Rollup merge of #132653 - BoxyUwU:const_arg_stmt_mac_call, r=compiler-errors

Don't use `maybe_unwrap_block` when checking for macro calls in a block expr

Fixes #131915

Using `maybe_unwrap_block` to determine if we are looking at a `{ mac_call!{} }` will fail sometimes as `mac_call!{}` could be a `StmtKind::MacCall` not a `StmtKind::Expr`. This caused the def collector to think that `{ mac_call!{} }` was a non-trivial const argument and create a definition for it even though it should not.

r? `@compiler-errors`  cc `@camelid`

6 files changed, 466 insertions, 36 deletions

diff --git a/compiler/rustc_ast/src/ast.rs b/compiler/rustc_ast/src/ast.rs
index 997c44cffff..5f71fb97d76 100644
--- a/compiler/rustc_ast/src/ast.rs
+++ b/compiler/rustc_ast/src/ast.rs
@@ -1194,7 +1194,7 @@ impl Expr {
     ///
     /// Does not ensure that the path resolves to a const param, the caller should check this.
     pub fn is_potential_trivial_const_arg(&self, strip_identity_block: bool) -> bool {
-        let this = if strip_identity_block { self.maybe_unwrap_block().1 } else { self };
+        let this = if strip_identity_block { self.maybe_unwrap_block() } else { self };
 
         if let ExprKind::Path(None, path) = &this.kind
             && path.is_potential_trivial_const_arg()
@@ -1206,14 +1206,41 @@ impl Expr {
     }
 
     /// Returns an expression with (when possible) *one* outter brace removed
-    pub fn maybe_unwrap_block(&self) -> (bool, &Expr) {
+    pub fn maybe_unwrap_block(&self) -> &Expr {
         if let ExprKind::Block(block, None) = &self.kind
             && let [stmt] = block.stmts.as_slice()
             && let StmtKind::Expr(expr) = &stmt.kind
         {
-            (true, expr)
+            expr
         } else {
-            (false, self)
+            self
+        }
+    }
+
+    /// Determines whether this expression is a macro call optionally wrapped in braces . If
+    /// `already_stripped_block` is set then we do not attempt to peel off a layer of braces.
+    ///
+    /// Returns the [`NodeId`] of the macro call and whether a layer of braces has been peeled
+    /// either before, or part of, this function.
+    pub fn optionally_braced_mac_call(
+        &self,
+        already_stripped_block: bool,
+    ) -> Option<(bool, NodeId)> {
+        match &self.kind {
+            ExprKind::Block(block, None)
+                if let [stmt] = &*block.stmts
+                    && !already_stripped_block =>
+            {
+                match &stmt.kind {
+                    StmtKind::MacCall(_) => Some((true, stmt.id)),
+                    StmtKind::Expr(expr) if let ExprKind::MacCall(_) = &expr.kind => {
+                        Some((true, expr.id))
+                    }
+                    _ => None,
+                }
+            }
+            ExprKind::MacCall(_) => Some((already_stripped_block, self.id)),
+            _ => None,
         }
     }
 
diff --git a/compiler/rustc_resolve/src/def_collector.rs b/compiler/rustc_resolve/src/def_collector.rs
index a825458dc89..bf27b767a49 100644
--- a/compiler/rustc_resolve/src/def_collector.rs
+++ b/compiler/rustc_resolve/src/def_collector.rs
@@ -130,18 +130,16 @@ impl<'a, 'ra, 'tcx> DefCollector<'a, 'ra, 'tcx> {
         &self,
         anon_const: &'a AnonConst,
     ) -> Option<(PendingAnonConstInfo, NodeId)> {
-        let (block_was_stripped, expr) = anon_const.value.maybe_unwrap_block();
-        match expr {
-            Expr { kind: ExprKind::MacCall(..), id, .. } => Some((
+        anon_const.value.optionally_braced_mac_call(false).map(|(block_was_stripped, id)| {
+            (
                 PendingAnonConstInfo {
                     id: anon_const.id,
