Rework how Rust generated files are laid out (#6731)

* Refactored Rust Generated code into a module directory.

Each symbol will be generated into one file and then
imported into a module. This breaks the "out_dir"
pattern where some users would generate code in their
target/ directory. Also, these objects are best used
in their own module. It will be hard for users to share
their own module structure with flatbuffers namespaces.

There may be solutions to these drawbacks but that should
be discussed. I don't want to overengineer here.

* shadow error

* try fix .bat file

* fix .bat 2

* Restore accidentally deleted files

* Fixed some DONOTSUBMITs and made Rust outdir pattern use symlinks.

* fixed binary files

* git clang format

* make generated onefiles not public and fix .bat

* reduced diff with master in generate_code.sh

* fix shadowed variable

* add object api flags to .bat

* space

* Removed extern crate and extra &

* use statement

* more clippy lints

* format

* Undo extern crate -> use change, it actually matters to our tests

Co-authored-by: Casper Neo <cneo@google.com>

tests/namespace_test/namespace_a/namespace_b/enum_in_nested_ns_generated.rs

@@ -0,0 +1,97 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+extern crate flatbuffers;
+use std::mem;
+use std::cmp::Ordering;
+use self::flatbuffers::{EndianScalar, Follow};
+use super::*;
+#[deprecated(since = "2.0.0", note = "Use associated constants instead. This will no longer be generated in 2021.")]
+pub const ENUM_MIN_ENUM_IN_NESTED_NS: i8 = 0;
+#[deprecated(since = "2.0.0", note = "Use associated constants instead. This will no longer be generated in 2021.")]
+pub const ENUM_MAX_ENUM_IN_NESTED_NS: i8 = 2;
+#[deprecated(since = "2.0.0", note = "Use associated constants instead. This will no longer be generated in 2021.")]
+#[allow(non_camel_case_types)]
+pub const ENUM_VALUES_ENUM_IN_NESTED_NS: [EnumInNestedNS; 3] = [
+  EnumInNestedNS::A,
+  EnumInNestedNS::B,
+  EnumInNestedNS::C,
+];
+
+#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
+#[repr(transparent)]
+pub struct EnumInNestedNS(pub i8);
+#[allow(non_upper_case_globals)]
+impl EnumInNestedNS {
+  pub const A: Self = Self(0);
+  pub const B: Self = Self(1);
+  pub const C: Self = Self(2);
+
+  pub const ENUM_MIN: i8 = 0;
+  pub const ENUM_MAX: i8 = 2;
+  pub const ENUM_VALUES: &'static [Self] = &[
+    Self::A,
+    Self::B,
+    Self::C,
+  ];
+  /// Returns the variant's name or "" if unknown.
+  pub fn variant_name(self) -> Option<&'static str> {
+    match self {
+      Self::A => Some("A"),
+      Self::B => Some("B"),
+      Self::C => Some("C"),
+      _ => None,
+    }
+  }
+}
+impl std::fmt::Debug for EnumInNestedNS {
+  fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    if let Some(name) = self.variant_name() {
+      f.write_str(name)
+    } else {
+      f.write_fmt(format_args!("<UNKNOWN {:?}>", self.0))
+    }
+  }
+}
+impl<'a> flatbuffers::Follow<'a> for EnumInNestedNS {
+  type Inner = Self;
+  #[inline]
+  fn follow(buf: &'a [u8], loc: usize) -> Self::Inner {
+    let b = unsafe {
+      flatbuffers::read_scalar_at::<i8>(buf, loc)
+    };
+    Self(b)
+  }
+}
+
+impl flatbuffers::Push for EnumInNestedNS {
+    type Output = EnumInNestedNS;
+    #[inline]
+    fn push(&self, dst: &mut [u8], _rest: &[u8]) {
+        unsafe { flatbuffers::emplace_scalar::<i8>(dst, self.0); }
+    }
+}
+
+impl flatbuffers::EndianScalar for EnumInNestedNS {
+  #[inline]
+  fn to_little_endian(self) -> Self {
+    let b = i8::to_le(self.0);
+    Self(b)
+  }
+  #[inline]
+  #[allow(clippy::wrong_self_convention)]
+  fn from_little_endian(self) -> Self {
+    let b = i8::from_le(self.0);
+    Self(b)
+  }
+}
+
+impl<'a> flatbuffers::Verifiable for EnumInNestedNS {
+  #[inline]
+  fn run_verifier(
+    v: &mut flatbuffers::Verifier, pos: usize
+  ) -> Result<(), flatbuffers::InvalidFlatbuffer> {
+    use self::flatbuffers::Verifiable;
+    i8::run_verifier(v, pos)
+  }
+}
+
+impl flatbuffers::SimpleToVerifyInSlice for EnumInNestedNS {}

