From 429143af4299327a816b9d50e13a4cfc3ba247a7 Mon Sep 17 00:00:00 2001
From: Ed Page <eopage@gmail.com>
Date: Tue, 16 Aug 2022 15:03:35 -0500
Subject: [PATCH] fix: Remove once_cell dependency from derive

With being able to accept owned types now, `clap_derive` no longer needs
`once_cell` to make dynamic data static.

This helps towards #1365, #2037
---
 Cargo.toml               |  2 +-
 clap_derive/src/attrs.rs | 38 ++++++++------------------------------
 src/lib.rs               |  2 +-
 3 files changed, 10 insertions(+), 32 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 214c230eec6..eed7a7d9b76 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -69,7 +69,7 @@ suggestions = ["dep:strsim"]
 
 # Optional
 deprecated = ["clap_derive?/deprecated"] # Guided experience to prepare for next breaking release (at different stages of development, this may become default)
-derive = ["clap_derive", "dep:once_cell"]
+derive = ["clap_derive"]
 cargo = ["dep:once_cell"] # Disable if you're not using Cargo, enables Cargo-env-var-dependent macros
 wrap_help = ["dep:terminal_size", "textwrap/terminal_size"]
 env = [] # Use environment variables during arg parsing
diff --git a/clap_derive/src/attrs.rs b/clap_derive/src/attrs.rs
index 52ce9b46005..79c109d3a2c 100644
--- a/clap_derive/src/attrs.rs
+++ b/clap_derive/src/attrs.rs
@@ -504,11 +504,10 @@ impl Attrs {
                         })
                     } else {
                         quote_spanned!(ident.span()=> {
-                            static DEFAULT_VALUE: clap::__macro_refs::once_cell::sync::Lazy<String> = clap::__macro_refs::once_cell::sync::Lazy::new(|| {
+                            {
                                 let val: #ty = #val;
                                 ::std::string::ToString::to_string(&val)
-                            });
-                            &*DEFAULT_VALUE
+                            }
                         })
                     };
 
@@ -558,10 +557,7 @@ impl Attrs {
 
                                 }
 
-                                static DEFAULT_VALUES: clap::__macro_refs::once_cell::sync::Lazy<Vec<&str>> = clap::__macro_refs::once_cell::sync::Lazy::new(|| {
-                                    iter_to_vals(#expr)
-                                });
-                                DEFAULT_VALUES.iter().copied()
+                                iter_to_vals(#expr)
                             }
                         })
                     } else {
@@ -575,14 +571,7 @@ impl Attrs {
 
                                 }
 
-                                static DEFAULT_STRINGS: clap::__macro_refs::once_cell::sync::Lazy<Vec<::std::string::String>> = clap::__macro_refs::once_cell::sync::Lazy::new(|| {
-                                    iter_to_vals(#expr)
-                                });
-
-                                static DEFAULT_VALUES: clap::__macro_refs::once_cell::sync::Lazy<Vec<&str>> = clap::__macro_refs::once_cell::sync::Lazy::new(|| {
-                                    DEFAULT_STRINGS.iter().map(::std::string::String::as_str).collect()
-                                });
-                                DEFAULT_VALUES.iter().copied()
+                                iter_to_vals(#expr)
                             }
                         })
                     };
@@ -619,11 +608,10 @@ impl Attrs {
                         })
                     } else {
                         quote_spanned!(ident.span()=> {
-                            static DEFAULT_VALUE: clap::__macro_refs::once_cell::sync::Lazy<::std::ffi::OsString> = clap::__macro_refs::once_cell::sync::Lazy::new(|| {
+                            {
                                 let val: #ty = #val;
                                 ::std::ffi::OsString::from(val)
-                            });
-                            &*DEFAULT_VALUE
+                            }
                         })
                     };
 
@@ -674,10 +662,7 @@ impl Attrs {
 
                                 }
 
-                                static DEFAULT_VALUES: clap::__macro_refs::once_cell::sync::Lazy<Vec<&::std::ffi::OsStr>> = clap::__macro_refs::once_cell::sync::Lazy::new(|| {
-                                    iter_to_vals(#expr)
-                                });
-                                DEFAULT_VALUES.iter().copied()
+                                iter_to_vals(#expr)
                             }
                         })
                     } else {
@@ -691,14 +676,7 @@ impl Attrs {
 
                                 }
 
-                                static DEFAULT_OS_STRINGS: clap::__macro_refs::once_cell::sync::Lazy<Vec<::std::ffi::OsString>> = clap::__macro_refs::once_cell::sync::Lazy::new(|| {
-                                    iter_to_vals(#expr)
-                                });
-
-                                static DEFAULT_VALUES: clap::__macro_refs::once_cell::sync::Lazy<Vec<&::std::ffi::OsStr>> = clap::__macro_refs::once_cell::sync::Lazy::new(|| {
-                                    DEFAULT_OS_STRINGS.iter().map(::std::ffi::OsString::as_os_str).collect()
-                                });
-                                DEFAULT_VALUES.iter().copied()
+                                iter_to_vals(#expr)
                             }
                         })
                     };
diff --git a/src/lib.rs b/src/lib.rs
index d15b969814d..37aa246f0ba 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -131,7 +131,7 @@ pub mod _tutorial;
 
 #[doc(hidden)]
 pub mod __macro_refs {
-    #[cfg(any(feature = "derive", feature = "cargo"))]
+    #[cfg(feature = "cargo")]
     #[doc(hidden)]
     pub use once_cell;
 }