Auto merge of #136119 - Zalathar:rollup-gr7bpkr, r=Zalathar

Rollup of 6 pull requests

Successful merges:

 - #135876 (fix doc for std::sync::mpmc)
 - #135961 (Fix 2/4 tests skipped by opt-dist)
 - #136037 (Mark all NuttX targets as tier 3 target and support the standard library)
 - #136098 (Downgrade `linker-warnings` to allow-by-default)
 - #136110 (Miri subtree update)
 - #136117 (Subtree update of `rust-analyzer`)

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

Author: bors

compiler/rustc_lint_defs/src/builtin.rs

@@ -4091,6 +4091,7 @@ declare_lint! {
     /// ### Example
     ///
     /// ```rust,ignore (needs CLI args, platform-specific)
+    /// #[warn(linker_messages)]
     /// extern "C" {
     ///   fn foo();
     /// }
@@ -4104,17 +4105,24 @@ declare_lint! {
     ///          >>> referenced by rust_out.69edbd30df4ae57d-cgu.0
     ///          >>>               rust_out.rust_out.69edbd30df4ae57d-cgu.0.rcgu.o:(rust_out::main::h3a90094b06757803)
     ///   |
-    ///   = note: `#[warn(linker_messages)]` on by default
-    ///
+    /// note: the lint level is defined here
+    ///  --> warn.rs:1:9
+    ///   |
+    /// 1 | #![warn(linker_messages)]
+    ///   |         ^^^^^^^^^^^^^^^
     /// warning: 1 warning emitted
     /// ```
     ///
     /// ### Explanation
     ///
-    /// Linkers emit platform-specific and program-specific warnings that cannot be predicted in advance by the rust compiler.
-    /// They are forwarded by default, but can be disabled by adding `#![allow(linker_messages)]` at the crate root.
+    /// Linkers emit platform-specific and program-specific warnings that cannot be predicted in
+    /// advance by the Rust compiler. Such messages are ignored by default for now. While linker
+    /// warnings could be very useful they have been ignored for many years by essentially all
+    /// users, so we need to do a bit more work than just surfacing their text to produce a clear
+    /// and actionable warning of similar quality to our other diagnostics. See this tracking
+    /// issue for more details: <https://github.com/rust-lang/rust/issues/136096>.
     pub LINKER_MESSAGES,
-    Warn,
+    Allow,
     "warnings emitted at runtime by the target-specific linker program"
 }
 

compiler/rustc_target/src/spec/targets/aarch64_unknown_nuttx.rs

@@ -36,7 +36,7 @@ pub(crate) fn target() -> Target {
             description: Some("AArch64 NuttX".into()),
             tier: Some(3),
             host_tools: Some(false),
-            std: Some(false),
+            std: Some(true),
         },
         pointer_width: 64,
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128-Fn32".into(),

compiler/rustc_target/src/spec/targets/armv7a_nuttx_eabi.rs

@@ -31,7 +31,7 @@ pub(crate) fn target() -> Target {
             description: Some("ARMv7-A Cortex-A with NuttX".into()),
             tier: Some(3),
             host_tools: Some(false),
-            std: Some(false),
+            std: Some(true),
         },
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".into(),

compiler/rustc_target/src/spec/targets/armv7a_nuttx_eabihf.rs

@@ -31,7 +31,7 @@ pub(crate) fn target() -> Target {
             description: Some("ARMv7-A Cortex-A with NuttX (hard float)".into()),
             tier: Some(3),
             host_tools: Some(false),
-            std: Some(false),
+            std: Some(true),
         },
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".into(),

compiler/rustc_target/src/spec/targets/riscv32imac_unknown_nuttx_elf.rs

@@ -6,9 +6,9 @@ pub(crate) fn target() -> Target {
         llvm_target: "riscv32".into(),
         metadata: crate::spec::TargetMetadata {
             description: None,
-            tier: None,
+            tier: Some(3),
             host_tools: None,
-            std: None,
+            std: Some(true),
         },
         pointer_width: 32,
         arch: "riscv32".into(),

compiler/rustc_target/src/spec/targets/riscv32imafc_unknown_nuttx_elf.rs

@@ -6,9 +6,9 @@ pub(crate) fn target() -> Target {
         llvm_target: "riscv32".into(),
         metadata: crate::spec::TargetMetadata {
             description: None,
-            tier: None,
+            tier: Some(3),
             host_tools: None,
-            std: None,
+            std: Some(true),
         },
         pointer_width: 32,
         arch: "riscv32".into(),

compiler/rustc_target/src/spec/targets/riscv32imc_unknown_nuttx_elf.rs

@@ -6,9 +6,9 @@ pub(crate) fn target() -> Target {
         llvm_target: "riscv32".into(),
         metadata: crate::spec::TargetMetadata {
             description: None,
-            tier: None,
+            tier: Some(3),
             host_tools: None,
-            std: None,
+            std: Some(true),
         },
         pointer_width: 32,
         arch: "riscv32".into(),

compiler/rustc_target/src/spec/targets/riscv64gc_unknown_nuttx_elf.rs

@@ -8,9 +8,9 @@ pub(crate) fn target() -> Target {
         data_layout: "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128".into(),
         metadata: crate::spec::TargetMetadata {
             description: None,
-            tier: None,
+            tier: Some(3),
             host_tools: None,
-            std: None,
+            std: Some(true),
         },
         llvm_target: "riscv64".into(),
         pointer_width: 64,

compiler/rustc_target/src/spec/targets/riscv64imac_unknown_nuttx_elf.rs

@@ -8,9 +8,9 @@ pub(crate) fn target() -> Target {
         data_layout: "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128".into(),
         metadata: crate::spec::TargetMetadata {
             description: None,
-            tier: None,
+            tier: Some(3),
             host_tools: None,
-            std: None,
+            std: Some(true),
         },
         llvm_target: "riscv64".into(),
         pointer_width: 64,

compiler/rustc_target/src/spec/targets/thumbv6m_nuttx_eabi.rs

@@ -7,9 +7,9 @@ pub(crate) fn target() -> Target {
         llvm_target: "thumbv6m-none-eabi".into(),
         metadata: crate::spec::TargetMetadata {
             description: None,
-            tier: None,
+            tier: Some(3),
             host_tools: None,
-            std: None,
+            std: Some(true),
         },
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".into(),
@@ -22,12 +22,9 @@ pub(crate) fn target() -> Target {
             llvm_floatabi: Some(FloatAbi::Soft),
             // The ARMv6-M architecture doesn't support unaligned loads/stores so we disable them
             // with +strict-align.
-            // Also force-enable 32-bit atomics, which allows the use of atomic load/store only.
-            // The resulting atomics are ABI incompatible with atomics backed by libatomic.
-            features: "+strict-align,+atomics-32".into(),
-            // There are no atomic CAS instructions available in the instruction set of the ARMv6-M
-            // architecture
-            atomic_cas: false,
+            // The ARMv6-M doesn't support hardware atomic operations, use atomic builtins instead.
+            features: "+strict-align".into(),
+            max_atomic_width: Some(32),
             ..base::thumb::opts()
         },
     }