Build support for no llvm

Author: bjorn3

src/bootstrap/config.rs

@@ -53,6 +53,7 @@ pub struct Config {
     pub profiler: bool,
 
     // llvm codegen options
+    pub llvm_enabled: bool,
     pub llvm_assertions: bool,
     pub llvm_optimize: bool,
     pub llvm_release_debuginfo: bool,
@@ -192,6 +193,7 @@ struct Install {
 #[derive(Deserialize, Default)]
 #[serde(deny_unknown_fields, rename_all = "kebab-case")]
 struct Llvm {
+    enabled: Option<bool>,
     ccache: Option<StringOrBool>,
     ninja: Option<bool>,
     assertions: Option<bool>,
@@ -265,6 +267,7 @@ struct TomlTarget {
 impl Config {
     pub fn parse(build: &str, file: Option<PathBuf>) -> Config {
         let mut config = Config::default();
+        config.llvm_enabled = true;
         config.llvm_optimize = true;
         config.use_jemalloc = true;
         config.backtrace = true;
@@ -345,6 +348,7 @@ impl Config {
                 Some(StringOrBool::Bool(false)) | None => {}
             }
             set(&mut config.ninja, llvm.ninja);
+            set(&mut config.llvm_enabled, llvm.enabled);
             set(&mut config.llvm_assertions, llvm.assertions);
             set(&mut config.llvm_optimize, llvm.optimize);
             set(&mut config.llvm_release_debuginfo, llvm.release_debuginfo);

src/bootstrap/config.toml.example

@@ -14,6 +14,10 @@
 # =============================================================================
 [llvm]
 
+# Indicates whether rustc will support compilation with LLVM
+# note: rustc does not compile without LLVM at the moment
+#enabled = true
+
 # Indicates whether the LLVM build is a Release or Debug build
 #optimize = true
 

src/bootstrap/lib.rs

@@ -429,6 +429,9 @@ impl Build {
         if self.config.use_jemalloc {
             features.push_str(" jemalloc");
         }
+        if self.config.llvm_enabled {
+            features.push_str(" llvm");
+        }
         features
     }
 

src/bootstrap/native.rs

@@ -56,6 +56,12 @@ impl Step for Llvm {
     fn run(self, builder: &Builder) {
         let build = builder.build;
         let target = self.target;
+
+        // If we're not compiling for LLVM bail out here.
+        if !build.config.llvm_enabled {
+            return;
+        }
+
         // If we're using a custom LLVM bail out here, but we can only use a
         // custom LLVM for the build triple.
         if let Some(config) = build.config.target_config.get(&target) {