Is it possible to support no_std for this project?

[YdrMaster]

Support no_std will be useful.

[baoyachi]

Recently，not yet. I'm not clear about rust 'no_std' develop

[baoyachi]

For long time, It's should be support.

[YdrMaster]

thx.

[mchodzikiewicz]

Hi,

I am missing this crate so badly in my no_std projects 🙁

Having a quick look it should be fairly simple introducing a split between generation part in build.rs and usage part in final binary. If I see correctly, most of what's available in the later is const &str which is 100% no_std and no-alloc compliant

This way you could add something like shadow-rs-gen to [build-dependencies] and shadow-rs-consts to [dependencies]

[mchodzikiewicz]

Oh! I just made it work in 5mins (in a messy way)

I am planning to prepare a cleaner PR soon with additional crate in a workspace and feature gates, but for now if anybody is interested in hacking it up, you need to:

• Disable generation of print_build_in() because it uses println!() inside
• Substitute shadow::formatcp with const_format::formatcp
• Add shadow-rs you modified this way to your [build-dependencies] instead of [dependencies]
• Add const_format crate to your project
• Copy shadow macro to your project:

#[macro_export]
macro_rules! shadow {
    ($build_mod:ident) => {
        #[doc = r#"shadow-rs mod"#]
        pub mod $build_mod {
            include!(concat!(env!("OUT_DIR"), "/shadow.rs"));
        }
    };
}

First two points as diff of shadow-rs:

diff --git a/src/gen_const.rs b/src/gen_const.rs
index d433da4..5548b2e 100644
--- a/src/gen_const.rs
+++ b/src/gen_const.rs
@@ -19,7 +19,7 @@ const VERSION_BRANCH_CONST: (&str, &str) = (
     r#"/// A long version string describing the project.
 /// The version string contains the package version, branch, commit hash, build time, and build environment on separate lines.
 /// This constant is suitable for printing to the user."#,
-    r##"pub const VERSION:&str = shadow_rs::formatcp!(r#"
+    r##"pub const VERSION:&str = const_format::formatcp!(r#"
 pkg_version:{}
 branch:{}
 commit_hash:{}
@@ -32,7 +32,7 @@ const VERSION_TAG_CONST: (&str, &str) = (
     r#"/// A long version string describing the project.
 /// The version string contains the package version, current Git tag, commit hash, build time, and build environment on separate lines.
 /// This constant is suitable for printing to the user."#,
-    r##"pub const VERSION:&str = shadow_rs::formatcp!(r#"
+    r##"pub const VERSION:&str = const_format::formatcp!(r#"
 pkg_version:{}
 tag:{}
 commit_hash:{}
@@ -43,7 +43,7 @@ build_env:{},{}"#,PKG_VERSION, TAG, SHORT_COMMIT, BUILD_TIME, RUST_VERSION, RUST
 
 const CLAP_VERSION_BRANCH_CONST: (&str, &str) = (
     r#"#[deprecated = "Replaced with `CLAP_LONG_VERSION`"]"#,
-    r##"pub const CLAP_VERSION:&str = shadow_rs::formatcp!(r#"{}
+    r##"pub const CLAP_VERSION:&str = const_format::formatcp!(r#"{}
 branch:{}
 commit_hash:{}
 build_time:{}
@@ -53,7 +53,7 @@ build_env:{},{}"#,PKG_VERSION, BRANCH, SHORT_COMMIT, BUILD_TIME, RUST_VERSION, R
 
 const CLAP_VERSION_TAG_CONST: (&str, &str) = (
     r#"#[deprecated = "Replaced with `CLAP_LONG_VERSION`"]"#,
-    r##"pub const CLAP_VERSION:&str = shadow_rs::formatcp!(r#"{}
+    r##"pub const CLAP_VERSION:&str = const_format::formatcp!(r#"{}
 tag:{}
 commit_hash:{}
 build_time:{}
@@ -65,7 +65,7 @@ const CLAP_LONG_VERSION_BRANCH_CONST: (&str, &str) = (
     r#"/// A long version string describing the project.
 /// The version string contains the package version, branch, commit hash, build time, and build environment on separate lines.
 /// This constant is intended to be used by clap or other CLI tools as a long version string."#,
-    r##"pub const CLAP_LONG_VERSION:&str = shadow_rs::formatcp!(r#"{}
+    r##"pub const CLAP_LONG_VERSION:&str = const_format::formatcp!(r#"{}
 branch:{}
 commit_hash:{}
 build_time:{}
@@ -77,7 +77,7 @@ const CLAP_LONG_VERSION_TAG_CONST: (&str, &str) = (
     r#"/// A long version string describing the project.
 /// The version string contains the package version, current Git tag, commit hash, build time, and build environment on separate lines.
 /// This constant is intended to be used by clap or other CLI tools as a long version string."#,
-    r##"pub const CLAP_LONG_VERSION:&str = shadow_rs::formatcp!(r#"{}
+    r##"pub const CLAP_LONG_VERSION:&str = const_format::formatcp!(r#"{}
 tag:{}
 commit_hash:{}
 build_time:{}
diff --git a/src/lib.rs b/src/lib.rs
index f0f0c1c..745ad99 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -663,15 +663,15 @@ impl Shadow {
             print_val.push_str(tmp.as_str());
         }
 
-        let everything_define = format!(
-            "/// Prints all built-in `shadow-rs` build constants to standard output.\n\
-            #[allow(dead_code)]\n\
-            {CARGO_CLIPPY_ALLOW_ALL}\n\
-            pub fn print_build_in() {\
-            {{print_val}}\
-            }\n",
-        );
-        writeln!(&self.f, "{everything_define}")?;
+        // let everything_define = format!(
+        //     "/// Prints all built-in `shadow-rs` build constants to standard output.\n\
+        //     #[allow(dead_code)]\n\
+        //     {CARGO_CLIPPY_ALLOW_ALL}\n\
+        //     pub fn print_build_in() {\
+        //     {{print_val}}\
+        //     }\n",
+        // );
+        // writeln!(&self.f, "{everything_define}")?;
 
         writeln!(&self.f, "{}", cargo_metadata_fn(self))?;

[baoyachi]

@mchodzikiewicz

1. Using no_std requires adding a check in the GitHub action, which is currently missing
2. For parts that do not support no_std, consider using feature management

[mchodzikiewicz]

Thanks, that's how I do it (still wip, but I have good progress)

Do you mind if I move main crate content to shadow-rs/ and add it to the workspace along with shadow-rs-consumer that contains shadow!() macro?

This way it is possible to cleanly define what is and what isn't a workspace member which is necessary for no_std example (because workspace feature resolver enables all features required by any member to all other members and no_std requires default-features = false.

As a sidenote, workspace Cargo.toml is pretty "special" and doesn't like to be a manifest for a crate at the same time and it works by chance. (https://doc.rust-lang.org/cargo/reference/workspaces.html)

Additional property of the no_std feature is that there will be two crates and main one will depend on shadow-rs-consumer (to avoid duplication of the macro)

[mchodzikiewicz]

Hi, any updates on this?