tests/namespace_test/namespace_a/namespace_b/struct_in_nested_ns_generated.rs

@@ -0,0 +1,155 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+extern crate flatbuffers;
+use std::mem;
+use std::cmp::Ordering;
+use self::flatbuffers::{EndianScalar, Follow};
+use super::*;
+// struct StructInNestedNS, aligned to 4
+#[repr(transparent)]
+#[derive(Clone, Copy, PartialEq)]
+pub struct StructInNestedNS(pub [u8; 8]);
+impl Default for StructInNestedNS { 
+  fn default() -> Self { 
+    Self([0; 8])
+  }
+}
+impl std::fmt::Debug for StructInNestedNS {
+  fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    f.debug_struct("StructInNestedNS")
+      .field("a", &self.a())
+      .field("b", &self.b())
+      .finish()
+  }
+}
+
+impl flatbuffers::SimpleToVerifyInSlice for StructInNestedNS {}
+impl flatbuffers::SafeSliceAccess for StructInNestedNS {}
+impl<'a> flatbuffers::Follow<'a> for StructInNestedNS {
+  type Inner = &'a StructInNestedNS;
+  #[inline]
+  fn follow(buf: &'a [u8], loc: usize) -> Self::Inner {
+    <&'a StructInNestedNS>::follow(buf, loc)
+  }
+}
+impl<'a> flatbuffers::Follow<'a> for &'a StructInNestedNS {
+  type Inner = &'a StructInNestedNS;
+  #[inline]
+  fn follow(buf: &'a [u8], loc: usize) -> Self::Inner {
+    flatbuffers::follow_cast_ref::<StructInNestedNS>(buf, loc)
+  }
+}
+impl<'b> flatbuffers::Push for StructInNestedNS {
+    type Output = StructInNestedNS;
+    #[inline]
+    fn push(&self, dst: &mut [u8], _rest: &[u8]) {
+        let src = unsafe {
+            ::std::slice::from_raw_parts(self as *const StructInNestedNS as *const u8, Self::size())
+        };
+        dst.copy_from_slice(src);
+    }
+}
+impl<'b> flatbuffers::Push for &'b StructInNestedNS {
+    type Output = StructInNestedNS;
+
+    #[inline]
+    fn push(&self, dst: &mut [u8], _rest: &[u8]) {
+        let src = unsafe {
+            ::std::slice::from_raw_parts(*self as *const StructInNestedNS as *const u8, Self::size())
+        };
+        dst.copy_from_slice(src);
+    }
+}
+
+impl<'a> flatbuffers::Verifiable for StructInNestedNS {
+  #[inline]
+  fn run_verifier(
+    v: &mut flatbuffers::Verifier, pos: usize
+  ) -> Result<(), flatbuffers::InvalidFlatbuffer> {
+    use self::flatbuffers::Verifiable;
+    v.in_buffer::<Self>(pos)
+  }
+}
+impl<'a> StructInNestedNS {
+  #[allow(clippy::too_many_arguments)]
+  pub fn new(
+    a: i32,
+    b: i32,
+  ) -> Self {
+    let mut s = Self([0; 8]);
+    s.set_a(a);
+    s.set_b(b);
+    s
+  }
+
+    pub const fn get_fully_qualified_name() -> &'static str {
+        "NamespaceA.NamespaceB.StructInNestedNS"
+    }
+
+  pub fn a(&self) -> i32 {
+    let mut mem = core::mem::MaybeUninit::<i32>::uninit();
+    unsafe {
+      core::ptr::copy_nonoverlapping(
+        self.0[0..].as_ptr(),
+        mem.as_mut_ptr() as *mut u8,
+        core::mem::size_of::<i32>(),
+      );
+      mem.assume_init()
+    }.from_little_endian()
+  }
+
+  pub fn set_a(&mut self, x: i32) {
+    let x_le = x.to_little_endian();
+    unsafe {
+      core::ptr::copy_nonoverlapping(
+        &x_le as *const i32 as *const u8,
+        self.0[0..].as_mut_ptr(),
+        core::mem::size_of::<i32>(),
+      );
+    }
+  }
+
+  pub fn b(&self) -> i32 {
+    let mut mem = core::mem::MaybeUninit::<i32>::uninit();
+    unsafe {
+      core::ptr::copy_nonoverlapping(
+        self.0[4..].as_ptr(),
+        mem.as_mut_ptr() as *mut u8,
+        core::mem::size_of::<i32>(),
+      );
+      mem.assume_init()
+    }.from_little_endian()
+  }
+
+  pub fn set_b(&mut self, x: i32) {
+    let x_le = x.to_little_endian();
+    unsafe {
+      core::ptr::copy_nonoverlapping(
+        &x_le as *const i32 as *const u8,
+        self.0[4..].as_mut_ptr(),
+        core::mem::size_of::<i32>(),
+      );
+    }
+  }
+
+  pub fn unpack(&self) -> StructInNestedNST {
+    StructInNestedNST {
+      a: self.a(),
+      b: self.b(),
+    }
+  }
+}
+
+#[derive(Debug, Clone, PartialEq, Default)]
+pub struct StructInNestedNST {
+  pub a: i32,
+  pub b: i32,
+}
+impl StructInNestedNST {
+  pub fn pack(&self) -> StructInNestedNS {
+    StructInNestedNS::new(
+      self.a,
+      self.b,
+    )
+  }
+}
+

