change download-ci-llvm default from if-unchanged to true

config.example.toml

@@ -53,7 +53,7 @@
 #
 # Note that many of the LLVM options are not currently supported for
 # downloading. Currently only the "assertions" option can be toggled.
-#download-ci-llvm = if rust.channel == "dev" || rust.download-rustc != false { "if-unchanged" } else { false }
+#download-ci-llvm = true
 
 # Indicates whether the LLVM build is a Release or Debug build
 #optimize = true

src/bootstrap/src/core/config/config.rs

@@ -2738,6 +2738,8 @@ impl Config {
         download_ci_llvm: Option<StringOrBool>,
         asserts: bool,
     ) -> bool {
+        let download_ci_llvm = download_ci_llvm.unwrap_or(StringOrBool::Bool(true));
+
         let if_unchanged = || {
             if self.rust_info.is_from_tarball() {
                 // Git is needed for running "if-unchanged" logic.
@@ -2761,10 +2763,7 @@ impl Config {
         };
 
         match download_ci_llvm {
-            None => {
-                (self.channel == "dev" || self.download_rustc_commit.is_some()) && if_unchanged()
-            }
-            Some(StringOrBool::Bool(b)) => {
+            StringOrBool::Bool(b) => {
                 if !b && self.download_rustc_commit.is_some() {
                     panic!(
                         "`llvm.download-ci-llvm` cannot be set to `false` if `rust.download-rustc` is set to `true` or `if-unchanged`."
@@ -2774,8 +2773,8 @@ impl Config {
                 // 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)) => {
+            StringOrBool::String(s) if s == "if-unchanged" => if_unchanged(),
+            StringOrBool::String(other) => {
                 panic!("unrecognized option for download-ci-llvm: {:?}", other)
             }
         }

src/bootstrap/src/core/config/tests.rs

@@ -32,7 +32,7 @@ fn download_ci_llvm() {
     assert!(!parse_llvm("llvm.download-ci-llvm = false"));
     assert_eq!(parse_llvm(""), if_unchanged);
     assert_eq!(parse_llvm("rust.channel = \"dev\""), if_unchanged);
-    assert!(!parse_llvm("rust.channel = \"stable\""));
+    assert!(parse_llvm("rust.channel = \"stable\""));
     assert_eq!(parse_llvm("build.build = \"x86_64-unknown-linux-gnu\""), if_unchanged);
     assert_eq!(
         parse_llvm(

src/bootstrap/src/utils/change_tracker.rs

@@ -265,4 +265,9 @@ pub const CONFIG_CHANGE_HISTORY: &[ChangeInfo] = &[
         severity: ChangeSeverity::Info,
         summary: "New option `dist.vendor` added to control whether bootstrap should vendor dependencies for dist tarball.",
     },
+    ChangeInfo {
+        change_id: 130529,
+        severity: ChangeSeverity::Info,
+        summary: "If `llvm.download-ci-llvm` is not defined, it defaults to `true`.",
+    },
 ];