Warn if cli-config is not available at compile time (#2135)

* warn if a package relies on the CLI config, but it is not built with the CLI

* fix default features

---------

Co-authored-by: Jonathan Kelley <jkelleyrtp@gmail.com>

packages/cli-config/Cargo.toml

@@ -22,5 +22,6 @@ tauri-bundler = { version = "=1.4.0", features = ["native-tls-vendored"], option
 tauri-utils = { version = "=1.5.*", optional = true }
 
 [features]
-default = []
+default = ["read-config"]
 cli = ["tauri-bundler", "tauri-utils", "clap", "toml", "cargo_toml"]
+read-config = []

packages/cli-config/build.rs

@@ -0,0 +1,11 @@
+// warn if the "read-config" feature is enabled, but the DIOXUS_CONFIG environment variable is not set
+// This means that some library is trying to access the crate's configuration, but the dioxus CLI was not used to build the application.
+
+fn main() {
+    println!("cargo:rerun-if-env-changed=DIOXUS_CONFIG");
+    let dioxus_config = std::env::var("DIOXUS_CONFIG");
+    let built_with_dioxus = dioxus_config.is_ok();
+    if cfg!(feature = "read-config") && !built_with_dioxus {
+        println!("cargo:warning=A library is trying to access the crate's configuration, but the dioxus CLI was not used to build the application. Information about the Dioxus CLI is available at https://dioxuslabs.com/learn/0.5/CLI/installation");
+    }
+}

packages/cli-config/src/lib.rs

@@ -42,6 +42,7 @@ impl std::fmt::Display for DioxusCLINotUsed {
 
 impl std::error::Error for DioxusCLINotUsed {}
 
+#[cfg(feature = "read-config")]
 /// The current crate's configuration.
 pub static CURRENT_CONFIG: once_cell::sync::Lazy<
     Result<crate::config::CrateConfig, DioxusCLINotUsed>,
@@ -54,5 +55,6 @@ pub static CURRENT_CONFIG: once_cell::sync::Lazy<
     })
 });
 
+#[cfg(feature = "read-config")]
 /// The current crate's configuration.
 pub const CURRENT_CONFIG_JSON: Option<&str> = std::option_env!("DIOXUS_CONFIG");