tests/namespace_test/namespace_a/namespace_b/table_in_nested_ns_generated.rs

@@ -0,0 +1,130 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+extern crate flatbuffers;
+use std::mem;
+use std::cmp::Ordering;
+use self::flatbuffers::{EndianScalar, Follow};
+use super::*;
+pub enum TableInNestedNSOffset {}
+#[derive(Copy, Clone, PartialEq)]
+
+pub struct TableInNestedNS<'a> {
+  pub _tab: flatbuffers::Table<'a>,
+}
+
+impl<'a> flatbuffers::Follow<'a> for TableInNestedNS<'a> {
+    type Inner = TableInNestedNS<'a>;
+    #[inline]
+    fn follow(buf: &'a [u8], loc: usize) -> Self::Inner {
+        Self { _tab: flatbuffers::Table { buf, loc } }
+    }
+}
+
+impl<'a> TableInNestedNS<'a> {
+    pub const fn get_fully_qualified_name() -> &'static str {
+        "NamespaceA.NamespaceB.TableInNestedNS"
+    }
+
+    #[inline]
+    pub fn init_from_table(table: flatbuffers::Table<'a>) -> Self {
+        TableInNestedNS { _tab: table }
+    }
+    #[allow(unused_mut)]
+    pub fn create<'bldr: 'args, 'args: 'mut_bldr, 'mut_bldr>(
+        _fbb: &'mut_bldr mut flatbuffers::FlatBufferBuilder<'bldr>,
+        args: &'args TableInNestedNSArgs) -> flatbuffers::WIPOffset<TableInNestedNS<'bldr>> {
+      let mut builder = TableInNestedNSBuilder::new(_fbb);
+      builder.add_foo(args.foo);
+      builder.finish()
+    }
+
+    pub fn unpack(&self) -> TableInNestedNST {
+      let foo = self.foo();
+      TableInNestedNST {
+        foo,
+      }
+    }
+    pub const VT_FOO: flatbuffers::VOffsetT = 4;
+
+  #[inline]
+  pub fn foo(&self) -> i32 {
+    self._tab.get::<i32>(TableInNestedNS::VT_FOO, Some(0)).unwrap()
+  }
+}
+
+impl flatbuffers::Verifiable for TableInNestedNS<'_> {
+  #[inline]
+  fn run_verifier(
+    v: &mut flatbuffers::Verifier, pos: usize
+  ) -> Result<(), flatbuffers::InvalidFlatbuffer> {
+    use self::flatbuffers::Verifiable;
+    v.visit_table(pos)?
+     .visit_field::<i32>("foo", Self::VT_FOO, false)?
+     .finish();
+    Ok(())
+  }
+}
+pub struct TableInNestedNSArgs {
+    pub foo: i32,
+}
+impl<'a> Default for TableInNestedNSArgs {
+    #[inline]
+    fn default() -> Self {
+        TableInNestedNSArgs {
+            foo: 0,
+        }
+    }
+}
+pub struct TableInNestedNSBuilder<'a: 'b, 'b> {
+  fbb_: &'b mut flatbuffers::FlatBufferBuilder<'a>,
+  start_: flatbuffers::WIPOffset<flatbuffers::TableUnfinishedWIPOffset>,
+}
+impl<'a: 'b, 'b> TableInNestedNSBuilder<'a, 'b> {
+  #[inline]
+  pub fn add_foo(&mut self, foo: i32) {
+    self.fbb_.push_slot::<i32>(TableInNestedNS::VT_FOO, foo, 0);
+  }
+  #[inline]
+  pub fn new(_fbb: &'b mut flatbuffers::FlatBufferBuilder<'a>) -> TableInNestedNSBuilder<'a, 'b> {
+    let start = _fbb.start_table();
+    TableInNestedNSBuilder {
+      fbb_: _fbb,
+      start_: start,
+    }
+  }
+  #[inline]
+  pub fn finish(self) -> flatbuffers::WIPOffset<TableInNestedNS<'a>> {
+    let o = self.fbb_.end_table(self.start_);
+    flatbuffers::WIPOffset::new(o.value())
+  }
+}
+
+impl std::fmt::Debug for TableInNestedNS<'_> {
+  fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+    let mut ds = f.debug_struct("TableInNestedNS");
+      ds.field("foo", &self.foo());
+      ds.finish()
+  }
+}
+#[non_exhaustive]
+#[derive(Debug, Clone, PartialEq)]
+pub struct TableInNestedNST {
+  pub foo: i32,
+}
+impl Default for TableInNestedNST {
+  fn default() -> Self {
+    Self {
+      foo: 0,
+    }
+  }
+}
+impl TableInNestedNST {
+  pub fn pack<'b>(
+    &self,
+    _fbb: &mut flatbuffers::FlatBufferBuilder<'b>
+  ) -> flatbuffers::WIPOffset<TableInNestedNS<'b>> {
+    let foo = self.foo;
+    TableInNestedNS::create(_fbb, &TableInNestedNSArgs{
+      foo,
+    })
+  }
+}

