Rollup merge of #137072 - Urgau:check-cfg-load-builtins-at-once, r=Noratrieb

Load all builtin targets at once instead of one by one in check-cfg

This PR adds a method on `rustc_target::Target` to load all the builtin targets at once, and then uses that method when constructing the `target_*` values in check-cfg instead of load loading each target one by one by their name, which requires a lookup and was more of a hack anyway.

This may give us some performance improvements as we won't need to do the lookup for the _currently_ 287 targets we have.

1 files changed, 13 insertions, 0 deletions

diff --git a/compiler/rustc_target/src/spec/mod.rs b/compiler/rustc_target/src/spec/mod.rs
index 794d6457cb7..f7e467b0c11 100644
--- a/compiler/rustc_target/src/spec/mod.rs
+++ b/compiler/rustc_target/src/spec/mod.rs
@@ -1658,6 +1658,14 @@ macro_rules! supported_targets {
             Some(t)
         }
 
+        fn load_all_builtins() -> impl Iterator<Item = Target> {
+            [
+                $( targets::$module::target, )+
+            ]
+            .into_iter()
+            .map(|f| f())
+        }
+
         #[cfg(test)]
         mod tests {
             // Cannot put this into a separate file without duplication, make an exception.
@@ -3360,6 +3368,11 @@ impl Target {
         }
     }
 
+    /// Load all built-in targets
+    pub fn builtins() -> impl Iterator<Item = Target> {
+        load_all_builtins()
+    }
+
     /// Search for a JSON file specifying the given target tuple.
     ///
     /// If none is found in `$RUST_TARGET_PATH`, look for a file called `target.json` inside the