From e136e02fd97ac5207f1a0d1edd276ef22a1d24c1 Mon Sep 17 00:00:00 2001
From: Tyler Mandry <tmandry@google.com>
Date: Fri, 26 Aug 2022 19:24:41 -0700
Subject: [PATCH 1/2] bootstrap: Add llvm-has-rust-patches target option

This is so you can check out an upstream commit in src/llvm-project and
have everything just work.
---
 config.toml.example     |  4 ++++
 src/bootstrap/config.rs |  3 +++
 src/bootstrap/lib.rs    | 12 +++++++-----
 3 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/config.toml.example b/config.toml.example
index b3284050f05..28ccc2c8f14 100644
--- a/config.toml.example
+++ b/config.toml.example
@@ -666,6 +666,10 @@ changelog-seen = 2
 # target.
 #llvm-config = <none> (path)
 
+# Override detection of whether this is a Rust-patched LLVM. This would be used
+# in conjunction with either an llvm-config or build.submodules = false.
+#llvm-has-rust-patches = if llvm-config { false } else { true }
+
 # Normally the build system can find LLVM's FileCheck utility, but if
 # not, you can specify an explicit file name for it.
 #llvm-filecheck = "/path/to/llvm-version/bin/FileCheck"
diff --git a/src/bootstrap/config.rs b/src/bootstrap/config.rs
index ea0f78e2a6b..f98f07b8eba 100644
--- a/src/bootstrap/config.rs
+++ b/src/bootstrap/config.rs
@@ -388,6 +388,7 @@ fn eq(&self, other: &&str) -> bool {
 pub struct Target {
     /// Some(path to llvm-config) if using an external LLVM.
     pub llvm_config: Option<PathBuf>,
+    pub llvm_has_rust_patches: Option<bool>,
     /// Some(path to FileCheck) if one was specified.
     pub llvm_filecheck: Option<PathBuf>,
     pub llvm_libunwind: Option<LlvmLibunwind>,
@@ -729,6 +730,7 @@ struct TomlTarget {
         default_linker: Option<PathBuf> = "default-linker",
         linker: Option<String> = "linker",
         llvm_config: Option<String> = "llvm-config",
+        llvm_has_rust_patches: Option<bool> = "llvm-has-rust-patches",
         llvm_filecheck: Option<String> = "llvm-filecheck",
         llvm_libunwind: Option<String> = "llvm-libunwind",
         android_ndk: Option<String> = "android-ndk",
@@ -1140,6 +1142,7 @@ pub fn parse(args: &[String]) -> Config {
                 if let Some(ref s) = cfg.llvm_config {
                     target.llvm_config = Some(config.src.join(s));
                 }
+                target.llvm_has_rust_patches = cfg.llvm_has_rust_patches;
                 if let Some(ref s) = cfg.llvm_filecheck {
                     target.llvm_filecheck = Some(config.src.join(s));
                 }
diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index cd421c249d8..751692b46f3 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -112,6 +112,7 @@
 use std::process::Command;
 use std::str;
 
+use config::Target;
 use filetime::FileTime;
 use once_cell::sync::OnceCell;
 
@@ -854,12 +855,13 @@ fn md_doc_out(&self, target: TargetSelection) -> Interned<PathBuf> {
     ///
     /// If no custom `llvm-config` was specified then Rust's llvm will be used.
     fn is_rust_llvm(&self, target: TargetSelection) -> bool {
-        if self.config.llvm_from_ci && target == self.config.build {
-            return true;
-        }
-
         match self.config.target_config.get(&target) {
-            Some(ref c) => c.llvm_config.is_none(),
+            Some(Target { llvm_has_rust_patches: Some(patched), .. }) => *patched,
+            Some(Target { llvm_config, .. }) => {
+                // If the user set llvm-config we assume Rust is not patched,
+                // but first check to see if it was configured by llvm-from-ci.
+                (self.config.llvm_from_ci && target == self.config.build) || llvm_config.is_none()
+            }
             None => true,
         }
     }

From 73958fdf14d965eac2148991af99f0e0ad0c97ad Mon Sep 17 00:00:00 2001
From: Tyler Mandry <tmandry@google.com>
Date: Fri, 26 Aug 2022 19:29:39 -0700
Subject: [PATCH 2/2] Ignore cargo target folder in src/bootstrap

Needed after changes in #97513.
---
 .gitignore | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.gitignore b/.gitignore
index a6625ac2ac4..79405e37775 100644
--- a/.gitignore
+++ b/.gitignore
@@ -45,6 +45,7 @@ no_llvm_build
 /dist/
 /unicode-downloads
 /target
+/src/bootstrap/target
 /src/tools/x/target
 # Created by default with `src/ci/docker/run.sh`
 /obj/