Enable varargs support for AAPCS calling convention

This is the default calling convention for ARM - it is used for extern "C",
therefore it supports varargs.

2 files changed, 3 insertions, 2 deletions

diff --git a/compiler/rustc_hir_analysis/src/lib.rs b/compiler/rustc_hir_analysis/src/lib.rs
index b0f333b79ca..ef788935efb 100644
--- a/compiler/rustc_hir_analysis/src/lib.rs
+++ b/compiler/rustc_hir_analysis/src/lib.rs
@@ -117,7 +117,7 @@ use rustc_hir::def::DefKind;
 fluent_messages! { "../messages.ftl" }
 
 fn require_c_abi_if_c_variadic(tcx: TyCtxt<'_>, decl: &hir::FnDecl<'_>, abi: Abi, span: Span) {
-    const CONVENTIONS_UNSTABLE: &str = "`C`, `cdecl`, `win64`, `sysv64` or `efiapi`";
+    const CONVENTIONS_UNSTABLE: &str = "`C`, `cdecl`, `aapcs`, `win64`, `sysv64` or `efiapi`";
     const CONVENTIONS_STABLE: &str = "`C` or `cdecl`";
     const UNSTABLE_EXPLAIN: &str =
         "using calling conventions other than `C` or `cdecl` for varargs functions is unstable";
diff --git a/compiler/rustc_target/src/spec/abi.rs b/compiler/rustc_target/src/spec/abi.rs
index 956a5cb5c2f..a99cccd42c4 100644
--- a/compiler/rustc_target/src/spec/abi.rs
+++ b/compiler/rustc_target/src/spec/abi.rs
@@ -68,7 +68,7 @@ pub enum Abi {
 impl Abi {
     pub fn supports_varargs(self) -> bool {
         // * C and Cdecl obviously support varargs.
-        // * C can be based on SysV64 or Win64, so they must support varargs.
+        // * C can be based on Aapcs, SysV64 or Win64, so they must support varargs.
         // * EfiApi is based on Win64 or C, so it also supports it.
         //
         // * Stdcall does not, because it would be impossible for the callee to clean
@@ -79,6 +79,7 @@ impl Abi {
         match self {
             Self::C { .. }
             | Self::Cdecl { .. }
+            | Self::Aapcs { .. }
             | Self::Win64 { .. }
             | Self::SysV64 { .. }
             | Self::EfiApi => true,