                     span: anon_const.value.span,
                     block_was_stripped,
                 },
-                *id,
-            )),
-            _ => None,
-        }
+                id,
+            )
+        })
     }
 
     /// Determines whether the expression `const_arg_sub_expr` is a simple macro call, sometimes
@@ -161,18 +159,11 @@ impl<'a, 'ra, 'tcx> DefCollector<'a, 'ra, 'tcx> {
             panic!("Checking expr is trivial macro call without having entered anon const: `{const_arg_sub_expr:?}`"),
         );
 
-        let (block_was_stripped, expr) = if pending_anon.block_was_stripped {
-            (true, const_arg_sub_expr)
-        } else {
-            const_arg_sub_expr.maybe_unwrap_block()
-        };
-
-        match expr {
-            Expr { kind: ExprKind::MacCall(..), id, .. } => {
-                Some((PendingAnonConstInfo { block_was_stripped, ..pending_anon }, *id))
-            }
-            _ => None,
-        }
+        const_arg_sub_expr.optionally_braced_mac_call(pending_anon.block_was_stripped).map(
+            |(block_was_stripped, id)| {
+                (PendingAnonConstInfo { block_was_stripped, ..pending_anon }, id)
+            },
+        )
     }
 }
 
diff --git a/tests/crashes/131915.rs b/tests/crashes/131915.rs
deleted file mode 100644
index 58d45adcb3b..00000000000
--- a/tests/crashes/131915.rs
+++ /dev/null
@@ -1,13 +0,0 @@
-//@ known-bug: #131915
-
-macro_rules! y {
-    ( $($matcher:tt)*) => {
-        x
-    };
-}
-
-const _: A<
-    {
-        y! { test.tou8 }
-    },
->;
diff --git a/tests/ui/const-generics/early/const_arg_trivial_macro_expansion-2.rs b/tests/ui/const-generics/early/const_arg_trivial_macro_expansion-2.rs
new file mode 100644
index 00000000000..bce7ac5708a
--- /dev/null
+++ b/tests/ui/const-generics/early/const_arg_trivial_macro_expansion-2.rs
@@ -0,0 +1,20 @@
+// Regression test for #131915 where we did not handle macro calls as
+// statements correctly when determining if a const argument should
+// have a `DefId` created or not.
+
+macro_rules! y {
+    ( $($matcher:tt)*) => {
+        x
+        //~^ ERROR: cannot find value `x` in this scope
+    };
+}
+
+const _: A<
+    //~^ ERROR: free constant item without body
+    //~| ERROR: cannot find type `A` in this scope
+    {
+        y! { test.tou8 }
+    },
+>;
+
+fn main() {}
diff --git a/tests/ui/const-generics/early/const_arg_trivial_macro_expansion-2.stderr b/tests/ui/const-generics/early/const_arg_trivial_macro_expansion-2.stderr
new file mode 100644
index 00000000000..a3211b77623
--- /dev/null
+++ b/tests/ui/const-generics/early/const_arg_trivial_macro_expansion-2.stderr
@@ -0,0 +1,39 @@
+error: free constant item without body
+  --> $DIR/const_arg_trivial_macro_expansion-2.rs:12:1
+   |
+LL | / const _: A<
+LL | |
+LL | |
+LL | |     {
+LL | |         y! { test.tou8 }
+LL | |     },
+LL | | >;
+   | |  ^ help: provide a definition for the constant: `= <expr>;`
+   | |__|
+   |
+
+error[E0412]: cannot find type `A` in this scope
+  --> $DIR/const_arg_trivial_macro_expansion-2.rs:12:10
+   |
+LL | const _: A<
+   |          ^ not found in this scope
+
+error[E0425]: cannot find value `x` in this scope
+  --> $DIR/const_arg_trivial_macro_expansion-2.rs:7:9
+   |
+LL |         x
+   |         ^ not found in this scope
+...
+LL |         y! { test.tou8 }
+   |         ---------------- in this macro invocation
+   |
+   = note: this error originates in the macro `y` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: you might be missing a const parameter
+   |
+LL | const _<const x: /* Type */>: A<
+   |        +++++++++++++++++++++
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0412, E0425.