tests/namespace_test/namespace_a/namespace_b/union_in_nested_ns_generated.rs

@@ -0,0 +1,142 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+extern crate flatbuffers;
+use std::mem;
+use std::cmp::Ordering;
+use self::flatbuffers::{EndianScalar, Follow};
+use super::*;
+#[deprecated(since = "2.0.0", note = "Use associated constants instead. This will no longer be generated in 2021.")]
+pub const ENUM_MIN_UNION_IN_NESTED_NS: u8 = 0;
+#[deprecated(since = "2.0.0", note = "Use associated constants instead. This will no longer be generated in 2021.")]
+pub const ENUM_MAX_UNION_IN_NESTED_NS: u8 = 1;
+#[deprecated(since = "2.0.0", note = "Use associated constants instead. This will no longer be generated in 2021.")]
+#[allow(non_camel_case_types)]
+pub const ENUM_VALUES_UNION_IN_NESTED_NS: [UnionInNestedNS; 2] = [
+  UnionInNestedNS::NONE,
+  UnionInNestedNS::TableInNestedNS,
+];
+
+#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
+#[repr(transparent)]
+pub struct UnionInNestedNS(pub u8);
+#[allow(non_upper_case_globals)]
+impl UnionInNestedNS {
+  pub const NONE: Self = Self(0);
+  pub const TableInNestedNS: Self = Self(1);
+
+  pub const ENUM_MIN: u8 = 0;
+  pub const ENUM_MAX: u8 = 1;
+  pub const ENUM_VALUES: &'static [Self] = &[
+    Self::NONE,
+    Self::TableInNestedNS,
+  ];
+  /// Returns the variant's name or "" if unknown.
+  pub fn variant_name(self) -> Option<&'static str> {
+    match self {
+      Self::NONE => Some("NONE"),
+      Self::TableInNestedNS => Some("TableInNestedNS"),
+      _ => None,
+    }
+  }
+}
+impl std::fmt::Debug for UnionInNestedNS {
+  fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    if let Some(name) = self.variant_name() {
+      f.write_str(name)
+    } else {
+      f.write_fmt(format_args!("<UNKNOWN {:?}>", self.0))
+    }
+  }
+}
+impl<'a> flatbuffers::Follow<'a> for UnionInNestedNS {
+  type Inner = Self;
+  #[inline]
+  fn follow(buf: &'a [u8], loc: usize) -> Self::Inner {
+    let b = unsafe {
+      flatbuffers::read_scalar_at::<u8>(buf, loc)
+    };
+    Self(b)
+  }
+}
+
+impl flatbuffers::Push for UnionInNestedNS {
+    type Output = UnionInNestedNS;
+    #[inline]
+    fn push(&self, dst: &mut [u8], _rest: &[u8]) {
+        unsafe { flatbuffers::emplace_scalar::<u8>(dst, self.0); }
+    }
+}
+
+impl flatbuffers::EndianScalar for UnionInNestedNS {
