Add #[builder(crate = "...")] for re-export scenarios

derive_builder/CHANGELOG.md

@@ -4,6 +4,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 ## Unreleased
 - Produce error when `default` is used with `field(type = "...")` rather than silently ignoring `default` #269
+- Add support for `crate = "..."` to support re-export scenarios #274
 
 ## [0.11.2] - 2022-04-20
 - Allow restricted visibility using `vis = "..."` for builders, build methods, setters, and fields #247

derive_builder/README.md

@@ -130,6 +130,7 @@ It's as simple as three steps:
 - **Builder derivations**: You can use `#[builder(derive(Trait1, Trait2, ...))]` to have the builder derive additonal traits. All builders derive `Default` and `Clone`, so you should not declare those in this attribute.
 - **Pass-through attributes**: Use `#[builder_struct_attr(...)]`, `#[builder_impl_attr(...)]`, `#[builder_field_attr(...)]`, and `#[builder_setter_attr(...)]` to declare attributes that will be added to the relevant part of the generated builder.
 - **no_std support**: Just add `#[builder(no_std)]` to your struct and add `extern crate alloc` to your crate.
+- **Re-export support**: Use `#[builder(crate = "...")]` to set the root for `derive_builder`. This is useful if your crate is re-exporting `derive_builder::Builder` and needs the generated code to not directly reference the `derive_builder` crate.
 
 For more information and examples please take a look at our [documentation][doc].
 

derive_builder/tests/compile-fail/crate_root.rs

@@ -0,0 +1,16 @@
+#[macro_use]
+extern crate derive_builder;
+
+// This is a stand-in for any bad crate directive
+mod empty {}
+
+#[derive(Builder)]
+// It would be nice if the "failed to resolve" errors would identify `"empty"` as the error span,
+// but doing so would require rewriting a lot of the code generation to use the crate_root span
+// for the full path of the thing being imported, and that doesn't seem worth the code churn.
+#[builder(crate = "empty")]
+struct BadCrate {
+    lorem: String,
+}
+
+fn main() {}

derive_builder/tests/compile-fail/crate_root.stderr

@@ -0,0 +1,97 @@
+error[E0433]: failed to resolve: could not find `export` in `empty`
+ --> tests/compile-fail/crate_root.rs:7:10
+  |
+7 | #[derive(Builder)]
+  |          ^^^^^^^ could not find `export` in `empty`
+  |
+  = note: this error originates in the derive macro `Builder` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0433]: failed to resolve: could not find `export` in `empty`
+ --> tests/compile-fail/crate_root.rs:7:10
+  |
+7 | #[derive(Builder)]
+  |          ^^^^^^^ not found in `empty::export::core::option`
+  |
+  = note: this error originates in the derive macro `Builder` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider importing this enum
+  |
+5 | use derive_builder::export::core::option::Option;
+  |
+
+error[E0433]: failed to resolve: could not find `export` in `empty`
+ --> tests/compile-fail/crate_root.rs:7:10
+  |
+7 | #[derive(Builder)]
+  |          ^^^^^^^ not found in `empty::export::core::clone`
+  |
+  = note: this error originates in the derive macro `Builder` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider importing this trait
+  |
+5 | use derive_builder::export::core::clone::Clone;
+  |
+
+error[E0433]: failed to resolve: could not find `export` in `empty`
+ --> tests/compile-fail/crate_root.rs:7:10
+  |
+7 | #[derive(Builder)]
+  |          ^^^^^^^ not found in `empty::export::core::result`
+  |
+  = note: this error originates in the derive macro `Builder` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider importing one of these items
+  |
+5 | use derive_builder::export::core::fmt::Result;
+  |
+5 | use derive_builder::export::core::io::Result;
+  |
+5 | use derive_builder::export::core::result::Result;
+  |
+5 | use derive_builder::export::core::thread::Result;
+  |
+
+error[E0433]: failed to resolve: could not find `export` in `empty`
+ --> tests/compile-fail/crate_root.rs:7:10
+  |
+7 | #[derive(Builder)]
+  |          ^^^^^^^ not found in `empty::export::core::convert`
+  |
+  = note: this error originates in the derive macro `Builder` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider importing this trait
+  |
+5 | use derive_builder::export::core::convert::Into;
+  |
+
+error[E0433]: failed to resolve: could not find `UninitializedFieldError` in `empty`
+ --> tests/compile-fail/crate_root.rs:7:10
+  |
+7 | #[derive(Builder)]
+  |          ^^^^^^^ not found in `empty`
+  |
+  = note: this error originates in the derive macro `Builder` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider importing this struct
+  |
+5 | use derive_builder::UninitializedFieldError;
+  |
+
+error[E0433]: failed to resolve: could not find `export` in `empty`
+ --> tests/compile-fail/crate_root.rs:7:10
+  |
+7 | #[derive(Builder)]
+  |          ^^^^^^^ not found in `empty::export::core::default`
+  |
+  = note: this error originates in the derive macro `Builder` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider importing this trait
+  |
+5 | use derive_builder::export::core::default::Default;
+  |
+
+error[E0412]: cannot find type `UninitializedFieldError` in module `empty`
+ --> tests/compile-fail/crate_root.rs:7:10
+  |
+7 | #[derive(Builder)]
+  |          ^^^^^^^ not found in `empty`
+  |
+  = note: this error originates in the derive macro `Builder` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider importing this struct
+  |
+5 | use derive_builder::UninitializedFieldError;
+  |

