[rust] Add use declarations to Rust-generated bindings for imported FB definitions (#5645)

* Bugfix for Rust generation of union fields named with language keywords

Looking at ParseField, it appears that in the case of unions, an extra field with a `UnionTypeFieldSuffix` is added to the type definition, however, if the name of this field is a keyword in the target language, it isn't escaped.

For example, if generating code for rust for a union field named `type`, flatc will generate a (non-keyword escaped) field named `type_type` for this hidden union field, and one (keyword escaped) called `type_` for the actual union contents.

When the union accessors are generated, they refer to this `type_type` field, but they will escape it mistakenly, generating code like this:

```
  #[inline]
  #[allow(non_snake_case)]
  pub fn type__as_int(&self) -> Option<Int<'a>> {
    if self.type__type() == Type::Int {
      self.type_().map(|u| Int::init_from_table(u))
    } else {
      None
    }
  }
```

Which will fail to build because the field is called `self.type_type()`, not `self.type__type()`.

* [Rust] Add crate-relative use statements for FBS includes.

At present if a flatbuffer description includes a reference to a type in
another file, the generated Rust code needs to be hand-modified to add
the appropriate `use` statements.

This assumes that the dependencies are built into the same crate, which
I think is a reasonable assumption?

* Revert "[Rust] Add crate-relative use statements for FBS includes."

This reverts commit d554d79fec.

* Add updated generated test files.

* Fixing Rust test harness to handle new includes.

Test binaries need to add references to generated code that's
transitively included.

This also has the knock-on in that this code (which is referenced by
include directives directly in the flatbuffer schema files) also needs
to be generated, hence the changes to generate_code.sh.

* Test harnesses expect test data to be checked in.

Put include_test2 files into the same directory as the include_test2
schema definition.

Update all code generation scripts (forgot the batch file from last
time).

Path updates in Rust test.

* Include updated generated code

* Address comments raised in PR

* Fix failing Rust tests.

* Previous merge clobbered this branch change.

* Add updated imports to benchmarks.

* Clarifying comment per PR request

* Update documentation comments per feedback

* Remove non-Rust generated files for include tests, per feedback from @rw/@aardappel

* Broken code generation batch file

* Fix typo

* Add TODO for tidying up use declaration traversal sometime in the future

* Update test files.

src/idl_gen_rust.cpp

@@ -1763,6 +1763,14 @@ class RustGenerator : public BaseGenerator {
   void GenNamespaceImports(const int white_spaces) {
     std::string indent = std::string(white_spaces, ' ');
     code_ += "";
+    for (auto it = parser_.included_files_.begin();
+        it != parser_.included_files_.end(); ++it) {
+      if (it->second.empty()) continue;
+      auto noext = flatbuffers::StripExtension(it->second);
+      auto basename = flatbuffers::StripPath(noext);
+
+      code_ += indent + "use crate::" + basename + "_generated::*;";
+    }
     code_ += indent + "use std::mem;";
     code_ += indent + "use std::cmp::Ordering;";
     code_ += "";
@@ -1847,3 +1855,7 @@ std::string RustMakeRule(const Parser &parser, const std::string &path,
 // TODO(maxburke): There should be test schemas added that use language
 //           keywords as fields of structs, tables, unions, enums, to make sure
 //           that internal code generated references escaped names correctly.
+// TODO(maxburke): We should see if there is a more flexible way of resolving
+//           module paths for use declarations. Right now if schemas refer to
+//           other flatbuffer files, the include paths in emitted Rust bindings
+//           are crate-relative which may undesirable.

tests/generate_code.bat

@@ -40,6 +40,8 @@ set TEST_NOINCL_FLAGS=%TEST_BASE_FLAGS% --no-includes --no-fb-import
 %TEST_NOINCL_FLAGS% %TEST_CPP_FLAGS% -o namespace_test namespace_test/namespace_test1.fbs namespace_test/namespace_test2.fbs || goto FAIL
 
