rustbuild: allow configuring llvm version suffix

config.toml.example

@@ -82,6 +82,10 @@
 # passed to prefer linking to shared libraries.
 #link-shared = false
 
+# When building llvm, this configures what is being appended to the version.
+# If absent, we let the version as-is.
+#version-suffix = "-rust"
+
 # On MSVC you can compile LLVM with clang-cl, but the test suite doesn't pass
 # with clang-cl, so this is special in that it only compiles LLVM with clang-cl
 #clang-cl = '/path/to/clang-cl.exe'

src/bootstrap/config.rs

@@ -86,6 +86,7 @@ pub struct Config {
     pub llvm_targets: Option<String>,
     pub llvm_experimental_targets: String,
     pub llvm_link_jobs: Option<u32>,
+    pub llvm_version_suffix: Option<String>,
 
     pub lld_enabled: bool,
     pub lldb_enabled: bool,
@@ -256,6 +257,7 @@ struct Llvm {
     experimental_targets: Option<String>,
     link_jobs: Option<u32>,
     link_shared: Option<bool>,
+    version_suffix: Option<String>,
     clang_cl: Option<String>
 }
 
@@ -516,6 +518,7 @@ impl Config {
             config.llvm_experimental_targets = llvm.experimental_targets.clone()
                 .unwrap_or("WebAssembly;RISCV".to_string());
             config.llvm_link_jobs = llvm.link_jobs;
+            config.llvm_version_suffix = llvm.version_suffix.clone();
             config.llvm_clang_cl = llvm.clang_cl.clone();
         }
 

src/bootstrap/native.rs

@@ -239,6 +239,10 @@ impl Step for Llvm {
             cfg.define("LLVM_NATIVE_BUILD", builder.llvm_out(builder.config.build).join("build"));
         }
 
+        if let Some(ref suffix) = builder.config.llvm_version_suffix {
+            cfg.define("LLVM_VERSION_SUFFIX", suffix);
+        }
+
         if let Some(ref python) = builder.config.python {
             cfg.define("PYTHON_EXECUTABLE", python);
         }