fix(host-config): fix panic when cross-compiling with host-config

src/cargo/core/compiler/compilation.rs

@@ -144,18 +144,25 @@ impl<'gctx> Compilation<'gctx> {
         let primary_rustc_process = bcx.build_config.primary_unit_rustc.clone();
         let rustc_workspace_wrapper_process = bcx.rustc().workspace_process();
         let host = bcx.host_triple().to_string();
+
+        // When `target-applies-to-host=false`, and without `--target`,
+        // there will be only `CompileKind::Host` in requested_kinds.
+        // Need to insert target config explicitly for target-applies-to-host=false
+        // to find the correct configs.
+        let insert_explicit_host_runner = !bcx.gctx.target_applies_to_host()?
+            && bcx
+                .build_config
+                .requested_kinds
+                .iter()
+                .any(CompileKind::is_host);
         let mut runners = bcx
             .build_config
             .requested_kinds
             .iter()
             .chain(Some(&CompileKind::Host))
             .map(|kind| Ok((*kind, target_runner(bcx, *kind)?)))
             .collect::<CargoResult<HashMap<_, _>>>()?;
-        if !bcx.gctx.target_applies_to_host()? {
-            // When `target-applies-to-host=false`, and without `--target`,
-            // there will be only `CompileKind::Host` in requested_kinds.
-            // Need to insert target config explicitly for target-applies-to-host=false
-            // to find the correct configs.
+        if insert_explicit_host_runner {
             let kind = explicit_host_kind(&host);
             runners.insert(kind, target_runner(bcx, kind)?);
         }
@@ -167,8 +174,7 @@ impl<'gctx> Compilation<'gctx> {
             .chain(Some(&CompileKind::Host))
             .map(|kind| Ok((*kind, target_linker(bcx, *kind)?)))
             .collect::<CargoResult<HashMap<_, _>>>()?;
-        if !bcx.gctx.target_applies_to_host()? {
-            // See above reason in runner why we do this.
+        if insert_explicit_host_runner {
             let kind = explicit_host_kind(&host);
             linkers.insert(kind, target_linker(bcx, kind)?);
         }

tests/testsuite/cross_compile.rs

@@ -1339,6 +1339,7 @@ fn host_linker_does_not_apply_to_binary_build() {
     // host.linker should not be applied but target.linker
     p.cargo("build -Z target-applies-to-host -Z host-config")
         .masquerade_as_nightly_cargo(&["target-applies-to-host", "host-config"])
+        .env("CARGO_TARGET_APPLIES_TO_HOST", "false")
         .with_status(101)
         // Need to omit some MSVC-specific diagnostics
         // because rustc prints extra stuff when linker was not found.
@@ -1352,3 +1353,20 @@ fn host_linker_does_not_apply_to_binary_build() {
 "#]])
         .run();
 }
+
+#[cargo_test]
+fn cross_with_host_config() {
+    if cross_compile_disabled() {
+        return;
+    }
+
+    let target = cross_compile::alternate();
+
+    let p = project().file("src/main.rs", "fn main() {}").build();
+
+    p.cargo("build -Z target-applies-to-host -Z host-config --target")
+        .arg(&target)
+        .masquerade_as_nightly_cargo(&["target-applies-to-host", "host-config"])
+        .with_status(0)
+        .run();
+}