+For more information about an error, try `rustc --explain E0412`.
diff --git a/tests/ui/const-generics/early/const_arg_trivial_macro_expansion.rs b/tests/ui/const-generics/early/const_arg_trivial_macro_expansion.rs
new file mode 100644
index 00000000000..2fdd703ab6f
--- /dev/null
+++ b/tests/ui/const-generics/early/const_arg_trivial_macro_expansion.rs
@@ -0,0 +1,366 @@
+//@ known-bug: #132647
+//@ dont-check-compiler-stderr
+#![allow(unused_braces)]
+
+// FIXME(bootstrap): This isn't a known bug, we just don't want to write any error annotations.
+// this is hard because macro expansion errors have their span be inside the *definition* of the
+// macro rather than the line *invoking* it. This means we would wind up with hundreds of error
+// annotations on the macro definitions below rather than on any of the actual lines
+// that act as a "test".
+//
+// It's also made more complicated by the fact that compiletest generates "extra" expected
+// notes to give an assertable macro backtrace as otherwise there would *nothing* to annotate
+// on the actual test lines. All of these extra notes result in needing to write hundreds of
+// unnecessary notes on almost every line in this file.
+//
+// Even though this is marked `known-bug` it should still fail if this test starts ICEing which
+// is "enough" in this case.
+
+// Test that we correctly create definitions for anon consts even when
+// the trivial-ness of the expression is obscured by macro expansions.
+//
+// Acts as a regression test for: #131915 130321 128016
+
+// macros expanding to idents
+
+macro_rules! unbraced_ident {
+    () => {
+        ident
+    };
+}
+
+macro_rules! braced_ident {
+    () => {{ ident }};
+}
+
+macro_rules! unbraced_unbraced_ident {
+    () => {
+        unbraced_ident!()
+    };
+}
+
+macro_rules! braced_unbraced_ident {
+    () => {{ unbraced_ident!() }};
+}
+
+macro_rules! unbraced_braced_ident {
+    () => {
+        braced_ident!()
+    };
+}
+
+macro_rules! braced_braced_ident {
+    () => {{ braced_ident!() }};
+}
+
+// macros expanding to complex expr
+
+macro_rules! unbraced_expr {
+    () => {
+        ident.other
+    };
+}
+
+macro_rules! braced_expr {
+    () => {{ ident.otherent }};
+}
+
+macro_rules! unbraced_unbraced_expr {
+    () => {
+        unbraced_expr!()
+    };
+}
+
+macro_rules! braced_unbraced_expr {
+    () => {{ unbraced_expr!() }};
+}
+
+macro_rules! unbraced_braced_expr {
+    () => {
+        braced_expr!()
+    };
+}
+
+macro_rules! braced_braced_expr {
+    () => {{ braced_expr!() }};
+}
+
+#[rustfmt::skip]
+mod array_paren_call {
+    // Arrays where the expanded result is a `Res::Err`
+    fn array_0() -> [(); unbraced_unbraced_ident!()] { loop {} }
+    fn array_1() -> [(); braced_unbraced_ident!()] { loop {} }
+    fn array_2() -> [(); unbraced_braced_ident!()] { loop {} }
+    fn array_3() -> [(); braced_braced_ident!()] { loop {} }
+    fn array_4() -> [(); { unbraced_unbraced_ident!() }] { loop {} }
+    fn array_5() -> [(); { braced_unbraced_ident!() }] { loop {} }
+    fn array_6() -> [(); { unbraced_braced_ident!() }] { loop {} }
+    fn array_7() -> [(); { braced_braced_ident!() }] { loop {} }
