Install clang
   condition: and(succeeded(), not(variables.SKIP_JOB))
 
-- bash: src/ci/scripts/switch-xcode.sh
-  displayName: Switch to Xcode 9.3
-  condition: and(succeeded(), not(variables.SKIP_JOB))
-
 - bash: src/ci/scripts/install-wix.sh
   displayName: Install wix
   condition: and(succeeded(), not(variables.SKIP_JOB))

src/ci/azure-pipelines/try.yml

@@ -25,7 +25,7 @@ jobs:
 # - job: macOS
 #   timeoutInMinutes: 600
 #   pool:
-#     vmImage: macos-10.13
+#     vmImage: macos-10.15
 #   steps:
 #   - template: steps/run.yml
 #   strategy:

src/ci/scripts/install-clang.sh

@@ -19,9 +19,7 @@ if isMacOS; then
     # native clang is configured to use the correct path, but our custom one
     # doesn't. This sets the SDKROOT environment variable to the SDK so that
     # our own clang can figure out the correct include path on its own.
-    if ! [[ -d "/usr/include" ]]; then
-        ciCommandSetEnv SDKROOT "$(xcrun --sdk macosx --show-sdk-path)"
-    fi
+    ciCommandSetEnv SDKROOT "$(xcrun --sdk macosx --show-sdk-path)"
 
     # Configure `AR` specifically so rustbuild doesn't try to infer it as
     # `clang-ar` by accident.

src/ci/scripts/switch-xcode.sh

@@ -72,8 +72,8 @@ fn eval_body_using_ecx<'mir, 'tcx>(
     Ok(ret)
 }
 
-/// The `InterpCx` is only meant to be used to do field and index projections into constants for
-/// `simd_shuffle` and const patterns in match arms.
+/// The `InterpCx` is only meant to be used to do field and index projections into promoteds
+/// and const patterns in match arms.
 ///
 /// The function containing the `match` that is currently being analyzed may have generic bounds
 /// that inform us about the generic bounds of the constant. E.g., using an associated constant

src/librustc_mir/const_eval/eval_queries.rs

@@ -24,7 +24,6 @@ use rustc_span::{Span, DUMMY_SP};
 use syntax::ast::LitKind;
 
 use rustc_index::vec::{Idx, IndexVec};
-use rustc_target::spec::abi::Abi;
 
 use std::cell::Cell;
 use std::{cmp, iter, mem, usize};
@@ -106,11 +105,10 @@ pub enum Candidate {
     /// Promotion of the `x` in `[x; 32]`.
     Repeat(Location),
 
-    /// Currently applied to function calls where the callee has the unstable
-    /// `#[rustc_args_required_const]` attribute as well as the SIMD shuffle
-    /// intrinsic. The intrinsic requires the arguments are indeed constant and
-    /// the attribute currently provides the semantic requirement that arguments
-    /// must be constant.
+    /// Function calls where the callee has the unstable
+    /// `#[rustc_args_required_const]` attribute. The attribute requires that
+    /// the arguments be constant, usually because they are encoded as an
+    /// immediate operand in a platform intrinsic.
     Argument { bb: BasicBlock, index: usize },
 }
 
@@ -218,17 +216,6 @@ impl<'tcx> Visitor<'tcx> for Collector<'_, 'tcx> {
 
         if let TerminatorKind::Call { ref func, .. } = *kind {
             if let ty::FnDef(def_id, _) = func.ty(self.body, self.tcx).kind {
-                let fn_sig = self.tcx.fn_sig(def_id);
-                if let Abi::RustIntrinsic | Abi::PlatformIntrinsic = fn_sig.abi() {
-                    let name = self.tcx.item_name(def_id);
-                    // FIXME(eddyb) use `#[rustc_args_required_const(2)]` for shuffles.
-                    if name.as_str().starts_with("simd_shuffle") {
-                        self.candidates.push(Candidate::Argument { bb: location.block, index: 2 });
-
-                        return; // Don't double count `simd_shuffle` candidates
-                    }
-                }
-
                 if let Some(constant_args) = args_required_const(self.tcx, def_id) {
                     for index in constant_args {
                         self.candidates.push(Candidate::Argument { bb: location.block, index });
@@ -730,8 +717,7 @@ pub fn validate_candidates(
         .filter(|&candidate| {
             validator.explicit = candidate.forces_explicit_promotion();
 
-            // FIXME(eddyb) also emit the errors for shuffle indices
-            // and `#[rustc_args_required_const]` arguments here.
+            // FIXME(eddyb) also emit the errors for `#[rustc_args_required_const]` arguments here.
 
             let is_promotable = validator.validate_candidate(candidate).is_ok();
             match candidate {

src/librustc_mir/transform/promote_consts.rs

@@ -50,6 +50,9 @@ pub fn opts() -> TargetOptions {
         // until we figure a way to add the pretty printers without requiring a volatile load cf.
         // rust-lang/rust#44993.
         emit_debug_gdb_scripts: false,
+        // LLVM is eager to trash the link register when calling `noreturn` functions, which
+        // breaks debugging. Preserve LR by default to prevent that from happening.
+        eliminate_frame_pointer: false,
         ..Default::default()
     }
 }

src/librustc_target/spec/thumb_base.rs

@@ -844,10 +844,7 @@ impl OpenOptions {
         self
     }
 
-    /// Sets the option for creating a new file.
-    ///
-    /// This option indicates whether a new file will be created if the file
-    /// does not yet already exist.
+    /// Sets the option to create a new file, or open it if it already exists.
     ///
     /// In order for the file to be created, [`write`] or [`append`] access must
     /// be used.
@@ -868,11 +865,10 @@ impl OpenOptions {
         self
     }
 
-    /// Sets the option to always create a new file.
+    /// Sets the option to create a new file, failing if it already exists.
     ///
-    /// This option indicates whether a new file will be created.
-    /// No file is allowed to exist at the target location, also no (dangling)
-    /// symlink.
+    /// No file is allowed to exist at the target location, also no (dangling) symlink. In this
+    /// way, if the call succeeds, the file returned is guaranteed to be new.
     ///
     /// This option is useful because it is atomic. Otherwise between checking
     /// whether a file exists and creating a new one, the file may have been