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>

MODULE.bazel

@@ -43,6 +43,10 @@ bazel_dep(
     name = "rules_nodejs",
     version = "6.3.3",
 )
+bazel_dep(
+    name = "rules_shell",
+    version = "0.3.0",
+)
 bazel_dep(
     name = "rules_swift",
     version = "1.18.0",

rust/flatbuffers/Cargo.toml

@@ -17,7 +17,7 @@ std = []
 serialize = ["serde"]
 
 [dependencies]
-bitflags = "1.2.1"
+bitflags = "2.8.0"
 serde = { version = "1.0", optional = true }
 
 [build-dependencies]

rust/reflection/Cargo.toml

@@ -5,8 +5,6 @@ edition = "2021"
 
 [dependencies]
 flatbuffers = { path = "../flatbuffers"}
-escape_string = "0.1.2"
+num-traits = "0.2.19"
-stdint = "0.2.0"
-num = "0.4.1"
 anyhow = "1.0.75"
 thiserror = "1.0"

rust/reflection/src/lib.rs

@@ -29,11 +29,9 @@ use flatbuffers::{
 use reflection_generated::reflection::{BaseType, Field, Object, Schema};
 
 use core::mem::size_of;
-use escape_string::escape;
+use num_traits::float::Float;
-use num::traits::float::Float;
+use num_traits::int::PrimInt;
-use num::traits::int::PrimInt;
+use num_traits::FromPrimitive;
-use num::traits::FromPrimitive;
-use stdint::uintmax_t;
 use thiserror::Error;
 
 #[derive(Error, Debug, PartialEq)]
@@ -541,7 +539,9 @@ pub unsafe fn set_string(
 
     if delta != 0 {
         // Rounds the delta up to the nearest multiple of the maximum int size to keep the types after the insersion point aligned.
-        let mask = (size_of::<uintmax_t>() - 1) as isize;
+        // stdint crate defines intmax_t as an alias for c_long; use it directly to avoid extra
+        // dependency.
+        let mask = (size_of::<core::ffi::c_long>() - 1) as isize;
         let offset = (delta + mask) & !mask;
         let mut visited_vec = vec![false; buf.len()];
 
@@ -715,7 +715,8 @@ unsafe fn get_any_value_string(
                     }
                     let mut field_value = get_any_field_string(&table, &field, schema);
                     if field.type_().base_type() == BaseType::String {
-                        field_value = escape(field_value.as_str()).to_string();
+                        // Escape the string
+                        field_value = format!("{:?}", field_value.as_str());
                     }
                     s += field.name();
                     s += ": ";

rust/reflection/src/safe_buffer.rs

@@ -25,9 +25,9 @@ use crate::{
     FlatbufferResult, ForwardsUOffset,
 };
 use flatbuffers::{Follow, Table, Vector, VerifierOptions};
-use num::traits::float::Float;
+use num_traits::float::Float;
-use num::traits::int::PrimInt;
+use num_traits::int::PrimInt;
-use num::traits::FromPrimitive;
+use num_traits::FromPrimitive;
 use std::collections::HashMap;
 
 #[derive(Debug)]

src/idl_gen_rust.cpp

@@ -727,7 +727,7 @@ class RustGenerator : public BaseGenerator {
       code_ += "mod bitflags_{{ENUM_NAMESPACE}} {";
       code_ += "  flatbuffers::bitflags::bitflags! {";
       GenComment(enum_def.doc_comment, "    ");
-      code_ += "    #[derive(Default)]";
+      code_ += "    #[derive(Default, Debug, Clone, Copy, PartialEq)]";
       code_ += "    {{ACCESS_TYPE}} struct {{ENUM_TY}}: {{BASE_TYPE}} {";
       ForAllEnumValues1(enum_def, [&](const EnumVal &ev) {
         this->GenComment(ev.doc_comment, "    ");
@@ -843,20 +843,7 @@ class RustGenerator : public BaseGenerator {
     code_ +=
         "    let b = flatbuffers::read_scalar_at::<{{BASE_TYPE}}>(buf, loc);";
     if (IsBitFlagsEnum(enum_def)) {
-      // Safety:
+      code_ += "    Self::from_bits_retain(b)";
-      // 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
-      code_ += "    // Safety:";
-      code_ +=
-          "    // This is safe because we know bitflags is implemented with a "
-          "repr transparent uint of the correct size.";
-      code_ +=
-          "    // from_bits_unchecked will be replaced by an equivalent but "
-          "safe from_bits_retain in bitflags 2.0";
-      code_ += "    // https://github.com/bitflags/bitflags/issues/262";
-      code_ += "    Self::from_bits_unchecked(b)";
     } else {
       code_ += "    Self(b)";
     }
@@ -884,20 +871,7 @@ class RustGenerator : public BaseGenerator {
     code_ += "  fn from_little_endian(v: {{BASE_TYPE}}) -> Self {";
     code_ += "    let b = {{BASE_TYPE}}::from_le(v);";
     if (IsBitFlagsEnum(enum_def)) {
-      // Safety:
+      code_ += "    Self::from_bits_retain(b)";
-      // 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
-      code_ += "    // Safety:";
-      code_ +=
-          "    // This is safe because we know bitflags is implemented with a "
-          "repr transparent uint of the correct size.";
-      code_ +=
-          "    // from_bits_unchecked will be replaced by an equivalent but "
-          "safe from_bits_retain in bitflags 2.0";
-      code_ += "    // https://github.com/bitflags/bitflags/issues/262";
-      code_ += "    unsafe { Self::from_bits_unchecked(b) }";
     } else {
       code_ += "    Self(b)";
     }

