Rollup merge of rust-lang#66498 - bjorn3:less_feature_flags, r=Dylan-DPC

Remove unused feature gates

I think many of the remaining unstable things can be easily be replaced with stable things. I have kept the `#![feature(nll)]` even though it is only necessary in `libstd`, to make regressions of it harder.

Author: Dylan-DPC

src/bootstrap/lib.rs

@@ -103,7 +103,6 @@
 //! More documentation can be found in each respective module below, and you can
 //! also check out the `src/bootstrap/README.md` file for more information.
 
-#![feature(core_intrinsics)]
 #![feature(drain_filter)]
 
 use std::cell::{Cell, RefCell};

src/librustc/lib.rs

@@ -27,7 +27,6 @@
 //! This API is completely unstable and subject to change.
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
-#![feature(arbitrary_self_types)]
 #![feature(bool_to_option)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
@@ -39,21 +38,15 @@
 #![feature(marker_trait_attr)]
 #![feature(extern_types)]
 #![feature(nll)]
-#![feature(optin_builtin_traits)]
 #![feature(option_expect_none)]
 #![feature(range_is_empty)]
 #![feature(specialization)]
-#![feature(unboxed_closures)]
-#![feature(thread_local)]
-#![feature(trace_macros)]
 #![feature(trusted_len)]
 #![feature(vec_remove_item)]
 #![feature(stmt_expr_attributes)]
-#![feature(integer_atomics)]
 #![feature(test)]
 #![feature(in_band_lifetimes)]
 #![feature(crate_visibility_modifier)]
-#![feature(log_syntax)]
 #![feature(associated_type_bounds)]
 #![feature(rustc_attrs)]
 #![feature(hash_raw_entry)]

src/librustc_codegen_llvm/lib.rs

@@ -6,18 +6,11 @@
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
 #![feature(bool_to_option)]
-#![feature(box_patterns)]
-#![feature(box_syntax)]
 #![feature(const_cstr_unchecked)]
 #![feature(crate_visibility_modifier)]
 #![feature(extern_types)]
 #![feature(in_band_lifetimes)]
-#![feature(libc)]
 #![feature(nll)]
-#![feature(optin_builtin_traits)]
-#![feature(concat_idents)]
-#![feature(link_args)]
-#![feature(static_nobundle)]
 #![feature(trusted_len)]
 #![recursion_limit = "256"]
 
@@ -196,7 +189,7 @@ unsafe impl Sync for LlvmCodegenBackend {}
 
 impl LlvmCodegenBackend {
     pub fn new() -> Box<dyn CodegenBackend> {
-        box LlvmCodegenBackend(())
+        Box::new(LlvmCodegenBackend(()))
     }
 }
 
@@ -245,7 +238,7 @@ impl CodegenBackend for LlvmCodegenBackend {
     }
 
     fn metadata_loader(&self) -> Box<MetadataLoaderDyn> {
-        box metadata::LlvmMetadataLoader
+        Box::new(metadata::LlvmMetadataLoader)
     }
 
     fn provide(&self, providers: &mut ty::query::Providers<'_>) {
@@ -262,12 +255,12 @@ impl CodegenBackend for LlvmCodegenBackend {
         metadata: EncodedMetadata,
         need_metadata_module: bool,
     ) -> Box<dyn Any> {
-        box rustc_codegen_ssa::base::codegen_crate(
+        Box::new(rustc_codegen_ssa::base::codegen_crate(
             LlvmCodegenBackend(()),
             tcx,
             metadata,
             need_metadata_module,
-        )
+        ))
     }
 
