From c8fb28683b4602686ed35f6f57b8e8714e8dab0a Mon Sep 17 00:00:00 2001
From: Jules Bertholet <julesbertholet@quoi.xyz>
Date: Sun, 21 Sep 2025 10:25:58 -0400
Subject: [PATCH 1/3] Support `cfg(true)` and `cfg(false)`

---
 src/lib.rs | 31 +++++++++++++++++++++----------
 1 file changed, 21 insertions(+), 10 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 8c26b6f..952c9a2 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -33,9 +33,9 @@
 #[macro_export]
 macro_rules! cfg_if {
     (
-        if #[cfg( $i_meta:meta )] { $( $i_tokens:tt )* }
+        if #[cfg( $($i_meta:tt)+ )] { $( $i_tokens:tt )* }
         $(
-            else if #[cfg( $ei_meta:meta )] { $( $ei_tokens:tt )* }
+            else if #[cfg( $($ei_meta:tt)+ )] { $( $ei_tokens:tt )* }
         )*
         $(
             else { $( $e_tokens:tt )* }
@@ -43,9 +43,9 @@ macro_rules! cfg_if {
     ) => {
         $crate::cfg_if! {
             @__items () ;
-            (( $i_meta ) ( $( $i_tokens )* )),
+            (( $($i_meta)+ ) ( $( $i_tokens )* )),
             $(
-                (( $ei_meta ) ( $( $ei_tokens )* )),
+                (( $($ei_meta)+ ) ( $( $ei_tokens )* )),
             )*
             $(
                 (() ( $( $e_tokens )* )),
@@ -57,18 +57,18 @@ macro_rules! cfg_if {
     //
     // Collects all the previous cfgs in a list at the beginning, so they can be
     // negated. After the semicolon are all the remaining items.
-    (@__items ( $( $_:meta , )* ) ; ) => {};
+    (@__items ( $( ($($_:tt)*) , )* ) ; ) => {};
     (
-        @__items ( $( $no:meta , )* ) ;
-        (( $( $yes:meta )? ) ( $( $tokens:tt )* )),
+        @__items ( $( ($($no:tt)+) , )* ) ;
+        (( $( $($yes:tt)+ )? ) ( $( $tokens:tt )* )),
         $( $rest:tt , )*
     ) => {
         // Emit all items within one block, applying an appropriate #[cfg]. The
         // #[cfg] will require all `$yes` matchers specified and must also negate
         // all previous matchers.
         #[cfg(all(
-            $( $yes , )?
-            not(any( $( $no ),* ))
+            $( $($yes)+ , )?
+            not(any( $( $($no)+ ),* ))
         ))]
         // Subtle: You might think we could put `$( $tokens )*` here. But if
         // that contains multiple items then the `#[cfg(all(..))]` above would
@@ -84,7 +84,7 @@ macro_rules! cfg_if {
         // our `$yes` matchers to the list of `$no` matchers as future emissions
         // will have to negate everything we just matched as well.
         $crate::cfg_if! {
-            @__items ( $( $no , )* $( $yes , )? ) ;
+            @__items ( $( ($($no)+) , )* $( ($($yes)+) , )? ) ;
             $( $rest , )*
         }
     };
@@ -196,4 +196,15 @@ mod tests {
             }
         }
     }
+
+    cfg_if! {
+        if #[cfg(false)] {
+            fn works6() -> bool { false }
+        } else if #[cfg(true)] {
+            #[allow(dead_code)]
+            fn works6() -> bool { true }
+        } else if #[cfg(false)] {
+            fn works6() -> bool { true }
+        }
+    }
 }

From 999dfcc8e446eadbb4106a84afaf322f9d4dc9f7 Mon Sep 17 00:00:00 2001
From: Jules Bertholet <julesbertholet@quoi.xyz>
Date: Sun, 21 Sep 2025 10:34:09 -0400
Subject: [PATCH 2/3] Don't test `cfg(true)`/`cfg(false)` on MSRV
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

These aren’t supported yet there.
---
 .github/workflows/main.yaml | 2 +-
 src/lib.rs                  | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/main.yaml b/.github/workflows/main.yaml
index 644e3fc..b037e95 100644
--- a/.github/workflows/main.yaml
+++ b/.github/workflows/main.yaml
@@ -31,7 +31,7 @@ jobs:
         run: |
           set -eux
           # Remove `-Dwarnings` at the MSRV since lints may be different
-          [ "${{ matrix.rust }}" = "1.32" ] && export RUSTFLAGS=""
+          [ "${{ matrix.rust }}" = "1.32" ] && export RUSTFLAGS="--cfg MSRV_TEST"
           cargo test
 
   rustfmt:
diff --git a/src/lib.rs b/src/lib.rs
index 952c9a2..9b64530 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -197,6 +197,7 @@ mod tests {
         }
     }
 
+    #[cfg(not(MSRV_TEST))]
     cfg_if! {
         if #[cfg(false)] {
             fn works6() -> bool { false }

From 5387b4ceed20688cadfb3324c135f467814bbcf7 Mon Sep 17 00:00:00 2001
From: Jules Bertholet <julesbertholet@quoi.xyz>
Date: Sun, 21 Sep 2025 21:09:09 -0400
Subject: [PATCH 3/3] Address review comments

---
 .github/workflows/main.yaml |  2 +-
 src/lib.rs                  | 25 +++++++++++++------------
 2 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/.github/workflows/main.yaml b/.github/workflows/main.yaml
index b037e95..7288a62 100644
--- a/.github/workflows/main.yaml
+++ b/.github/workflows/main.yaml
@@ -31,7 +31,7 @@ jobs:
         run: |
           set -eux
           # Remove `-Dwarnings` at the MSRV since lints may be different
-          [ "${{ matrix.rust }}" = "1.32" ] && export RUSTFLAGS="--cfg MSRV_TEST"
+          [ "${{ matrix.rust }}" = "1.32" ] && export RUSTFLAGS="--cfg msrv_test"
           cargo test
 
   rustfmt:
diff --git a/src/lib.rs b/src/lib.rs
index 9b64530..2c7414e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -154,6 +154,17 @@ mod tests {
         }
     );
 
+    #[cfg(not(msrv_test))]
+    cfg_if! {
+        if #[cfg(false)] {
+            fn works6() -> bool { false }
+        } else if #[cfg(true)] {
+            fn works6() -> bool { true }
+        } else if #[cfg(false)] {
+            fn works6() -> bool { false }
+        }
+    }
+
     #[test]
     fn it_works() {
         assert!(works1().is_some());
@@ -161,6 +172,8 @@ mod tests {
         assert!(works3());
         assert!(works4().is_some());
         assert!(works5());
+        #[cfg(not(msrv_test))]
+        assert!(works6());
     }
 
     #[test]
@@ -196,16 +209,4 @@ mod tests {
             }
         }
     }
-
-    #[cfg(not(MSRV_TEST))]
-    cfg_if! {
-        if #[cfg(false)] {
-            fn works6() -> bool { false }
-        } else if #[cfg(true)] {
-            #[allow(dead_code)]
-            fn works6() -> bool { true }
-        } else if #[cfg(false)] {
-            fn works6() -> bool { true }
-        }
-    }
 }