 ..\%buildtype%\flatc.exe --cpp --java --csharp --js --ts --php %TEST_BASE_FLAGS% %TEST_CPP_FLAGS% -o union_vector ./union_vector/union_vector.fbs || goto FAIL
+..\%buildtype%\flatc.exe --rust -I include_test -o include_test include_test/include_test1.fbs || goto FAIL
+..\%buildtype%\flatc.exe --rust -I include_test -o include_test/sub include_test/sub/include_test2.fbs || goto FAIL
 ..\%buildtype%\flatc.exe -b --schema --bfbs-comments --bfbs-builtins -I include_test monster_test.fbs || goto FAIL
 ..\%buildtype%\flatc.exe -b --schema --bfbs-comments --bfbs-builtins -I include_test arrays_test.fbs || goto FAIL
 ..\%buildtype%\flatc.exe --jsonschema --schema -I include_test monster_test.fbs || goto FAIL

tests/generate_code.sh

@@ -37,6 +37,8 @@ $TEST_NOINCL_FLAGS $TEST_CPP_FLAGS -I include_test monster_test.fbs monsterdata_
 $TEST_NOINCL_FLAGS $TEST_CPP_FLAGS -o namespace_test namespace_test/namespace_test1.fbs namespace_test/namespace_test2.fbs
 
 ../flatc --cpp --java --kotlin --csharp --js --ts --php $TEST_BASE_FLAGS $TEST_CPP_FLAGS -o union_vector ./union_vector/union_vector.fbs
+../flatc --rust -I include_test -o include_test include_test/include_test1.fbs
+../flatc --rust -I include_test -o include_test/sub include_test/sub/include_test2.fbs
 ../flatc -b --schema --bfbs-comments --bfbs-builtins -I include_test monster_test.fbs
 ../flatc -b --schema --bfbs-comments --bfbs-builtins -I include_test arrays_test.fbs
 ../flatc --jsonschema --schema -I include_test monster_test.fbs

tests/include_test/include_test1_generated.rs

@@ -0,0 +1,87 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+
+
+use crate::include_test2_generated::*;
+use std::mem;
+use std::cmp::Ordering;
+
+extern crate flatbuffers;
+use self::flatbuffers::EndianScalar;
+
+pub enum TableAOffset {}
+#[derive(Copy, Clone, Debug, PartialEq)]
+
+pub struct TableA<'a> {
+  pub _tab: flatbuffers::Table<'a>,
+}
+
+impl<'a> flatbuffers::Follow<'a> for TableA<'a> {
+    type Inner = TableA<'a>;
+    #[inline]
+    fn follow(buf: &'a [u8], loc: usize) -> Self::Inner {
+        Self {
+            _tab: flatbuffers::Table { buf: buf, loc: loc },
+        }
+    }
+}
+
+impl<'a> TableA<'a> {
+    #[inline]
+    pub fn init_from_table(table: flatbuffers::Table<'a>) -> Self {
+        TableA {
+            _tab: table,
+        }
+    }
+    #[allow(unused_mut)]
+    pub fn create<'bldr: 'args, 'args: 'mut_bldr, 'mut_bldr>(
+        _fbb: &'mut_bldr mut flatbuffers::FlatBufferBuilder<'bldr>,
+        args: &'args TableAArgs<'args>) -> flatbuffers::WIPOffset<TableA<'bldr>> {
+      let mut builder = TableABuilder::new(_fbb);
+      if let Some(x) = args.b { builder.add_b(x); }
+      builder.finish()
+    }
+
+    pub const VT_B: flatbuffers::VOffsetT = 4;
+
+  #[inline]
+  pub fn b(&self) -> Option<my_game::other_name_space::TableB<'a>> {
+    self._tab.get::<flatbuffers::ForwardsUOffset<my_game::other_name_space::TableB<'a>>>(TableA::VT_B, None)
+  }
+}
+
+pub struct TableAArgs<'a> {
+    pub b: Option<flatbuffers::WIPOffset<my_game::other_name_space::TableB<'a >>>,
+}
+impl<'a> Default for TableAArgs<'a> {
+    #[inline]
+    fn default() -> Self {
+        TableAArgs {
+            b: None,
+        }
+    }
+}
+pub struct TableABuilder<'a: 'b, 'b> {
+  fbb_: &'b mut flatbuffers::FlatBufferBuilder<'a>,
+  start_: flatbuffers::WIPOffset<flatbuffers::TableUnfinishedWIPOffset>,
+}
+impl<'a: 'b, 'b> TableABuilder<'a, 'b> {
+  #[inline]
+  pub fn add_b(&mut self, b: flatbuffers::WIPOffset<my_game::other_name_space::TableB<'b >>) {
+    self.fbb_.push_slot_always::<flatbuffers::WIPOffset<my_game::other_name_space::TableB>>(TableA::VT_B, b);
+  }
+  #[inline]
+  pub fn new(_fbb: &'b mut flatbuffers::FlatBufferBuilder<'a>) -> TableABuilder<'a, 'b> {
+    let start = _fbb.start_table();
+    TableABuilder {
+      fbb_: _fbb,
+      start_: start,
+    }
+  }
+  #[inline]
+  pub fn finish(self) -> flatbuffers::WIPOffset<TableA<'a>> {
+    let o = self.fbb_.end_table(self.start_);
+    flatbuffers::WIPOffset::new(o.value())
+  }
+}
+

