Allow comptime fns to call other comptime fns

Author: oli-obk

compiler/rustc_middle/src/hir/map.rs

@@ -321,7 +321,13 @@ impl<'tcx> TyCtxt<'tcx> {
             BodyOwnerKind::Closure if self.is_const_fn(def_id) => {
                 return self.hir_body_const_context(self.local_parent(local_def_id));
             }
-            BodyOwnerKind::Fn if self.is_const_fn(def_id) => ConstContext::ConstFn,
+            BodyOwnerKind::Fn if self.is_const_fn(def_id) => {
+                if matches!(self.constness(def_id), rustc_hir::Constness::Const { always: true }) {
+                    ConstContext::Const { inline: true }
+                } else {
+                    ConstContext::ConstFn
+                }
+            }
             BodyOwnerKind::Fn | BodyOwnerKind::Closure | BodyOwnerKind::GlobalAsm => return None,
         };
 

tests/ui/comptime/not_callable.rs

@@ -17,6 +17,6 @@ const fn bar() {
 
 #[rustc_comptime]
 fn baz() {
-    // TODO: Should be allowed
-    foo(); //~ ERROR: comptime fns can only be called at compile time
+    // Ok
+    foo();
 }

tests/ui/comptime/not_callable.stderr

@@ -10,11 +10,5 @@ error: comptime fns can only be called at compile time
 LL |     foo();
    |     ^^^^^
 
-error: comptime fns can only be called at compile time
-  --> $DIR/not_callable.rs:21:5
-   |
-LL |     foo();
-   |     ^^^^^
-
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors