cxx-qt-gen: require cxx_file_stem until Span::source_file is stable

Closes KDAB#855

CHANGELOG.md

@@ -36,6 +36,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `#[qobject]` attribute is now optional on types in `extern "RustQt"`
 - `#[qobject]` attribute is now required on types in `extern "C++Qt"`
 - Folder structure of Rust bridges is now considered in the same way as CXX in `CxxQtBuilder`
+- All `#[cxx_qt::bridge]` macros must specify a `cxx_file_stem` until `Span::source_file()` is stable
 
 ### Fixed
 

book/src/bridge/extern_rustqt.md

@@ -23,7 +23,9 @@ mod ffi {
 
 The `extern "RustQt"` section of a CXX bridge declares Rust types and signatures to be made available to Qt and C++.
 
-The CXX code generator uses your `extern "Rust"` section(s) to produce a C++ header file containing the corresponding C++ declarations. The generated header has a file name matching the module ident or the `cxx_file_stem` field in the `#[cxx_qt::bridge]` attribute and with a `.cxxqt.h` file extension.
+The CXX code generator uses your `extern "Rust"` section(s) to produce a C++ header file containing the corresponding C++ declarations. The generated header has a file name of the `cxx_file_stem` field in the `#[cxx_qt::bridge]` attribute and with a `.cxxqt.h` file extension.
+
+> Note that once there is support for `source_file` or similar in the `Span` macro we want to support copying the file name like CXX.
 
 A bridge module may contain zero or more `extern "RustQt"` blocks.
 

book/src/bridge/index.md

@@ -30,7 +30,7 @@ By default, the name of the generated C++ header file will be the name of the mo
 
 This can cause issues as the module is normally called `ffi` or `qobject`, so collisions would occur.
 