tests/include_test/sub/include_test2_generated.rs

@@ -0,0 +1,222 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+
+
+use crate::include_test1_generated::*;
+use std::mem;
+use std::cmp::Ordering;
+
+extern crate flatbuffers;
+use self::flatbuffers::EndianScalar;
+
+#[allow(unused_imports, dead_code)]
+pub mod my_game {
+
+  use crate::include_test1_generated::*;
+  use std::mem;
+  use std::cmp::Ordering;
+
+  extern crate flatbuffers;
+  use self::flatbuffers::EndianScalar;
+#[allow(unused_imports, dead_code)]
+pub mod other_name_space {
+
+  use crate::include_test1_generated::*;
+  use std::mem;
+  use std::cmp::Ordering;
+
+  extern crate flatbuffers;
+  use self::flatbuffers::EndianScalar;
+
+#[allow(non_camel_case_types)]
+#[repr(i64)]
+#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
+pub enum FromInclude {
+  IncludeVal = 0,
+
+}
+
+pub const ENUM_MIN_FROM_INCLUDE: i64 = 0;
+pub const ENUM_MAX_FROM_INCLUDE: i64 = 0;
+
+impl<'a> flatbuffers::Follow<'a> for FromInclude {
+  type Inner = Self;
+  #[inline]
+  fn follow(buf: &'a [u8], loc: usize) -> Self::Inner {
+    flatbuffers::read_scalar_at::<Self>(buf, loc)
+  }
+}
+
+impl flatbuffers::EndianScalar for FromInclude {
+  #[inline]
+  fn to_little_endian(self) -> Self {
+    let n = i64::to_le(self as i64);
+    let p = &n as *const i64 as *const FromInclude;
+    unsafe { *p }
+  }
+  #[inline]
+  fn from_little_endian(self) -> Self {
+    let n = i64::from_le(self as i64);
+    let p = &n as *const i64 as *const FromInclude;
+    unsafe { *p }
+  }
+}
+
+impl flatbuffers::Push for FromInclude {
+    type Output = FromInclude;
+    #[inline]
+    fn push(&self, dst: &mut [u8], _rest: &[u8]) {
+        flatbuffers::emplace_scalar::<FromInclude>(dst, *self);
+    }
+}
+
+#[allow(non_camel_case_types)]
+pub const ENUM_VALUES_FROM_INCLUDE:[FromInclude; 1] = [
+  FromInclude::IncludeVal
+];
+
+#[allow(non_camel_case_types)]
+pub const ENUM_NAMES_FROM_INCLUDE:[&'static str; 1] = [
+    "IncludeVal"
+];
+
+pub fn enum_name_from_include(e: FromInclude) -> &'static str {
+  let index = e as i64;
+  ENUM_NAMES_FROM_INCLUDE[index as usize]
+}
+
+// struct Unused, aligned to 4
+#[repr(C, align(4))]
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct Unused {
+  a_: i32,
+} // pub struct Unused
+impl flatbuffers::SafeSliceAccess for Unused {}
+impl<'a> flatbuffers::Follow<'a> for Unused {
+  type Inner = &'a Unused;
+  #[inline]
+  fn follow(buf: &'a [u8], loc: usize) -> Self::Inner {
+    <&'a Unused>::follow(buf, loc)
+  }
+}
+impl<'a> flatbuffers::Follow<'a> for &'a Unused {
+  type Inner = &'a Unused;
+  #[inline]
+  fn follow(buf: &'a [u8], loc: usize) -> Self::Inner {
+    flatbuffers::follow_cast_ref::<Unused>(buf, loc)
+  }
+}
+impl<'b> flatbuffers::Push for Unused {
+    type Output = Unused;
+    #[inline]
+    fn push(&self, dst: &mut [u8], _rest: &[u8]) {
+        let src = unsafe {
+            ::std::slice::from_raw_parts(self as *const Unused as *const u8, Self::size())
+        };