+    fn array_8() -> [(); unbraced_ident!()] { loop {} }
+    fn array_9() -> [(); braced_ident!()] { loop {} }
+    fn array_10() -> [(); { unbraced_ident!() }] { loop {} }
+    fn array_11() -> [(); { braced_ident!() }] { loop {} }
+
+    // Arrays where the expanded result is a `Res::ConstParam`
+    fn array_12<const ident: usize>() -> [(); unbraced_unbraced_ident!()] { loop {} }
+    fn array_13<const ident: usize>() -> [(); braced_unbraced_ident!()] { loop {} }
+    fn array_14<const ident: usize>() -> [(); unbraced_braced_ident!()] { loop {} }
+    fn array_15<const ident: usize>() -> [(); braced_braced_ident!()] { loop {} }
+    fn array_16<const ident: usize>() -> [(); { unbraced_unbraced_ident!() }] { loop {} }
+    fn array_17<const ident: usize>() -> [(); { braced_unbraced_ident!() }] { loop {} }
+    fn array_18<const ident: usize>() -> [(); { unbraced_braced_ident!() }] { loop {} }
+    fn array_19<const ident: usize>() -> [(); { braced_braced_ident!() }] { loop {} }
+    fn array_20<const ident: usize>() -> [(); unbraced_ident!()] { loop {} }
+    fn array_21<const ident: usize>() -> [(); braced_ident!()] { loop {} }
+    fn array_22<const ident: usize>() -> [(); { unbraced_ident!() }] { loop {} }
+    fn array_23<const ident: usize>() -> [(); { braced_ident!() }] { loop {} }
+
+    // Arrays where the expanded result is a complex expr
+    fn array_24() -> [(); unbraced_unbraced_expr!()] { loop {} }
+    fn array_25() -> [(); braced_unbraced_expr!()] { loop {} }
+    fn array_26() -> [(); unbraced_braced_expr!()] { loop {} }
+    fn array_27() -> [(); braced_braced_expr!()] { loop {} }
+    fn array_28() -> [(); { unbraced_unbraced_expr!() }] { loop {} }
+    fn array_29() -> [(); { braced_unbraced_expr!() }] { loop {} }
+    fn array_30() -> [(); { unbraced_braced_expr!() }] { loop {} }
+    fn array_31() -> [(); { braced_braced_expr!() }] { loop {} }
+    fn array_32() -> [(); unbraced_expr!()] { loop {} }
+    fn array_33() -> [(); braced_expr!()] { loop {} }
+    fn array_34() -> [(); { unbraced_expr!() }] { loop {} }
+    fn array_35() -> [(); { braced_expr!() }] { loop {} }
+}
+
+#[rustfmt::skip]
+mod array_brace_call {
+    // Arrays where the expanded result is a `Res::Err`
+    fn array_0() -> [(); unbraced_unbraced_ident!{}] { loop {} }
+    fn array_1() -> [(); braced_unbraced_ident!{}] { loop {} }
+    fn array_2() -> [(); unbraced_braced_ident!{}] { loop {} }
+    fn array_3() -> [(); braced_braced_ident!{}] { loop {} }
+    fn array_4() -> [(); { unbraced_unbraced_ident!{} }] { loop {} }
+    fn array_5() -> [(); { braced_unbraced_ident!{} }] { loop {} }
+    fn array_6() -> [(); { unbraced_braced_ident!{} }] { loop {} }
+    fn array_7() -> [(); { braced_braced_ident!{} }] { loop {} }
+    fn array_8() -> [(); unbraced_ident!{}] { loop {} }
+    fn array_9() -> [(); braced_ident!{}] { loop {} }
+    fn array_10() -> [(); { unbraced_ident!{} }] { loop {} }
+    fn array_11() -> [(); { braced_ident!{} }] { loop {} }
+
+    // Arrays where the expanded result is a `Res::ConstParam`
+    fn array_12<const ident: usize>() -> [(); unbraced_unbraced_ident!{}] { loop {} }