+  #[inline]
+  fn to_little_endian(self) -> Self {
+    let b = u8::to_le(self.0);
+    Self(b)
+  }
+  #[inline]
+  #[allow(clippy::wrong_self_convention)]
+  fn from_little_endian(self) -> Self {
+    let b = u8::from_le(self.0);
+    Self(b)
+  }
+}
+
+impl<'a> flatbuffers::Verifiable for UnionInNestedNS {
+  #[inline]
+  fn run_verifier(
+    v: &mut flatbuffers::Verifier, pos: usize
+  ) -> Result<(), flatbuffers::InvalidFlatbuffer> {
+    use self::flatbuffers::Verifiable;
+    u8::run_verifier(v, pos)
+  }
+}
+
+impl flatbuffers::SimpleToVerifyInSlice for UnionInNestedNS {}
+pub struct UnionInNestedNSUnionTableOffset {}
+
+#[allow(clippy::upper_case_acronyms)]
+#[non_exhaustive]
+#[derive(Debug, Clone, PartialEq)]
+pub enum UnionInNestedNST {
+  NONE,
+  TableInNestedNS(Box<TableInNestedNST>),
+}
+impl Default for UnionInNestedNST {
+  fn default() -> Self {
+    Self::NONE
+  }
+}
+impl UnionInNestedNST {
+  pub fn union_in_nested_ns_type(&self) -> UnionInNestedNS {
+    match self {
+      Self::NONE => UnionInNestedNS::NONE,
+      Self::TableInNestedNS(_) => UnionInNestedNS::TableInNestedNS,
+    }
+  }
+  pub fn pack(&self, fbb: &mut flatbuffers::FlatBufferBuilder) -> Option<flatbuffers::WIPOffset<flatbuffers::UnionWIPOffset>> {
+    match self {
+      Self::NONE => None,
+      Self::TableInNestedNS(v) => Some(v.pack(fbb).as_union_value()),
+    }
+  }
+  /// If the union variant matches, return the owned TableInNestedNST, setting the union to NONE.
+  pub fn take_table_in_nested_ns(&mut self) -> Option<Box<TableInNestedNST>> {
+    if let Self::TableInNestedNS(_) = self {
+      let v = std::mem::replace(self, Self::NONE);
+      if let Self::TableInNestedNS(w) = v {
+        Some(w)
+      } else {
+        unreachable!()
+      }
+    } else {
+      None
+    }
+  }
+  /// If the union variant matches, return a reference to the TableInNestedNST.
+  pub fn as_table_in_nested_ns(&self) -> Option<&TableInNestedNST> {
+    if let Self::TableInNestedNS(v) = self { Some(v.as_ref()) } else { None }
+  }
+  /// If the union variant matches, return a mutable reference to the TableInNestedNST.
+  pub fn as_table_in_nested_ns_mut(&mut self) -> Option<&mut TableInNestedNST> {
+    if let Self::TableInNestedNS(v) = self { Some(v.as_mut()) } else { None }
+  }
+}