+        dst.copy_from_slice(src);
+    }
+}
+impl<'b> flatbuffers::Push for &'b Unused {
+    type Output = Unused;
+
+    #[inline]
+    fn push(&self, dst: &mut [u8], _rest: &[u8]) {
+        let src = unsafe {
+            ::std::slice::from_raw_parts(*self as *const Unused as *const u8, Self::size())
+        };
+        dst.copy_from_slice(src);
+    }
+}
+
+
+impl Unused {
+  pub fn new<'a>(_a: i32) -> Self {
+    Unused {
+      a_: _a.to_little_endian(),
+
+    }
+  }
+  pub fn a<'a>(&'a self) -> i32 {
+    self.a_.from_little_endian()
+  }
+}
+
+pub enum TableBOffset {}
+#[derive(Copy, Clone, Debug, PartialEq)]
+
+pub struct TableB<'a> {
+  pub _tab: flatbuffers::Table<'a>,
+}
+
+impl<'a> flatbuffers::Follow<'a> for TableB<'a> {
+    type Inner = TableB<'a>;
+    #[inline]
+    fn follow(buf: &'a [u8], loc: usize) -> Self::Inner {
+        Self {
+            _tab: flatbuffers::Table { buf: buf, loc: loc },
+        }
+    }
+}
+
+impl<'a> TableB<'a> {
+    #[inline]
+    pub fn init_from_table(table: flatbuffers::Table<'a>) -> Self {
+        TableB {
+            _tab: table,
+        }
+    }
+    #[allow(unused_mut)]
+    pub fn create<'bldr: 'args, 'args: 'mut_bldr, 'mut_bldr>(
+        _fbb: &'mut_bldr mut flatbuffers::FlatBufferBuilder<'bldr>,
+        args: &'args TableBArgs<'args>) -> flatbuffers::WIPOffset<TableB<'bldr>> {
+      let mut builder = TableBBuilder::new(_fbb);
+      if let Some(x) = args.a { builder.add_a(x); }
+      builder.finish()
+    }
+
+    pub const VT_A: flatbuffers::VOffsetT = 4;
+
+  #[inline]
+  pub fn a(&self) -> Option<super::super::TableA<'a>> {
+    self._tab.get::<flatbuffers::ForwardsUOffset<super::super::TableA<'a>>>(TableB::VT_A, None)
+  }
+}
+
+pub struct TableBArgs<'a> {
+    pub a: Option<flatbuffers::WIPOffset<super::super::TableA<'a >>>,
+}
+impl<'a> Default for TableBArgs<'a> {
+    #[inline]
+    fn default() -> Self {
+        TableBArgs {
+            a: None,
+        }
+    }
+}
+pub struct TableBBuilder<'a: 'b, 'b> {
+  fbb_: &'b mut flatbuffers::FlatBufferBuilder<'a>,
+  start_: flatbuffers::WIPOffset<flatbuffers::TableUnfinishedWIPOffset>,
+}
+impl<'a: 'b, 'b> TableBBuilder<'a, 'b> {
+  #[inline]
+  pub fn add_a(&mut self, a: flatbuffers::WIPOffset<super::super::TableA<'b >>) {
+    self.fbb_.push_slot_always::<flatbuffers::WIPOffset<super::super::TableA>>(TableB::VT_A, a);
+  }
+  #[inline]
+  pub fn new(_fbb: &'b mut flatbuffers::FlatBufferBuilder<'a>) -> TableBBuilder<'a, 'b> {
+    let start = _fbb.start_table();
+    TableBBuilder {
+      fbb_: _fbb,
+      start_: start,
+    }
+  }
+  #[inline]
+  pub fn finish(self) -> flatbuffers::WIPOffset<TableB<'a>> {
+    let o = self.fbb_.end_table(self.start_);
+    flatbuffers::WIPOffset::new(o.value())
+  }
+}
+
+}  // pub mod OtherNameSpace
+}  // pub mod MyGame
+

tests/monster_test_generated.rs

@@ -2,6 +2,8 @@
 
 
 
+use crate::include_test1_generated::*;
+use crate::include_test2_generated::*;
 use std::mem;
 use std::cmp::Ordering;
 
