From 7e0eb3bc6df7199c908eb095ff63635e4c2239b0 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Tue, 24 Jun 2025 19:32:29 +0000
Subject: [PATCH] Taint body on invalid call ABI

(cherry picked from commit e776065164f22872e8cadf5bc5e47352c27982dc)
---
 compiler/rustc_hir_typeck/src/callee.rs   | 11 ++++++++++-
 tests/ui/abi/invalid-call-abi-ctfe.rs     | 14 ++++++++++++++
 tests/ui/abi/invalid-call-abi-ctfe.stderr |  9 +++++++++
 3 files changed, 33 insertions(+), 1 deletion(-)
 create mode 100644 tests/ui/abi/invalid-call-abi-ctfe.rs
 create mode 100644 tests/ui/abi/invalid-call-abi-ctfe.stderr

diff --git a/compiler/rustc_hir_typeck/src/callee.rs b/compiler/rustc_hir_typeck/src/callee.rs
index 7a3647df0c40..f790c51f8f19 100644
--- a/compiler/rustc_hir_typeck/src/callee.rs
+++ b/compiler/rustc_hir_typeck/src/callee.rs
@@ -156,7 +156,16 @@ pub(crate) fn check_expr_call(
     pub(crate) fn check_call_abi(&self, abi: ExternAbi, span: Span) {
         let canon_abi = match AbiMap::from_target(&self.sess().target).canonize_abi(abi, false) {
             AbiMapping::Direct(canon_abi) | AbiMapping::Deprecated(canon_abi) => canon_abi,
-            AbiMapping::Invalid => return,
+            AbiMapping::Invalid => {
+                // This should be reported elsewhere, but we want to taint this body
+                // so that we don't try to evaluate calls to ABIs that are invalid.
+                let guar = self.dcx().span_delayed_bug(
+                    span,
+                    format!("invalid abi for platform should have reported an error: {abi}"),
+                );
+                self.set_tainted_by_errors(guar);
+                return;
+            }
         };
 
         let valid = match canon_abi {
diff --git a/tests/ui/abi/invalid-call-abi-ctfe.rs b/tests/ui/abi/invalid-call-abi-ctfe.rs
new file mode 100644
index 000000000000..c72b72c152cd
--- /dev/null
+++ b/tests/ui/abi/invalid-call-abi-ctfe.rs
@@ -0,0 +1,14 @@
+// Fix for #142969 where an invalid ABI in a signature still had its call ABI computed
+// because CTFE tried to evaluate it, despite previous errors during AST-to-HIR lowering.
+
+#![feature(rustc_attrs)]
+
+const extern "rust-invalid" fn foo() {
+    //~^ ERROR `"rust-invalid"` is not a supported ABI for the current target
+    panic!()
+}
+
+const _: () = foo();
+
+
+fn main() {}
diff --git a/tests/ui/abi/invalid-call-abi-ctfe.stderr b/tests/ui/abi/invalid-call-abi-ctfe.stderr
new file mode 100644
index 000000000000..df4727a28023
--- /dev/null
+++ b/tests/ui/abi/invalid-call-abi-ctfe.stderr
@@ -0,0 +1,9 @@
+error[E0570]: `"rust-invalid"` is not a supported ABI for the current target
+  --> $DIR/invalid-call-abi-ctfe.rs:6:1
+   |
+LL | const extern "rust-invalid" fn foo() {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0570`.