derive_builder/tests/run-pass/crate_alias.rs

@@ -0,0 +1,24 @@
+//! Test that an alias of derive_builder is valid in #[builder(crate = "...")]
+//!
+//! This test is imperfect, as it still passes without setting `crate = "..."`.
+//! This is likely because `derive_builder` is automatically present in 2018
+//! without needing the extern crate line.
+//!
+//! The test will fail if an incorrect alias is used, so it adds limited value.
+
+#[macro_use]
+extern crate derive_builder as db;
+
+#[derive(Builder)]
+#[builder(crate = "db")]
+struct AliasedCrate {
+    #[builder(setter(into))]
+    lorem: String,
+}
+
+fn main() {
+    AliasedCrateBuilder::default()
+        .lorem("hello")
+        .build()
+        .unwrap();
+}

derive_builder_core/src/build_method.rs

@@ -40,6 +40,8 @@ use crate::DefaultExpression;
 /// ```
 #[derive(Debug)]
 pub struct BuildMethod<'a> {
+    /// Path to the root of the derive_builder crate.
+    pub crate_root: &'a syn::Path,
     /// Enables code generation for this build method.
     pub enabled: bool,
     /// Name of this build fn.
@@ -82,6 +84,7 @@ impl<'a> ToTokens for BuildMethod<'a> {
         };
         let doc_comment = &self.doc_comment;
         let default_struct = self.default_struct.as_ref().map(|default_expr| {
+            let default_expr = default_expr.with_crate_root(self.crate_root);
             let ident = syn::Ident::new(DEFAULT_STRUCT_NAME, Span::call_site());
             quote!(let #ident: #target_ty #target_ty_generics = #default_expr;)
         });
@@ -92,10 +95,11 @@ impl<'a> ToTokens for BuildMethod<'a> {
         let error_ty = &self.error_ty;
 
         if self.enabled {
+            let crate_root = &self.crate_root;
             tokens.append_all(quote!(
                 #doc_comment
                 #vis fn #ident(#self_param)
-                    -> ::derive_builder::export::core::result::Result<#target_ty #target_ty_generics, #error_ty>
+                    -> #crate_root::export::core::result::Result<#target_ty #target_ty_generics, #error_ty>
                 {
                     #validate_fn
                     #default_struct
@@ -138,6 +142,9 @@ impl<'a> BuildMethod<'a> {
 macro_rules! default_build_method {
     () => {
         BuildMethod {
+            // Deliberately don't use the default value here - make sure
+            // that all test cases are passing crate_root through properly.
+            crate_root: &parse_quote!(::db),
             enabled: true,
             ident: &syn::Ident::new("build", ::proc_macro2::Span::call_site()),
             visibility: ::std::borrow::Cow::Owned(syn::parse_quote!(pub)),
@@ -166,7 +173,7 @@ mod tests {
         assert_eq!(
             quote!(#build_method).to_string(),
             quote!(
-                pub fn build(&self) -> ::derive_builder::export::core::result::Result<Foo, FooBuilderError> {
+                pub fn build(&self) -> ::db::export::core::result::Result<Foo, FooBuilderError> {
                     Ok(Foo {
                         foo: self.foo,
                     })
@@ -187,7 +194,7 @@ mod tests {
         assert_eq!(
             quote!(#build_method).to_string(),
             quote!(
-                pub fn build(&self) -> ::derive_builder::export::core::result::Result<Foo, FooBuilderError> {
+                pub fn build(&self) -> ::db::export::core::result::Result<Foo, FooBuilderError> {
                     let __default: Foo = { Default::default() };
                     Ok(Foo {
                         foo: self.foo,
@@ -217,7 +224,7 @@ mod tests {
         assert_eq!(
             quote!(#build_method).to_string(),
             quote!(
-                pub fn finish(&self) -> ::derive_builder::export::core::result::Result<Foo, FooBuilderError> {
+                pub fn finish(&self) -> ::db::export::core::result::Result<Foo, FooBuilderError> {
                     Ok(Foo {
                         foo: self.foo,
                     })
@@ -238,7 +245,7 @@ mod tests {
         assert_eq!(
             quote!(#build_method).to_string(),
             quote!(
-                pub fn build(&self) -> ::derive_builder::export::core::result::Result<Foo, FooBuilderError> {
+                pub fn build(&self) -> ::db::export::core::result::Result<Foo, FooBuilderError> {
                     IpsumBuilder::validate(&self)?;
 
                     Ok(Foo {