consistency check for self-contained linking components CLI options

emit an error if components are both enabled and disabled on the CLI

Author: lqd

compiler/rustc_session/src/config.rs

@@ -306,6 +306,17 @@ impl LinkSelfContained {
     pub fn is_linker_disabled(&self) -> bool {
         self.disabled_components.contains(LinkSelfContainedComponents::LINKER)
     }
+
+    /// Returns CLI inconsistencies to emit errors: individual components were both enabled and
+    /// disabled.
+    fn check_consistency(&self) -> Option<LinkSelfContainedComponents> {
+        if self.explicitly_set.is_some() {
+            None
+        } else {
+            let common = self.enabled_components.intersection(self.disabled_components);
+            if common.is_empty() { None } else { Some(common) }
+        }
+    }
 }
 
 /// Used with `-Z assert-incr-state`.
@@ -2766,6 +2777,19 @@ pub fn build_session_options(
         }
     }
 
+    // Check `-C link-self-contained` for consistency: individual components cannot be both enabled
+    // and disabled at the same time.
+    if let Some(erroneous_components) = cg.link_self_contained.check_consistency() {
+        let names: String = erroneous_components
+            .into_iter()
+            .map(|c| c.as_str().unwrap())
+            .intersperse(", ")
+            .collect();
+        handler.early_error(format!(
+            "some `-C link-self-contained` components were both enabled and disabled: {names}"
+        ));
+    }
+
     let prints = collect_print_requests(handler, &mut cg, &mut unstable_opts, matches);
 
     let cg = cg;

compiler/rustc_session/src/lib.rs

@@ -6,6 +6,7 @@
 #![feature(option_get_or_insert_default)]
 #![feature(rustc_attrs)]
 #![feature(map_many_mut)]
+#![feature(iter_intersperse)]
 #![recursion_limit = "256"]
 #![allow(rustc::potential_query_instability)]
 #![deny(rustc::untranslatable_diagnostic)]

compiler/rustc_target/src/spec/mod.rs

@@ -670,7 +670,7 @@ impl LinkSelfContainedComponents {
     /// Return the component's name.
     ///
     /// Returns `None` if the bitflags aren't a singular component (but a mix of multiple flags).
-    fn as_str(self) -> Option<&'static str> {
+    pub fn as_str(self) -> Option<&'static str> {
         Some(match self {
             LinkSelfContainedComponents::CRT_OBJECTS => "crto",
             LinkSelfContainedComponents::LIBC => "libc",