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:
+    Self::from_bits_retain(b)
-    // 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)
   }
 }
 
@@ -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:
+    Self::from_bits_retain(b)
-    // 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) }
   }
 }
 

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:
+    Self::from_bits_retain(b)
-    // 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)
   }
 }
 
@@ -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:
+    Self::from_bits_retain(b)
-    // 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) }
   }
 }
 

tests/monster_test_serialize/my_game/example/color_generated.rs

@@ -15,7 +15,7 @@ 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
@@ -42,11 +42,7 @@ 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:
+    Self::from_bits_retain(b)
-    // 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)
   }
 }
 
@@ -68,11 +64,7 @@ impl flatbuffers::EndianScalar for Color {
   #[allow(clippy::wrong_self_convention)]
   fn from_little_endian(v: u8) -> Self {
     let b = u8::from_le(v);
-    // Safety:
+    Self::from_bits_retain(b)
-    // 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) }
   }
 }
 

tests/monster_test_serialize/my_game/example/long_enum_generated.rs

@@ -14,7 +14,7 @@ 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;
@@ -38,11 +38,7 @@ 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:
+    Self::from_bits_retain(b)
-    // 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)
   }
 }
 
@@ -64,11 +60,7 @@ impl flatbuffers::EndianScalar for LongEnum {
   #[allow(clippy::wrong_self_convention)]
   fn from_little_endian(v: u64) -> Self {
     let b = u64::from_le(v);
-    // Safety:
+    Self::from_bits_retain(b)
-    // 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) }
   }
 }
 

