Rollup merge of rust-lang#72146 - Mark-Simulacrum:separate-std-asserts, r=alexcrichton

Provide separate option for std debug asserts

On local one-off benchmarking of libcore metadata-only, debug asserts in std are a significant hit (15s to 20s). Provide an option for compiler developers to disable them. A build with a nightly compiler is around 10s, for reference.

Author: Dylan-DPC

config.toml.example

@@ -314,6 +314,10 @@
 # library.
 #debug-assertions = false
 
+# Whether or not debug assertions are enabled for the standard library.
+# Overrides the `debug-assertions` option, if defined.
+#debug-assertions-std = false
+
 # Debuginfo level for most of Rust code, corresponds to the `-C debuginfo=N` option of `rustc`.
 # `0` - no debug info
 # `1` - line tables only

src/bootstrap/builder.rs

@@ -915,7 +915,14 @@ impl<'a> Builder<'a> {
             .env("RUSTC", self.out.join("bootstrap/debug/rustc"))
             .env("RUSTC_REAL", self.rustc(compiler))
             .env("RUSTC_STAGE", stage.to_string())
-            .env("RUSTC_DEBUG_ASSERTIONS", self.config.rust_debug_assertions.to_string())
+            .env(
+                "RUSTC_DEBUG_ASSERTIONS",
+                if mode == Mode::Std {
+                    self.config.rust_debug_assertions_std.to_string()
+                } else {
+                    self.config.rust_debug_assertions.to_string()
+                },
+            )
             .env("RUSTC_SYSROOT", &sysroot)
             .env("RUSTC_LIBDIR", &libdir)
             .env("RUSTDOC", self.out.join("bootstrap/debug/rustdoc"))

src/bootstrap/config.rs

@@ -97,6 +97,7 @@ pub struct Config {
     pub rust_codegen_units: Option<u32>,
     pub rust_codegen_units_std: Option<u32>,
     pub rust_debug_assertions: bool,
+    pub rust_debug_assertions_std: bool,
     pub rust_debuginfo_level_rustc: u32,
     pub rust_debuginfo_level_std: u32,
     pub rust_debuginfo_level_tools: u32,
@@ -314,6 +315,7 @@ struct Rust {
     codegen_units: Option<u32>,
     codegen_units_std: Option<u32>,
     debug_assertions: Option<bool>,
+    debug_assertions_std: Option<bool>,
     debuginfo_level: Option<u32>,
     debuginfo_level_rustc: Option<u32>,
     debuginfo_level_std: Option<u32>,
@@ -518,6 +520,7 @@ impl Config {
         let mut llvm_assertions = None;
         let mut debug = None;
         let mut debug_assertions = None;
+        let mut debug_assertions_std = None;
         let mut debuginfo_level = None;
         let mut debuginfo_level_rustc = None;
         let mut debuginfo_level_std = None;
@@ -560,6 +563,7 @@ impl Config {
         if let Some(ref rust) = toml.rust {
             debug = rust.debug;
             debug_assertions = rust.debug_assertions;
+            debug_assertions_std = rust.debug_assertions_std;
             debuginfo_level = rust.debuginfo_level;
             debuginfo_level_rustc = rust.debuginfo_level_rustc;
             debuginfo_level_std = rust.debuginfo_level_std;
@@ -658,6 +662,8 @@ impl Config {
 
         let default = debug == Some(true);
         config.rust_debug_assertions = debug_assertions.unwrap_or(default);
+        config.rust_debug_assertions_std =
+            debug_assertions_std.unwrap_or(config.rust_debug_assertions);
 
         let with_defaults = |debuginfo_level_specific: Option<u32>| {
             debuginfo_level_specific.or(debuginfo_level).unwrap_or(if debug == Some(true) {