Auto merge of #130179 - workingjubilee:rollup-l78cv44, r=workingjubilee

Rollup of 11 pull requests

Successful merges:

 - #128316 (Stabilize most of `io_error_more`)
 - #129473 (use  `download-ci-llvm=true` in the default compiler config)
 - #129529 (Add test to build crates used by r-a on stable)
 - #129981 (Remove `serialized_bitcode` from `LtoModuleCodegen`.)
 - #130094 (Inform the solver if evaluation is concurrent)
 - #130132 ([illumos] enable SIGSEGV handler to detect stack overflows)
 - #130146 (bootstrap `naked_asm!` for `compiler-builtins`)
 - #130149 (Helper function for formatting with `LifetimeSuggestionPosition`)
 - #130152 (adapt a test for llvm 20)
 - #130162 (bump download-ci-llvm-stamp)
 - #130164 (move some const fn out of the const_ptr_as_ref feature)

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

4 files changed, 10 insertions, 3 deletions

diff --git a/src/bootstrap/defaults/config.compiler.toml b/src/bootstrap/defaults/config.compiler.toml
index 789586b58f7..147939d2047 100644
--- a/src/bootstrap/defaults/config.compiler.toml
+++ b/src/bootstrap/defaults/config.compiler.toml
@@ -27,4 +27,5 @@ assertions = false
 # Enable warnings during the LLVM compilation (when LLVM is changed, causing a compilation)
 enable-warnings = true
 # Will download LLVM from CI if available on your platform.
-download-ci-llvm = "if-unchanged"
+# If you intend to modify `src/llvm-project`, use `"if-unchanged"` or `false` instead.
+download-ci-llvm = true
diff --git a/src/bootstrap/download-ci-llvm-stamp b/src/bootstrap/download-ci-llvm-stamp
index 90901530501..42cecbf5df9 100644
--- a/src/bootstrap/download-ci-llvm-stamp
+++ b/src/bootstrap/download-ci-llvm-stamp
@@ -1,4 +1,4 @@
 Change this file to make users of the `download-ci-llvm` configuration download
 a new version of LLVM from CI, even if the LLVM submodule hasn’t changed.
 
-Last change is for: https://github.com/rust-lang/rust/pull/129116
+Last change is for: https://github.com/rust-lang/rust/pull/129788
diff --git a/src/bootstrap/src/core/config/config.rs b/src/bootstrap/src/core/config/config.rs
index de861c42c4c..f509712730d 100644
--- a/src/bootstrap/src/core/config/config.rs
+++ b/src/bootstrap/src/core/config/config.rs
@@ -2766,7 +2766,8 @@ impl Config {
                     );
                 }
 
-                b
+                // If download-ci-llvm=true we also want to check that CI llvm is available
+                b && llvm::is_ci_llvm_available(self, asserts)
             }
             Some(StringOrBool::String(s)) if s == "if-unchanged" => if_unchanged(),
             Some(StringOrBool::String(other)) => {
diff --git a/src/bootstrap/src/utils/change_tracker.rs b/src/bootstrap/src/utils/change_tracker.rs
index 80ab09881fe..99bcc6e0787 100644
--- a/src/bootstrap/src/utils/change_tracker.rs
+++ b/src/bootstrap/src/utils/change_tracker.rs
@@ -250,4 +250,9 @@ pub const CONFIG_CHANGE_HISTORY: &[ChangeInfo] = &[
         severity: ChangeSeverity::Info,
         summary: "New option `llvm.enzyme` to control whether the llvm based autodiff tool (Enzyme) is built.",
     },
+    ChangeInfo {
+        change_id: 129473,
+        severity: ChangeSeverity::Warning,
+        summary: "`download-ci-llvm = true` now checks if CI llvm is available and has become the default for the compiler profile",
+    },
 ];