+    fn array_13<const ident: usize>() -> [(); braced_unbraced_ident!{}] { loop {} }
+    fn array_14<const ident: usize>() -> [(); unbraced_braced_ident!{}] { loop {} }
+    fn array_15<const ident: usize>() -> [(); braced_braced_ident!{}] { loop {} }
+    fn array_16<const ident: usize>() -> [(); { unbraced_unbraced_ident!{} }] { loop {} }
+    fn array_17<const ident: usize>() -> [(); { braced_unbraced_ident!{} }] { loop {} }
+    fn array_18<const ident: usize>() -> [(); { unbraced_braced_ident!{} }] { loop {} }
+    fn array_19<const ident: usize>() -> [(); { braced_braced_ident!{} }] { loop {} }
+    fn array_20<const ident: usize>() -> [(); unbraced_ident!{}] { loop {} }
+    fn array_21<const ident: usize>() -> [(); braced_ident!{}] { loop {} }
+    fn array_22<const ident: usize>() -> [(); { unbraced_ident!{} }] { loop {} }
+    fn array_23<const ident: usize>() -> [(); { braced_ident!{} }] { loop {} }
+
+    // Arrays where the expanded result is a complex expr
+    fn array_24() -> [(); unbraced_unbraced_expr!{}] { loop {} }
+    fn array_25() -> [(); braced_unbraced_expr!{}] { loop {} }
+    fn array_26() -> [(); unbraced_braced_expr!{}] { loop {} }
+    fn array_27() -> [(); braced_braced_expr!{}] { loop {} }
+    fn array_28() -> [(); { unbraced_unbraced_expr!{} }] { loop {} }
+    fn array_29() -> [(); { braced_unbraced_expr!{} }] { loop {} }
+    fn array_30() -> [(); { unbraced_braced_expr!{} }] { loop {} }
+    fn array_31() -> [(); { braced_braced_expr!{} }] { loop {} }
+    fn array_32() -> [(); unbraced_expr!{}] { loop {} }
+    fn array_33() -> [(); braced_expr!{}] { loop {} }
+    fn array_34() -> [(); { unbraced_expr!{} }] { loop {} }
+    fn array_35() -> [(); { braced_expr!{} }] { loop {} }
+}
+
+#[rustfmt::skip]
+mod array_square_call {
+    // Arrays where the expanded result is a `Res::Err`
+    fn array_0() -> [(); unbraced_unbraced_ident![]] { loop {} }
+    fn array_1() -> [(); braced_unbraced_ident![]] { loop {} }
+    fn array_2() -> [(); unbraced_braced_ident![]] { loop {} }
+    fn array_3() -> [(); braced_braced_ident![]] { loop {} }
+    fn array_4() -> [(); { unbraced_unbraced_ident![] }] { loop {} }
+    fn array_5() -> [(); { braced_unbraced_ident![] }] { loop {} }
+    fn array_6() -> [(); { unbraced_braced_ident![] }] { loop {} }
+    fn array_7() -> [(); { braced_braced_ident![] }] { loop {} }
+    fn array_8() -> [(); unbraced_ident![]] { loop {} }
+    fn array_9() -> [(); braced_ident![]] { loop {} }
+    fn array_10() -> [(); { unbraced_ident![] }] { loop {} }
+    fn array_11() -> [(); { braced_ident![] }] { loop {} }
+
+    // Arrays where the expanded result is a `Res::ConstParam`
+    fn array_12<const ident: usize>() -> [(); unbraced_unbraced_ident![]] { loop {} }
+    fn array_13<const ident: usize>() -> [(); braced_unbraced_ident![]] { loop {} }
+    fn array_14<const ident: usize>() -> [(); unbraced_braced_ident![]] { loop {} }
+    fn array_15<const ident: usize>() -> [(); braced_braced_ident![]] { loop {} }
+    fn array_16<const ident: usize>() -> [(); { unbraced_unbraced_ident![] }] { loop {} }
+    fn array_17<const ident: usize>() -> [(); { braced_unbraced_ident![] }] { loop {} }
