1 files changed, 108 insertions, 0 deletions
diff --git a/src/tools/rust-analyzer/crates/ide-completion/src/completions/extern_abi.rs b/src/tools/rust-analyzer/crates/ide-completion/src/completions/extern_abi.rs
new file mode 100644
index 000000000..4e89ef696
--- /dev/null
+++ b/src/tools/rust-analyzer/crates/ide-completion/src/completions/extern_abi.rs
@@ -0,0 +1,108 @@
+//! Completes function abi strings.
+use syntax::{
+    ast::{self, IsString},
+    AstNode, AstToken,
+};
+
+use crate::{
+    completions::Completions, context::CompletionContext, CompletionItem, CompletionItemKind,
+};
+
+// Most of these are feature gated, we should filter/add feature gate completions once we have them.
+const SUPPORTED_CALLING_CONVENTIONS: &[&str] = &[
+    "Rust",
+    "C",
+    "C-unwind",
+    "cdecl",
+    "stdcall",
+    "stdcall-unwind",
+    "fastcall",
+    "vectorcall",
+    "thiscall",
+    "thiscall-unwind",
+    "aapcs",
+    "win64",
+    "sysv64",
+    "ptx-kernel",
+    "msp430-interrupt",
+    "x86-interrupt",
+    "amdgpu-kernel",
+    "efiapi",
+    "avr-interrupt",
+    "avr-non-blocking-interrupt",
+    "C-cmse-nonsecure-call",
+    "wasm",
+    "system",
+    "system-unwind",
+    "rust-intrinsic",
+    "rust-call",
+    "platform-intrinsic",
+    "unadjusted",
+];
+
+pub(crate) fn complete_extern_abi(
+    acc: &mut Completions,
+    _ctx: &CompletionContext<'_>,
+    expanded: &ast::String,
+) -> Option<()> {
+    if !expanded.syntax().parent().map_or(false, |it| ast::Abi::can_cast(it.kind())) {
+        return None;
+    }
+    let abi_str = expanded;
+    let source_range = abi_str.text_range_between_quotes()?;
+    for &abi in SUPPORTED_CALLING_CONVENTIONS {
+        CompletionItem::new(CompletionItemKind::Keyword, source_range, abi).add_to(acc);
+    }
+    Some(())
+}
+
+#[cfg(test)]
+mod tests {
+    use expect_test::{expect, Expect};
+
+    use crate::tests::{check_edit, completion_list_no_kw};
+
+    fn check(ra_fixture: &str, expect: Expect) {
+        let actual = completion_list_no_kw(ra_fixture);
+        expect.assert_eq(&actual);
+    }
+
+    #[test]
+    fn only_completes_in_string_literals() {
+        check(
+            r#"
+$0 fn foo {}
+"#,
+            expect![[]],
+        );
+    }
+
+    #[test]
+    fn requires_extern_prefix() {
+        check(
+            r#"
+"$0" fn foo {}
+"#,
+            expect![[]],
+        );
+    }
+
+    #[test]
+    fn works() {
+        check(
+            r#"
+extern "$0" fn foo {}
+"#,
+            expect![[]],
+        );
+        check_edit(
+            "Rust",
+            r#"
+extern "$0" fn foo {}
+"#,
+            r#"
+extern "Rust" fn foo {}
+"#,
+        );
+    }
+}