     fn join_codegen(

src/librustc_codegen_llvm/metadata.rs

@@ -22,10 +22,11 @@ impl MetadataLoader for LlvmMetadataLoader {
         // Use ArchiveRO for speed here, it's backed by LLVM and uses mmap
         // internally to read the file. We also avoid even using a memcpy by
         // just keeping the archive along while the metadata is in use.
-        let archive = ArchiveRO::open(filename).map(|ar| OwningRef::new(box ar)).map_err(|e| {
-            debug!("llvm didn't like `{}`: {}", filename.display(), e);
-            format!("failed to read rlib metadata in '{}': {}", filename.display(), e)
-        })?;
+        let archive =
+            ArchiveRO::open(filename).map(|ar| OwningRef::new(Box::new(ar))).map_err(|e| {
+                debug!("llvm didn't like `{}`: {}", filename.display(), e);
+                format!("failed to read rlib metadata in '{}': {}", filename.display(), e)
+            })?;
         let buf: OwningRef<_, [u8]> = archive.try_map(|ar| {
             ar.iter()
                 .filter_map(|s| s.ok())
@@ -44,9 +45,10 @@ impl MetadataLoader for LlvmMetadataLoader {
             let buf = path_to_c_string(filename);
             let mb = llvm::LLVMRustCreateMemoryBufferWithContentsOfFile(buf.as_ptr())
                 .ok_or_else(|| format!("error reading library: '{}'", filename.display()))?;
-            let of = ObjectFile::new(mb).map(|of| OwningRef::new(box of)).ok_or_else(|| {
-                format!("provided path not an object file: '{}'", filename.display())
-            })?;
+            let of =
+                ObjectFile::new(mb).map(|of| OwningRef::new(Box::new(of))).ok_or_else(|| {
+                    format!("provided path not an object file: '{}'", filename.display())
+                })?;
             let buf = of.try_map(|of| search_meta_section(of, target, filename))?;
             Ok(rustc_erase_owner!(buf))
         }

src/librustc_codegen_ssa/lib.rs

@@ -1,10 +1,6 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
 #![feature(bool_to_option)]
 #![feature(box_patterns)]
-#![feature(box_syntax)]
-#![feature(core_intrinsics)]
-#![feature(libc)]
-#![feature(stmt_expr_attributes)]
 #![feature(try_blocks)]
 #![feature(in_band_lifetimes)]
 #![feature(nll)]

src/librustc_codegen_utils/lib.rs

@@ -3,10 +3,6 @@
 //! This API is completely unstable and subject to change.
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
-#![feature(arbitrary_self_types)]
-#![feature(box_patterns)]
-#![feature(box_syntax)]
-#![feature(core_intrinsics)]
 #![feature(never_type)]
 #![feature(nll)]
 #![feature(in_band_lifetimes)]

src/librustc_data_structures/lib.rs

@@ -12,19 +12,16 @@
 #![feature(generators)]
 #![feature(generator_trait)]
 #![feature(fn_traits)]
-#![feature(unsize)]
 #![feature(specialization)]
 #![feature(optin_builtin_traits)]
 #![feature(nll)]
 #![feature(allow_internal_unstable)]
 #![feature(hash_raw_entry)]
 #![feature(stmt_expr_attributes)]
 #![feature(core_intrinsics)]
-#![feature(integer_atomics)]
 #![feature(test)]
 #![feature(associated_type_bounds)]
 #![feature(thread_id_value)]
-#![cfg_attr(unix, feature(libc))]
 #![allow(rustc::default_hash_types)]
 
 #[macro_use]

src/librustc_driver/lib.rs

@@ -5,12 +5,7 @@
 //! This API is completely unstable and subject to change.
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
-#![feature(box_syntax)]
-#![cfg_attr(unix, feature(libc))]
 #![feature(nll)]
-#![feature(set_stdio)]
-#![feature(no_debug)]
-#![feature(integer_atomics)]
 #![recursion_limit = "256"]
 
 pub extern crate getopts;

src/librustc_errors/lib.rs

@@ -4,9 +4,7 @@
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
 #![feature(crate_visibility_modifier)]
-#![cfg_attr(unix, feature(libc))]
 #![feature(nll)]
-#![feature(optin_builtin_traits)]
 
 pub use emitter::ColorConfig;
 

src/librustc_incremental/lib.rs

@@ -3,7 +3,6 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
 #![feature(in_band_lifetimes)]
 #![feature(nll)]
-#![feature(specialization)]
 #![recursion_limit = "256"]
 
 #[macro_use]