Auto merge of #94298 - Urgau:rustbuild-check-cfg, r=Mark-Simulacrum

Enable conditional compilation checking on the Rust codebase

This pull-request enable conditional compilation checking on every rust project build by the `bootstrap` tool.

To be more specific, this PR only enable well known names checking + extra names (bootstrap, parallel_compiler, ...).

r? `@Mark-Simulacrum`

compiler/rustc_data_structures/src/sorted_map/index_map.rs

@@ -152,6 +152,3 @@ impl<I: Idx, K, V> std::ops::Index<I> for SortedIndexMultiMap<I, K, V> {
  &self.items[idx].1
  }
 }
-
-#[cfg(tests)]
-mod tests;

library/core/src/mem/maybe_uninit.rs

@@ -817,6 +817,7 @@ impl<T> MaybeUninit<T> {
  /// ### Correct usage of this method:
  ///
  /// ```rust
+ /// # #![allow(unexpected_cfgs)]
  /// use std::mem::MaybeUninit;
  ///
  /// # unsafe extern "C" fn initialize_buffer(buf: *mut [u8; 1024]) { *buf = [0; 1024] }

library/std/src/os/windows/fs.rs

@@ -158,6 +158,7 @@ pub trait OpenOptionsExt {
  /// # Examples
  ///
  /// ```no_run
+ /// # #![allow(unexpected_cfgs)]
  /// # #[cfg(for_demonstration_only)]
  /// extern crate winapi;
  /// # mod winapi { pub const FILE_FLAG_DELETE_ON_CLOSE: u32 = 0x04000000; }
@@ -195,6 +196,7 @@ pub trait OpenOptionsExt {
  /// # Examples
  ///
  /// ```no_run
+ /// # #![allow(unexpected_cfgs)]
  /// # #[cfg(for_demonstration_only)]
  /// extern crate winapi;
  /// # mod winapi { pub const FILE_ATTRIBUTE_HIDDEN: u32 = 2; }
@@ -236,6 +238,7 @@ pub trait OpenOptionsExt {
  /// # Examples
  ///
  /// ```no_run
+ /// # #![allow(unexpected_cfgs)]
  /// # #[cfg(for_demonstration_only)]
  /// extern crate winapi;
  /// # mod winapi { pub const SECURITY_IDENTIFICATION: u32 = 0; }

src/bootstrap/builder.rs

@@ -26,6 +26,7 @@ use crate::run;
 use crate::test;
 use crate::tool::{self, SourceType};
 use crate::util::{self, add_dylib_path, add_link_lib_path, exe, libdir};
+use crate::EXTRA_CHECK_CFGS;
 use crate::{Build, CLang, DocTests, GitRepo, Mode};
 
 pub use crate::Compiler;
@@ -1095,6 +1096,33 @@ impl<'a> Builder<'a> {
  rustflags.arg("-Zunstable-options");
  }
 
+ // #[cfg(not(bootstrap)]
+ if stage != 0 {
+ // Enable cfg checking of cargo features
+ // FIXME: De-comment this when cargo beta get support for it
+ // cargo.arg("-Zcheck-cfg-features");
+
+ // Enable cfg checking of rustc well-known names
+ rustflags.arg("-Zunstable-options").arg("--check-cfg=names()");
+
+ // Add extra cfg not defined in rustc
+ for (restricted_mode, name, values) in EXTRA_CHECK_CFGS {
+ if *restricted_mode == None || *restricted_mode == Some(mode) {
+ // Creating a string of the values by concatenating each value:
+ // ',"tvos","watchos"' or '' (nothing) when there are no values
+ let values = match values {
+ Some(values) => values
+ .iter()
+ .map(|val| [",", "\"", val, "\""])
+ .flatten()
+ .collect::<String>(),
+ None => String::new(),
+ };
+ rustflags.arg(&format!("--check-cfg=values({name}{values})"));
+ }
+ }
+ }
+
  // FIXME: It might be better to use the same value for both `RUSTFLAGS` and `RUSTDOCFLAGS`,
  // but this breaks CI. At the very least, stage0 `rustdoc` needs `--cfg bootstrap`. See
  // #71458.

src/bootstrap/lib.rs

@@ -186,6 +186,34 @@ const LLVM_TOOLS: &[&str] = &[
 
 pub const VERSION: usize = 2;
 
+/// Extra --check-cfg to add when building
+/// (Mode restriction, config name, config values (if any))
+const EXTRA_CHECK_CFGS: &[(Option<Mode>, &'static str, Option<&[&'static str]>)] = &[
+ (None, "bootstrap", None),
+ (Some(Mode::Rustc), "parallel_compiler", None),
+ (Some(Mode::ToolRustc), "parallel_compiler", None),
+ (Some(Mode::Std), "miri", None),
+ (Some(Mode::Std), "stdarch_intel_sde", None),
+ (Some(Mode::Std), "no_fp_fmt_parse", None),
+ (Some(Mode::Std), "no_global_oom_handling", None),
+ (Some(Mode::Std), "freebsd12", None),
+ (Some(Mode::Std), "backtrace_in_libstd", None),
+ // FIXME: Used by rustfmt is their test but is invalid (neither cargo nor bootstrap ever set
+ // this config) should probably by removed or use a allow attribute.
+ (Some(Mode::ToolRustc), "release", None),
+ // FIXME: Used by stdarch in their test, should use a allow attribute instead.
+ (Some(Mode::Std), "dont_compile_me", None),
+ // FIXME: Used by serde_json, but we should not be triggering on external dependencies.
+ (Some(Mode::Rustc), "no_btreemap_remove_entry", None),
+ (Some(Mode::ToolRustc), "no_btreemap_remove_entry", None),
+ // FIXME: Used by crossbeam-utils, but we should not be triggering on external dependencies.
+ (Some(Mode::Rustc), "crossbeam_loom", None),
+ (Some(Mode::ToolRustc), "crossbeam_loom", None),
+ // FIXME: Used by proc-macro2, but we should not be triggering on external dependencies.
+ (Some(Mode::Rustc), "span_locations", None),
+ (Some(Mode::ToolRustc), "span_locations", None),
+];
+
 /// A structure representing a Rust compiler.
 ///
 /// Each compiler has a `stage` that it is associated with and a `host` that