Initial support for dynamically linked crates

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -84,6 +84,8 @@ struct AstValidator<'a> {
 
     lint_node_id: NodeId,
 
+    is_sdylib_interface: bool,
+
     lint_buffer: &'a mut LintBuffer,
 }
 
@@ -952,7 +954,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                 self.check_defaultness(item.span, *defaultness);
 
                 let is_intrinsic = item.attrs.iter().any(|a| a.has_name(sym::rustc_intrinsic));
-                if body.is_none() && !is_intrinsic {
+                if body.is_none() && !is_intrinsic && !self.is_sdylib_interface {
                     self.dcx().emit_err(errors::FnWithoutBody {
                         span: item.span,
                         replace_span: self.ending_semi_or_hi(item.span),
@@ -1441,7 +1443,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                     });
                 }
                 AssocItemKind::Fn(box Fn { body, .. }) => {
-                    if body.is_none() {
+                    if body.is_none() && !self.is_sdylib_interface {
                         self.dcx().emit_err(errors::AssocFnWithoutBody {
                             span: item.span,
                             replace_span: self.ending_semi_or_hi(item.span),
@@ -1689,6 +1691,7 @@ pub fn check_crate(
     sess: &Session,
     features: &Features,
     krate: &Crate,
+    is_sdylib_interface: bool,
     lints: &mut LintBuffer,
 ) -> bool {
     let mut validator = AstValidator {
@@ -1701,6 +1704,7 @@ pub fn check_crate(
         disallow_tilde_const: Some(TildeConstReason::Item),
         extern_mod_safety: None,
         lint_node_id: CRATE_NODE_ID,
+        is_sdylib_interface,
         lint_buffer: lints,
     };
     visit::walk_crate(&mut validator, krate);