@@ -11,6 +13,8 @@ use self::flatbuffers::EndianScalar;
 #[allow(unused_imports, dead_code)]
 pub mod my_game {
 
+  use crate::include_test1_generated::*;
+  use crate::include_test2_generated::*;
   use std::mem;
   use std::cmp::Ordering;
 
@@ -83,6 +87,8 @@ impl<'a: 'b, 'b> InParentNamespaceBuilder<'a, 'b> {
 #[allow(unused_imports, dead_code)]
 pub mod example_2 {
 
+  use crate::include_test1_generated::*;
+  use crate::include_test2_generated::*;
   use std::mem;
   use std::cmp::Ordering;
 
@@ -157,6 +163,8 @@ impl<'a: 'b, 'b> MonsterBuilder<'a, 'b> {
 #[allow(unused_imports, dead_code)]
 pub mod example {
 
+  use crate::include_test1_generated::*;
+  use crate::include_test2_generated::*;
   use std::mem;
   use std::cmp::Ordering;
 

tests/namespace_test/namespace_test2_generated.rs

@@ -2,6 +2,7 @@
 
 
 
+use crate::namespace_test1_generated::*;
 use std::mem;
 use std::cmp::Ordering;
 
@@ -11,6 +12,7 @@ use self::flatbuffers::EndianScalar;
 #[allow(unused_imports, dead_code)]
 pub mod namespace_a {
 
+  use crate::namespace_test1_generated::*;
   use std::mem;
   use std::cmp::Ordering;
 
@@ -198,6 +200,7 @@ impl<'a: 'b, 'b> SecondTableInABuilder<'a, 'b> {
 #[allow(unused_imports, dead_code)]
 pub mod namespace_c {
 
+  use crate::namespace_test1_generated::*;
   use std::mem;
   use std::cmp::Ordering;
 

tests/rust_usage_test/benches/flatbuffers_benchmarks.rs

@@ -20,6 +20,14 @@ use bencher::Bencher;
 
 extern crate flatbuffers;
 
+#[allow(dead_code, unused_imports)]
+#[path = "../../include_test/include_test1_generated.rs"]
+pub mod include_test1_generated;
+
+#[allow(dead_code, unused_imports)]
+#[path = "../../include_test/sub/include_test2_generated.rs"]
+pub mod include_test2_generated;
+
 #[allow(dead_code, unused_imports)]
 #[path = "../../monster_test_generated.rs"]
 mod monster_test_generated;

tests/rust_usage_test/bin/alloc_check.rs

@@ -28,6 +28,14 @@ static A: TrackingAllocator = TrackingAllocator;
 
 // import the flatbuffers generated code:
 extern crate flatbuffers;
+#[allow(dead_code, unused_imports)]
+#[path = "../../include_test/include_test1_generated.rs"]
+pub mod include_test1_generated;
+
+#[allow(dead_code, unused_imports)]
+#[path = "../../include_test/sub/include_test2_generated.rs"]
+pub mod include_test2_generated;
+
 #[allow(dead_code, unused_imports)]
 #[path = "../../monster_test_generated.rs"]
 mod monster_test_generated;

tests/rust_usage_test/bin/monster_example.rs

@@ -1,10 +1,19 @@
 extern crate flatbuffers;
 
+#[allow(dead_code, unused_imports)]
+#[path = "../../include_test/include_test1_generated.rs"]
+pub mod include_test1_generated;
+
+#[allow(dead_code, unused_imports)]
+#[path = "../../include_test/sub/include_test2_generated.rs"]
+pub mod include_test2_generated;
+
 #[allow(dead_code, unused_imports)]
 #[path = "../../monster_test_generated.rs"]
 mod monster_test_generated;
 pub use monster_test_generated::my_game;
 
+
 use std::io::Read;
 
 fn main() {

tests/rust_usage_test/tests/integration_test.rs

@@ -19,6 +19,14 @@ extern crate quickcheck;
 
 extern crate flatbuffers;
 
+#[allow(dead_code, unused_imports)]
+#[path = "../../include_test/include_test1_generated.rs"]
+pub mod include_test1_generated;
+
+#[allow(dead_code, unused_imports)]
+#[path = "../../include_test/sub/include_test2_generated.rs"]
+pub mod include_test2_generated;
+
 #[allow(dead_code, unused_imports)]
 #[path = "../../monster_test_generated.rs"]
 mod monster_test_generated;