Rust reflection: simplify dependencies, fix Android build compatibility (#8512)

* flatbuffers Rust reflection: replace num with num-traits

num crate is a wrapper over num-traits and a few other crates, that
reexports the APIs from all of them. We only need num-traits.

Signed-off-by: Marcin Radomski <dextero@google.com>

* Rust reflection: drop dependency on stdint crate

We only use it to get intmax_t for deriving alignment, which is an alias
for `core::ffi::c_long` [1]. We can use that directly instead.

[1] https://docs.rs/stdint/1.0.0/stdint/type.intmax_t.html

Signed-off-by: Marcin Radomski <dextero@google.com>

* Rust reflection: drop dependency on escape_string crate

It's used to format a string used for debugging only, so we might as
well use the builtin Debug representation of a string.

Signed-off-by: Marcin Radomski <dextero@google.com>

* Rust codegen: add derives on generated bitflags

Otherwise it limits the use of structs generated for reflection.fbs
in Rust reflection API.

Signed-off-by: Marcin Radomski <dextero@google.com>

* Rust flatbuffers: update bitflags dependency to 2.8

Signed-off-by: Marcin Radomski <dextero@google.com>

* Rust codegen: use bitflags v2 API for converting from bits

from_bits_unchecked was replaced with safe from_bits_retain.

Signed-off-by: Marcin Radomski <dextero@google.com>

* Regenerate Rust code after idl change

Signed-off-by: Marcin Radomski <dextero@google.com>

* Regenerate reflection_generated.rs

With flatc --rust ../../../reflection/reflection.fbs

Signed-off-by: Marcin Radomski <dextero@google.com>

* ts/BUILD.bazel: add missing import

Found by Buildifire presubmit:

  Function "sh_binary" is not global anymore and needs to be loaded from
  "@rules_shell//shell:sh_binary.bzl".

Signed-off-by: Marcin Radomski <dextero@google.com>

* Update expected value in generated_code_debug_prints_correctly test

In bitflags v2, the debug string representation of enum values is
different than it was in v1:
  Blue -> Color(Blue)
  (empty) -> LongEnum(0x0)

This change adjusts the expected test value.

Signed-off-by: Marcin Radomski <dextero@google.com>

* Fix tests build on Swift 5.8

grpc-swift 1.4.1 depends on swift-nio-ssl 2.14.0+ [1]. swift-nio-ssl 2.29.1
published on 2025-01-30, introduced some code [2] that uses a "switch
expression syntax" supported since Swift 5.9 [3]. Attempts to compile it with
Swift 5.8 cause build errors.

swift-nio-ssl project doesn't seem to support Swift 5.8. A commit from
2024-10-29 removes a "deprecated reference to a Swift 5.8 pipeline" [4].

swift-nio-ssl 2.29.0 is the last version that can be compiled with Swift
5.8. This commit pins it to that exact version.

[1] 66e27d7e84/Package.swift (L33)
[2] 3cb4d5ad12 (diff-bc1db1321ff689c2819245dcce1a3080554f0fc13f81b8d326c97e7d42717c8fR54)
[3] https://github.com/swiftlang/swift-evolution/blob/main/proposals/0380-if-switch-expressions.md
[4] 8a6b89d9a4

---------

Signed-off-by: Marcin Radomski <dextero@google.com>
Co-authored-by: Marcin Radomski <dextero@google.com>

tests/monster_test/my_game/example/color_generated.rs

@@ -13,7 +13,7 @@ use super::*;
 mod bitflags_color {
   flatbuffers::bitflags::bitflags! {
     /// Composite components of Monster color.
-    #[derive(Default)]
+    #[derive(Default, Debug, Clone, Copy, PartialEq)]
     pub struct Color: u8 {
       const Red = 1;
       /// \brief color Green
@@ -31,11 +31,7 @@ impl<'a> flatbuffers::Follow<'a> for Color {
   #[inline]
   unsafe fn follow(buf: &'a [u8], loc: usize) -> Self::Inner {
     let b = flatbuffers::read_scalar_at::<u8>(buf, loc);
-    // Safety:
-    // This is safe because we know bitflags is implemented with a repr transparent uint of the correct size.
-    // from_bits_unchecked will be replaced by an equivalent but safe from_bits_retain in bitflags 2.0
-    // https://github.com/bitflags/bitflags/issues/262
-    Self::from_bits_unchecked(b)
+    Self::from_bits_retain(b)
   }
 }
 
@@ -57,11 +53,7 @@ impl flatbuffers::EndianScalar for Color {
   #[allow(clippy::wrong_self_convention)]
   fn from_little_endian(v: u8) -> Self {
     let b = u8::from_le(v);
-    // Safety:
-    // This is safe because we know bitflags is implemented with a repr transparent uint of the correct size.
-    // from_bits_unchecked will be replaced by an equivalent but safe from_bits_retain in bitflags 2.0
-    // https://github.com/bitflags/bitflags/issues/262
-    unsafe { Self::from_bits_unchecked(b) }
+    Self::from_bits_retain(b)
   }
 }
 

tests/monster_test/my_game/example/long_enum_generated.rs

@@ -12,7 +12,7 @@ use super::*;
 #[allow(non_upper_case_globals)]
 mod bitflags_long_enum {
   flatbuffers::bitflags::bitflags! {
-    #[derive(Default)]
+    #[derive(Default, Debug, Clone, Copy, PartialEq)]
     pub struct LongEnum: u64 {
       const LongOne = 2;
       const LongTwo = 4;
@@ -27,11 +27,7 @@ impl<'a> flatbuffers::Follow<'a> for LongEnum {
   #[inline]
   unsafe fn follow(buf: &'a [u8], loc: usize) -> Self::Inner {
     let b = flatbuffers::read_scalar_at::<u64>(buf, loc);
-    // Safety:
-    // This is safe because we know bitflags is implemented with a repr transparent uint of the correct size.
-    // from_bits_unchecked will be replaced by an equivalent but safe from_bits_retain in bitflags 2.0
-    // https://github.com/bitflags/bitflags/issues/262
-    Self::from_bits_unchecked(b)
+    Self::from_bits_retain(b)
   }
 }
 
@@ -53,11 +49,7 @@ impl flatbuffers::EndianScalar for LongEnum {
   #[allow(clippy::wrong_self_convention)]
   fn from_little_endian(v: u64) -> Self {
     let b = u64::from_le(v);
-    // Safety:
-    // This is safe because we know bitflags is implemented with a repr transparent uint of the correct size.
-    // from_bits_unchecked will be replaced by an equivalent but safe from_bits_retain in bitflags 2.0
-    // https://github.com/bitflags/bitflags/issues/262
-    unsafe { Self::from_bits_unchecked(b) }
+    Self::from_bits_retain(b)
   }
 }