glib-macros: make proc-macro-crate optional

The "proc-macro-crate" brings many dependencies (toml_edit, indexmap,
hashbrow, winnow...) and is often needless.

This helps bring glib-rs to projects like QEMU that try to use a minimal
set of dependencies, and package dependencies manually with meson wraps.

Signed-off-by: Marc-André Lureau <[email protected]>

Author: elmarco

Cargo.toml

@@ -48,6 +48,6 @@ pango = { path = "pango", version = "0.22" }
 pangocairo-sys = { path = "pangocairo/sys", version = "0.22" }
 cairo-sys-rs = { path = "cairo/sys", version = "0.22" }
 cairo-rs = { path = "cairo", version = "0.22" }
-glib-macros = { path = "glib-macros", version = "0.22" }
+glib-macros = { path = "glib-macros", version = "0.22", default-features = false }
 gdk-pixbuf-sys = { path = "gdk-pixbuf/sys", version = "0.22" }
 graphene-sys = { path = "graphene/sys", version = "0.22" }

glib-macros/Cargo.toml

@@ -12,12 +12,16 @@ repository.workspace = true
 rust-version.workspace = true
 version.workspace = true
 
+[features]
+default = ["proc_macro_crate"]
+proc_macro_crate = ["proc-macro-crate"]
+
 [dependencies]
 heck = "0.5"
 proc-macro2 = "1.0"
 quote = "1.0"
 syn = { version = "2.0.106", features = ["full"] }
-proc-macro-crate = "3.3"
+proc-macro-crate = { version = "3.3", optional = true }
 
 [lib]
 proc-macro = true

glib-macros/src/utils.rs

@@ -1,7 +1,6 @@
 // Take a look at the license at the top of the repository in the LICENSE file.
 
 use proc_macro2::{Ident, Span, TokenStream};
-use proc_macro_crate::crate_name;
 use quote::{quote, quote_spanned, ToTokens};
 use syn::{
     meta::ParseNestedMeta, parse::Parse, punctuated::Punctuated, spanned::Spanned, token::Comma,
@@ -185,8 +184,9 @@ pub fn parse_optional_nested_meta_items<'a>(
     }
 }
 
+#[cfg(feature = "proc_macro_crate")]
 pub fn crate_ident_new() -> TokenStream {
-    use proc_macro_crate::FoundCrate;
+    use proc_macro_crate::{crate_name, FoundCrate};
 
     match crate_name("glib") {
         Ok(FoundCrate::Name(name)) => Some(name),
@@ -214,6 +214,12 @@ pub fn crate_ident_new() -> TokenStream {
     })
 }
 
+#[cfg(not(feature = "proc_macro_crate"))]
+pub fn crate_ident_new() -> TokenStream {
+    let glib = Ident::new("glib", Span::call_site());
+    quote!(#glib)
+}
+
 // Generate i32 to enum mapping, used to implement
 // glib::translate::TryFromGlib<i32>, such as:
 //

glib/Cargo.toml

@@ -26,7 +26,7 @@ futures-channel = "0.3"
 futures-util = "0.3"
 glib-sys.workspace = true
 gobject-sys.workspace = true
-glib-macros.workspace = true
+glib-macros = { workspace = true, default-features = false }
 rs-log = { package = "log", version = "0.4", optional = true }
 smallvec = { version = "1.15", features = ["union", "const_generics", "const_new"] }
 gio-sys = { workspace = true, optional = true }

glib/src/lib.rs

@@ -26,6 +26,9 @@
 //! [`translate`]: mod@translate
 #![doc = include_str!("../README.md")]
 
+// for macros
+extern crate self as glib;
+
 pub use bitflags;
 #[doc(hidden)]
 pub use glib_macros::cstr_bytes;