Auto merge of #117813 - onur-ozkan:simplify-download-ci-llvm-option, r=Mark-Simulacrum

deprecate `if-available` value of `download-ci-llvm`

This PR deprecates the use of the `if-available` value for `download-ci-llvm` since `if-unchanged` serves the same purpose when no changes are detected. In cases where changes are present, it is assumed that compiling LLVM is acceptable (otherwise, why make changes there?).

This was probably missing in the #110087 issue before.

cc `@RalfJung`

8 files changed, 18 insertions, 19 deletions

diff --git a/config.example.toml b/config.example.toml
index e5df28a49af..170856bd97d 100644
--- a/config.example.toml
+++ b/config.example.toml
@@ -42,18 +42,15 @@ change-id = 116881
 # Unless you're developing for a target where Rust CI doesn't build a compiler
 # toolchain or changing LLVM locally, you probably want to leave this enabled.
 #
-# Set this to `"if-available"` if you are not sure whether you're on a tier 1 
-# target. All tier 1 targets are currently supported;
-#
-# We also currently only support this when building LLVM for the build triple.
-#
-# Set this to `"if-unchanged"` to only download if the llvm-project have not 
-# been modified. (If there are no changes or if built from tarball source, 
-# the logic is the same as "if-available")
+# Set this to `"if-unchanged"` to download only if the llvm-project has not
+# been modified. You can also use this if you are unsure whether you're on a
+# tier 1 target. All tier 1 targets are currently supported.
+
+# Currently, we only support this when building LLVM for the build triple.
 #
 # 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" { "if-available" } else { false }
+#download-ci-llvm = if rust.channel == "dev" { "if-unchanged" } else { false }
 
 # Indicates whether the LLVM build is a Release or Debug build
 #optimize = true
diff --git a/src/bootstrap/defaults/config.compiler.toml b/src/bootstrap/defaults/config.compiler.toml
index b98b13119e8..b27b524b873 100644
--- a/src/bootstrap/defaults/config.compiler.toml
+++ b/src/bootstrap/defaults/config.compiler.toml
@@ -17,4 +17,4 @@ lto = "off"
 
 [llvm]
 # Will download LLVM from CI if available on your platform.
-download-ci-llvm = "if-available"
+download-ci-llvm = "if-unchanged"
diff --git a/src/bootstrap/defaults/config.library.toml b/src/bootstrap/defaults/config.library.toml
index f362c4111f1..087544397f5 100644
--- a/src/bootstrap/defaults/config.library.toml
+++ b/src/bootstrap/defaults/config.library.toml
@@ -13,4 +13,4 @@ lto = "off"
 
 [llvm]
 # Will download LLVM from CI if available on your platform.
-download-ci-llvm = "if-available"
+download-ci-llvm = "if-unchanged"
diff --git a/src/bootstrap/defaults/config.tools.toml b/src/bootstrap/defaults/config.tools.toml
index 79424f28d27..6e6c3660027 100644
--- a/src/bootstrap/defaults/config.tools.toml
+++ b/src/bootstrap/defaults/config.tools.toml
@@ -21,4 +21,4 @@ compiler-docs = true
 
 [llvm]
 # Will download LLVM from CI if available on your platform.
-download-ci-llvm = "if-available"
+download-ci-llvm = "if-unchanged"
diff --git a/src/bootstrap/src/core/config/config.rs b/src/bootstrap/src/core/config/config.rs
index 0a9175aa3ea..fa8b0b20cec 100644
--- a/src/bootstrap/src/core/config/config.rs
+++ b/src/bootstrap/src/core/config/config.rs
@@ -2113,6 +2113,8 @@ impl Config {
         match download_ci_llvm {
             None => self.channel == "dev" && llvm::is_ci_llvm_available(&self, asserts),
             Some(StringOrBool::Bool(b)) => b,
+            // FIXME: "if-available" is deprecated. Remove this block later (around mid 2024)
+            // to not break builds between the recent-to-old checkouts.
             Some(StringOrBool::String(s)) if s == "if-available" => {
                 llvm::is_ci_llvm_available(&self, asserts)
             }
diff --git a/src/bootstrap/src/tests/config.rs b/src/bootstrap/src/tests/config.rs
index 59bd52a94dc..a8106ca8ff9 100644
--- a/src/bootstrap/src/tests/config.rs
+++ b/src/bootstrap/src/tests/config.rs
@@ -24,19 +24,19 @@ fn download_ci_llvm() {
     }
 
     let parse_llvm = |s| parse(s).llvm_from_ci;
-    let if_available = parse_llvm("llvm.download-ci-llvm = \"if-available\"");
+    let if_unchanged = parse_llvm("llvm.download-ci-llvm = \"if-unchanged\"");
 
     assert!(parse_llvm("llvm.download-ci-llvm = true"));
     assert!(!parse_llvm("llvm.download-ci-llvm = false"));
-    assert_eq!(parse_llvm(""), if_available);
-    assert_eq!(parse_llvm("rust.channel = \"dev\""), if_available);
+    assert_eq!(parse_llvm(""), if_unchanged);
+    assert_eq!(parse_llvm("rust.channel = \"dev\""), if_unchanged);
     assert!(!parse_llvm("rust.channel = \"stable\""));
     assert!(parse_llvm("build.build = \"x86_64-unknown-linux-gnu\""));
     assert!(parse_llvm(
-        "llvm.assertions = true \r\n build.build = \"x86_64-unknown-linux-gnu\" \r\n llvm.download-ci-llvm = \"if-available\""
+        "llvm.assertions = true \r\n build.build = \"x86_64-unknown-linux-gnu\" \r\n llvm.download-ci-llvm = \"if-unchanged\""
     ));
     assert!(!parse_llvm(
-        "llvm.assertions = true \r\n build.build = \"aarch64-apple-darwin\" \r\n llvm.download-ci-llvm = \"if-available\""
+        "llvm.assertions = true \r\n build.build = \"aarch64-apple-darwin\" \r\n llvm.download-ci-llvm = \"if-unchanged\""
     ));
 }
 
diff --git a/src/ci/run.sh b/src/ci/run.sh
index ce0dd6018af..fa786c6c7e7 100755
--- a/src/ci/run.sh
+++ b/src/ci/run.sh
@@ -145,7 +145,7 @@ else
   # LLVM continuously on at least some builders to ensure it works, though.
   # (And PGO is its own can of worms).
   if [ "$NO_DOWNLOAD_CI_LLVM" = "" ]; then
-    RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --set llvm.download-ci-llvm=if-available"
+    RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --set llvm.download-ci-llvm=if-unchanged"
   else
     # When building for CI we want to use the static C++ Standard library
     # included with LLVM, since a dynamic libstdcpp may not be available.
diff --git a/src/ci/scripts/install-clang.sh b/src/ci/scripts/install-clang.sh
index cbb4d5765ca..77164ed4117 100755
--- a/src/ci/scripts/install-clang.sh
+++ b/src/ci/scripts/install-clang.sh
@@ -58,7 +58,7 @@ elif isWindows && [[ ${CUSTOM_MINGW-0} -ne 1 ]]; then
         "${RUST_CONFIGURE_ARGS} --set llvm.clang-cl=$(pwd)/clang-rust/bin/clang-cl.exe"
 
     # Disable downloading CI LLVM on this builder;
-    # setting up clang-cl just above conflicts with the default if-available option.
+    # setting up clang-cl just above conflicts with the default if-unchanged option.
     ciCommandSetEnv NO_DOWNLOAD_CI_LLVM 1
 fi