+    fn array_18<const ident: usize>() -> [(); { unbraced_braced_ident![] }] { loop {} }
+    fn array_19<const ident: usize>() -> [(); { braced_braced_ident![] }] { loop {} }
+    fn array_20<const ident: usize>() -> [(); unbraced_ident![]] { loop {} }
+    fn array_21<const ident: usize>() -> [(); braced_ident![]] { loop {} }
+    fn array_22<const ident: usize>() -> [(); { unbraced_ident![] }] { loop {} }
+    fn array_23<const ident: usize>() -> [(); { braced_ident![] }] { loop {} }
+
+    // Arrays where the expanded result is a complex expr
+    fn array_24() -> [(); unbraced_unbraced_expr![]] { loop {} }
+    fn array_25() -> [(); braced_unbraced_expr![]] { loop {} }
+    fn array_26() -> [(); unbraced_braced_expr![]] { loop {} }
+    fn array_27() -> [(); braced_braced_expr![]] { loop {} }
+    fn array_28() -> [(); { unbraced_unbraced_expr![] }] { loop {} }
+    fn array_29() -> [(); { braced_unbraced_expr![] }] { loop {} }
+    fn array_30() -> [(); { unbraced_braced_expr![] }] { loop {} }
+    fn array_31() -> [(); { braced_braced_expr![] }] { loop {} }
+    fn array_32() -> [(); unbraced_expr![]] { loop {} }
+    fn array_33() -> [(); braced_expr![]] { loop {} }
+    fn array_34() -> [(); { unbraced_expr![] }] { loop {} }
+    fn array_35() -> [(); { braced_expr![] }] { loop {} }
+}
+
+struct Foo<const N: usize>;
+
+#[rustfmt::skip]
+mod adt_paren_call {
+    use super::Foo;
+
+    // An ADT where the expanded result is a `Res::Err`
+    fn adt_0() -> Foo<unbraced_unbraced_ident!()> { loop {} }
+    fn adt_1() -> Foo<braced_unbraced_ident!()> { loop {} }
+    fn adt_2() -> Foo<unbraced_braced_ident!()> { loop {} }
+    fn adt_3() -> Foo<braced_braced_ident!()> { loop {} }
+    fn adt_4() -> Foo<{ unbraced_unbraced_ident!() }> { loop {} }
+    fn adt_5() -> Foo<{ braced_unbraced_ident!() }> { loop {} }
+    fn adt_6() -> Foo<{ unbraced_braced_ident!() }> { loop {} }
+    fn adt_7() -> Foo<{ braced_braced_ident!() }> { loop {} }
+    fn adt_8() -> Foo<unbraced_ident!()> { loop {} }
+    fn adt_9() -> Foo<braced_ident!()> { loop {} }
+    fn adt_10() -> Foo<{ unbraced_ident!() }> { loop {} }
+    fn adt_11() -> Foo<{ braced_ident!() }> { loop {} }
+
+    // An ADT where the expanded result is a `Res::ConstParam`
+    fn adt_12<const ident: usize>() -> Foo<unbraced_unbraced_ident!()> { loop {} }
+    fn adt_13<const ident: usize>() -> Foo<braced_unbraced_ident!()> { loop {} }
+    fn adt_14<const ident: usize>() -> Foo<unbraced_braced_ident!()> { loop {} }
+    fn adt_15<const ident: usize>() -> Foo<braced_braced_ident!()> { loop {} }
+    fn adt_16<const ident: usize>() -> Foo<{ unbraced_unbraced_ident!() }> { loop {} }
+    fn adt_17<const ident: usize>() -> Foo<{ braced_unbraced_ident!() }> { loop {} }
+    fn adt_18<const ident: usize>() -> Foo<{ unbraced_braced_ident!() }> { loop {} }
+    fn adt_19<const ident: usize>() -> Foo<{ braced_braced_ident!() }> { loop {} }
+    fn adt_20<const ident: usize>() -> Foo<unbraced_ident!()> { loop {} }
+    fn adt_21<const ident: usize>() -> Foo<braced_ident!()> { loop {} }
+    fn adt_22<const ident: usize>() -> Foo<{ unbraced_ident!() }> { loop {} }