-The `cxx_file_stem` option allow a file name to be specified to avoid collisions.
+The `cxx_file_stem` option allows a file name to be specified to avoid collisions.
 
 ```rust,ignore
 {{#include ../../../examples/qml_features/rust/src/types.rs:book_cxx_file_stem}}

book/src/getting-started/5-cmake-integration.md

@@ -38,11 +38,15 @@ You can add as much C++ code as you want in addition to this.
 
 For every `#[cxx_qt::bridge]` that we define in Rust, CXX-Qt will generate a corresponding C++ header file.
 They will always be in the `cxx-qt-gen/` include path and use the snake_case naming convention.
-The name of the header file will be the name of the Rust module of your `#[cxx_qt::bridge]`, followed by `.cxxqt.h`.
-So in our case: `#include cxx-qt-gen/qobject.cxxqt.h`
+The name of the header file will be the `cxx_file_stem` of your `#[cxx_qt::bridge]`, followed by `.cxxqt.h`.
+So in our case: `#include cxx-qt-gen/src/cxxqt_object.cxxqt.h`
 
 > Note that the [`cxx_file_stem`](../bridge/index.md#cxx_file_stem) option can be specified in the bridge macro to choose the file name.
 
+> Note that once `Span::source_file()` is stable the `cxx_file_stem` will be optional and the file name will be the default like CXX>
+
+> Note any folders relative to the fargo manifest are considered hence the `src` folder.
+
 Including the generated header allows accessing the `MyObject` C++ class, just like any other C++ class.
 Inherit from it, connect signals and slots to it, put it in a QVector, do whatever you want with it.
 That's the power of CXX-Qt.

crates/cxx-qt-build/src/lib.rs

@@ -130,13 +130,9 @@ impl GeneratedCpp {
                         .map_err(to_diagnostic)?;
                     let rust_tokens = write_rust(&generated_rust);
                     // Use the relative path with the cxx_file_stem
-                    //
-                    // TODO: ideally CXX-Qt would also use the file name
-                    // but it uses the module or cxx_file_stem for now
-                    // https://github.com/KDAB/cxx-qt/pull/200/commits/4861c92e66c3a022d3f0dedd9f8fd20db064b42b
                     file_ident = relative_path
                         .as_ref()
-                        .with_file_name(parser.cxx_file_stem)
+                        .with_file_name(parser.cxx_file_stem())
                         .to_str()
                         .unwrap()
                         .to_owned();

crates/cxx-qt-gen/src/generator/cpp/mod.rs

@@ -59,7 +59,7 @@ impl GeneratedCppBlocks {
         Ok(GeneratedCppBlocks {
             forward_declares,
             includes,
-            cxx_file_stem: parser.cxx_file_stem.clone(),
+            cxx_file_stem: parser.cxx_file_stem(),
             qobjects: parser
                 .cxx_qt_data
                 .qobjects
@@ -86,7 +86,7 @@ mod tests {
     #[test]
     fn test_generated_cpp_blocks() {
         let module: ItemMod = parse_quote! {
-            #[cxx_qt::bridge]
+            #[cxx_qt::bridge(cxx_file_stem = "ffi")]
             mod ffi {
                 extern "RustQt" {
                     #[qobject]
@@ -124,7 +124,7 @@ mod tests {
     #[test]
     fn test_generated_cpp_blocks_namespace() {
         let module: ItemMod = parse_quote! {
-            #[cxx_qt::bridge(namespace = "cxx_qt")]
+            #[cxx_qt::bridge(cxx_file_stem = "ffi", namespace = "cxx_qt")]
             mod ffi {
                 extern "RustQt" {
                     #[qobject]

crates/cxx-qt-gen/src/generator/rust/mod.rs

@@ -79,7 +79,7 @@ impl GeneratedRustBlocks {
 
 /// Generate the include line for this parsed block
 fn generate_include(parser: &Parser) -> Result<Item> {
-    let import_path = format!("{}.cxxqt.h", parser.cxx_file_stem);
+    let import_path = format!("{}.cxxqt.h", parser.cxx_file_stem());
 
     syn::parse2(quote! {
         unsafe extern "C++" {

crates/cxx-qt-gen/src/parser/mod.rs

@@ -36,13 +36,13 @@ pub struct Parser {
     /// all type names that were found in this module, including CXX types
     pub(crate) type_names: TypeNames,
     /// The stem of the file that the CXX headers for this module will be generated into
-    pub cxx_file_stem: String,
+    pub(crate) cxx_file_stem: Option<String>,
 }
 
 impl Parser {
-    fn parse_mod_attributes(module: &mut ItemMod) -> Result<(Option<String>, String)> {
+    fn parse_mod_attributes(module: &mut ItemMod) -> Result<(Option<String>, Option<String>)> {
         let mut namespace = None;
-        let mut cxx_file_stem = module.ident.to_string();
+        let mut cxx_file_stem = None;
 
         // Remove the cxx_qt::bridge attribute
         if let Some(attr) = attribute_take_path(&mut module.attrs, &["cxx_qt", "bridge"]) {
@@ -58,13 +58,21 @@ impl Parser {
                                 namespace = Some(expr_to_string(&name_value.value)?);
                             // Parse any custom file stem
                             } else if name_value.path.is_ident("cxx_file_stem") {
-                                cxx_file_stem = expr_to_string(&name_value.value)?;
+                                cxx_file_stem = Some(expr_to_string(&name_value.value)?);
                             }
                         }
                         _others => {}
                     }
                 }
             }
+
+            // Temporary until Span::source_file() is stable
+            if cxx_file_stem.is_none() {
+                return Err(Error::new(
+                    module.span(),
+                    "All cxx_qt::bridge macros specify a cxx_file_stem until Span::source_file() is stable https://github.com/rust-lang/rust/issues/54725",
+                ));
+            }
         } else {
             return Err(Error::new(
                 module.span(),
@@ -127,6 +135,17 @@ impl Parser {
             cxx_file_stem,
         })
     }
+
+    /// Determine the file stem to use for this macro
+    pub fn cxx_file_stem(&self) -> String {
+        if let Some(cxx_file_stem) = self.cxx_file_stem.as_ref() {
+            cxx_file_stem.clone()
+        } else {
+            // TODO: ideally CXX-Qt would also use the file name but it uses the cxx_file_stem for now
+            // https://github.com/KDAB/cxx-qt/pull/200/commits/4861c92e66c3a022d3f0dedd9f8fd20db064b42b
+            unimplemented!("Missing cxx_file_stem, once Span::source_file() is stable we can determine the file name")
+        }
+    }
 }
 
 #[cfg(test)]

examples/qml_minimal/rust/src/cxxqt_object.rs

@@ -9,7 +9,7 @@
 // ANCHOR: book_bridge_macro
 
 /// The bridge definition for our QObject
-#[cxx_qt::bridge]
+#[cxx_qt::bridge(cxx_file_stem = "cxxqt_object")]
 pub mod qobject {
     // ANCHOR_END: book_bridge_macro