+    fn adt_23<const ident: usize>() -> Foo<{ braced_ident!() }> { loop {} }
+
+    // An ADT where the expanded result is a complex expr
+    fn array_24() -> Foo<unbraced_unbraced_expr!()> { loop {} }
+    fn array_25() -> Foo<braced_unbraced_expr!()> { loop {} }
+    fn array_26() -> Foo<unbraced_braced_expr!()> { loop {} }
+    fn array_27() -> Foo<braced_braced_expr!()> { loop {} }
+    fn array_28() -> Foo<{ unbraced_unbraced_expr!() }> { loop {} }
+    fn array_29() -> Foo<{ braced_unbraced_expr!() }> { loop {} }
+    fn array_30() -> Foo<{ unbraced_braced_expr!() }> { loop {} }
+    fn array_31() -> Foo<{ braced_braced_expr!() }> { loop {} }
+    fn array_32() -> Foo<unbraced_expr!()> { loop {} }
+    fn array_33() -> Foo<braced_expr!()> { loop {} }
+    fn array_34() -> Foo<{ unbraced_expr!() }> { loop {} }
+    fn array_35() -> Foo<{ braced_expr!() }> { loop {} }
+}
+
+#[rustfmt::skip]
+mod adt_brace_call {
+    use super::Foo;
+
+    // An ADT where the expanded result is a `Res::Err`
+    fn adt_0() -> Foo<unbraced_unbraced_ident!{}> { loop {} }
+    fn adt_1() -> Foo<braced_unbraced_ident!{}> { loop {} }
+    fn adt_2() -> Foo<unbraced_braced_ident!{}> { loop {} }
+    fn adt_3() -> Foo<braced_braced_ident!{}> { loop {} }
+    fn adt_4() -> Foo<{ unbraced_unbraced_ident!{} }> { loop {} }
+    fn adt_5() -> Foo<{ braced_unbraced_ident!{} }> { loop {} }
+    fn adt_6() -> Foo<{ unbraced_braced_ident!{} }> { loop {} }
+    fn adt_7() -> Foo<{ braced_braced_ident!{} }> { loop {} }
+    fn adt_8() -> Foo<unbraced_ident!{}> { loop {} }
+    fn adt_9() -> Foo<braced_ident!{}> { loop {} }
+    fn adt_10() -> Foo<{ unbraced_ident!{} }> { loop {} }
+    fn adt_11() -> Foo<{ braced_ident!{} }> { loop {} }
+
+    // An ADT where the expanded result is a `Res::ConstParam`
+    fn adt_12<const ident: usize>() -> Foo<unbraced_unbraced_ident!{}> { loop {} }
+    fn adt_13<const ident: usize>() -> Foo<braced_unbraced_ident!{}> { loop {} }
+    fn adt_14<const ident: usize>() -> Foo<unbraced_braced_ident!{}> { loop {} }
+    fn adt_15<const ident: usize>() -> Foo<braced_braced_ident!{}> { loop {} }
+    fn adt_16<const ident: usize>() -> Foo<{ unbraced_unbraced_ident!{} }> { loop {} }
+    fn adt_17<const ident: usize>() -> Foo<{ braced_unbraced_ident!{} }> { loop {} }
+    fn adt_18<const ident: usize>() -> Foo<{ unbraced_braced_ident!{} }> { loop {} }
+    fn adt_19<const ident: usize>() -> Foo<{ braced_braced_ident!{} }> { loop {} }
+    fn adt_20<const ident: usize>() -> Foo<unbraced_ident!{}> { loop {} }
+    fn adt_21<const ident: usize>() -> Foo<braced_ident!{}> { loop {} }
+    fn adt_22<const ident: usize>() -> Foo<{ unbraced_ident!{} }> { loop {} }
+    fn adt_23<const ident: usize>() -> Foo<{ braced_ident!{} }> { loop {} }
+
+    // An ADT where the expanded result is a complex expr
+    fn array_24() -> Foo<unbraced_unbraced_expr!{}> { loop {} }
+    fn array_25() -> Foo<braced_unbraced_expr!{}> { loop {} }
+    fn array_26() -> Foo<unbraced_braced_expr!{}> { loop {} }
+    fn array_27() -> Foo<braced_braced_expr!{}> { loop {} }
+    fn array_28() -> Foo<{ unbraced_unbraced_expr!{} }> { loop {} }
+    fn array_29() -> Foo<{ braced_unbraced_expr!{} }> { loop {} }
+    fn array_30() -> Foo<{ unbraced_braced_expr!{} }> { loop {} }
+    fn array_31() -> Foo<{ braced_braced_expr!{} }> { loop {} }
+    fn array_32() -> Foo<unbraced_expr!{}> { loop {} }
+    fn array_33() -> Foo<braced_expr!{}> { loop {} }
+    fn array_34() -> Foo<{ unbraced_expr!{} }> { loop {} }
+    fn array_35() -> Foo<{ braced_expr!{} }> { loop {} }
+}
+
+#[rustfmt::skip]
+mod adt_square_call {
+    use super::Foo;
+
+    // An ADT where the expanded result is a `Res::Err`
+    fn adt_0() -> Foo<unbraced_unbraced_ident![]> { loop {} }
+    fn adt_1() -> Foo<braced_unbraced_ident![]> { loop {} }
+    fn adt_2() -> Foo<unbraced_braced_ident![]> { loop {} }
+    fn adt_3() -> Foo<braced_braced_ident![]> { loop {} }
+    fn adt_4() -> Foo<{ unbraced_unbraced_ident![] }> { loop {} }
+    fn adt_5() -> Foo<{ braced_unbraced_ident![] }> { loop {} }
+    fn adt_6() -> Foo<{ unbraced_braced_ident![] }> { loop {} }
+    fn adt_7() -> Foo<{ braced_braced_ident![] }> { loop {} }
+    fn adt_8() -> Foo<unbraced_ident![]> { loop {} }
+    fn adt_9() -> Foo<braced_ident![]> { loop {} }
+    fn adt_10() -> Foo<{ unbraced_ident![] }> { loop {} }
+    fn adt_11() -> Foo<{ braced_ident![] }> { loop {} }
+
+    // An ADT where the expanded result is a `Res::ConstParam`
+    fn adt_12<const ident: usize>() -> Foo<unbraced_unbraced_ident![]> { loop {} }
+    fn adt_13<const ident: usize>() -> Foo<braced_unbraced_ident![]> { loop {} }
+    fn adt_14<const ident: usize>() -> Foo<unbraced_braced_ident![]> { loop {} }
+    fn adt_15<const ident: usize>() -> Foo<braced_braced_ident![]> { loop {} }
+    fn adt_16<const ident: usize>() -> Foo<{ unbraced_unbraced_ident![] }> { loop {} }
+    fn adt_17<const ident: usize>() -> Foo<{ braced_unbraced_ident![] }> { loop {} }
+    fn adt_18<const ident: usize>() -> Foo<{ unbraced_braced_ident![] }> { loop {} }
+    fn adt_19<const ident: usize>() -> Foo<{ braced_braced_ident![] }> { loop {} }
+    fn adt_20<const ident: usize>() -> Foo<unbraced_ident![]> { loop {} }
+    fn adt_21<const ident: usize>() -> Foo<braced_ident![]> { loop {} }
+    fn adt_22<const ident: usize>() -> Foo<{ unbraced_ident![] }> { loop {} }
+    fn adt_23<const ident: usize>() -> Foo<{ braced_ident![] }> { loop {} }
+
+    // An ADT where the expanded result is a complex expr
+    fn array_24() -> Foo<unbraced_unbraced_expr![]> { loop {} }
+    fn array_25() -> Foo<braced_unbraced_expr![]> { loop {} }
+    fn array_26() -> Foo<unbraced_braced_expr![]> { loop {} }
+    fn array_27() -> Foo<braced_braced_expr![]> { loop {} }
+    fn array_28() -> Foo<{ unbraced_unbraced_expr![] }> { loop {} }
+    fn array_29() -> Foo<{ braced_unbraced_expr![] }> { loop {} }
+    fn array_30() -> Foo<{ unbraced_braced_expr![] }> { loop {} }
+    fn array_31() -> Foo<{ braced_braced_expr![] }> { loop {} }
+    fn array_32() -> Foo<unbraced_expr![]> { loop {} }
+    fn array_33() -> Foo<braced_expr![]> { loop {} }
+    fn array_34() -> Foo<{ unbraced_expr![] }> { loop {} }
+    fn array_35() -> Foo<{ braced_expr![] }> { loop {} }
+}
+
+fn main() {}