tests/rust_usage_test/tests/integration_test.rs

@@ -1767,19 +1767,19 @@ mod write_and_read_examples {
         assert_eq!(
             format!("{:.5?}", &m),
             "Monster { pos: Some(Vec3 { x: 1.00000, y: 2.00000, z: 3.00000, \
-            test1: 3.00000, test2: Green, test3: Test { a: 5, b: 6 } }), \
+            test1: 3.00000, test2: Color(Green), test3: Test { a: 5, b: 6 } \
-            mana: 150, hp: 80, name: \"MyMonster\", \
+            }), mana: 150, hp: 80, name: \"MyMonster\", inventory: Some([0, 1, \
-            inventory: Some([0, 1, 2, 3, 4]), color: Blue, test_type: Monster, \
+            2, 3, 4]), color: Color(Blue), test_type: Monster, test: Monster { \
-            test: Monster { pos: None, mana: 150, hp: 100, name: \"Fred\", \
+            pos: None, mana: 150, hp: 100, name: \"Fred\", inventory: None, \
-            inventory: None, color: Blue, test_type: NONE, test: None, \
+            color: Color(Blue), test_type: NONE, test: None, test4: None, \
-            test4: None, testarrayofstring: None, testarrayoftables: None, \
+            testarrayofstring: None, testarrayoftables: None, enemy: None, \
-            enemy: None, testnestedflatbuffer: None, testempty: None, \
+            testnestedflatbuffer: None, testempty: None, testbool: false, \
-            testbool: false, testhashs32_fnv1: 0, testhashu32_fnv1: 0, \
+            testhashs32_fnv1: 0, testhashu32_fnv1: 0, testhashs64_fnv1: 0, \
-            testhashs64_fnv1: 0, testhashu64_fnv1: 0, testhashs32_fnv1a: 0, \
+            testhashu64_fnv1: 0, testhashs32_fnv1a: 0, testhashu32_fnv1a: 0, \
-            testhashu32_fnv1a: 0, testhashs64_fnv1a: 0, testhashu64_fnv1a: 0, \
+            testhashs64_fnv1a: 0, testhashu64_fnv1a: 0, testarrayofbools: \
-            testarrayofbools: None, testf: 3.14159, testf2: 3.00000, testf3: 0.00000, \
+            None, testf: 3.14159, testf2: 3.00000, testf3: 0.00000, \
-            testarrayofstring2: None, testarrayofsortedstruct: None, flex: None, \
+            testarrayofstring2: None, testarrayofsortedstruct: None, flex: \
-            test5: None, vector_of_longs: None, vector_of_doubles: None, \
+            None, test5: None, vector_of_longs: None, vector_of_doubles: None, \
             parent_namespace_test: None, vector_of_referrables: None, \
             single_weak_reference: 0, vector_of_weak_references: None, \
             vector_of_strong_referrables: None, co_owning_reference: 0, \
@@ -1787,22 +1787,22 @@ mod write_and_read_examples {
             vector_of_non_owning_references: None, any_unique_type: NONE, \
             any_unique: None, any_ambiguous_type: NONE, any_ambiguous: None, \
             vector_of_enums: None, signed_enum: None, \
-            testrequirednestedflatbuffer: None, scalar_key_sorted_tables: None, \
+            testrequirednestedflatbuffer: None, scalar_key_sorted_tables: \
-            native_inline: None, long_enum_non_enum_default: (empty), \
+            None, native_inline: None, long_enum_non_enum_default: \
-            long_enum_normal_default: LongOne, nan_default: NaN, inf_default: \
+            LongEnum(0x0), long_enum_normal_default: LongEnum(LongOne), \
-            inf, positive_inf_default: inf, infinity_default: inf, \
+            nan_default: NaN, inf_default: inf, positive_inf_default: inf, \
-            positive_infinity_default: inf, negative_inf_default: -inf, \
+            infinity_default: inf, positive_infinity_default: inf, \
-            negative_infinity_default: -inf, double_inf_default: inf }, \
+            negative_inf_default: -inf, negative_infinity_default: -inf, \
-            test4: Some([Test { a: 10, b: 20 }, Test { a: 30, b: 40 }]), \
+            double_inf_default: inf }, test4: Some([Test { a: 10, b: 20 }, \
-            testarrayofstring: Some([\"test1\", \"test2\"]), \
+            Test { a: 30, b: 40 }]), testarrayofstring: Some([\"test1\", \
-            testarrayoftables: None, enemy: None, testnestedflatbuffer: None, \
+            \"test2\"]), testarrayoftables: None, enemy: None, \
-            testempty: None, testbool: false, testhashs32_fnv1: 0, \
+            testnestedflatbuffer: None, testempty: None, testbool: false, \
-            testhashu32_fnv1: 0, testhashs64_fnv1: 0, testhashu64_fnv1: 0, \
+            testhashs32_fnv1: 0, testhashu32_fnv1: 0, testhashs64_fnv1: 0, \
-            testhashs32_fnv1a: 0, testhashu32_fnv1a: 0, testhashs64_fnv1a: 0, \
+            testhashu64_fnv1: 0, testhashs32_fnv1a: 0, testhashu32_fnv1a: 0, \
-            testhashu64_fnv1a: 0, testarrayofbools: None, testf: 3.14159, \
+            testhashs64_fnv1a: 0, testhashu64_fnv1a: 0, testarrayofbools: \
-            testf2: 3.00000, testf3: 0.00000, testarrayofstring2: None, \
+            None, testf: 3.14159, testf2: 3.00000, testf3: 0.00000, \
-            testarrayofsortedstruct: None, flex: None, test5: None, \
+            testarrayofstring2: None, testarrayofsortedstruct: None, flex: \
-            vector_of_longs: None, vector_of_doubles: None, \
+            None, test5: None, vector_of_longs: None, vector_of_doubles: None, \
             parent_namespace_test: None, vector_of_referrables: None, \
             single_weak_reference: 0, vector_of_weak_references: None, \
             vector_of_strong_referrables: None, co_owning_reference: 0, \
@@ -1810,12 +1810,13 @@ mod write_and_read_examples {
             vector_of_non_owning_references: None, any_unique_type: NONE, \
             any_unique: None, any_ambiguous_type: NONE, any_ambiguous: None, \
             vector_of_enums: None, signed_enum: None, \
-            testrequirednestedflatbuffer: None, scalar_key_sorted_tables: None, \
+            testrequirednestedflatbuffer: None, scalar_key_sorted_tables: \
-            native_inline: None, long_enum_non_enum_default: (empty), \
+            None, native_inline: None, long_enum_non_enum_default: \
-            long_enum_normal_default: LongOne, nan_default: NaN, inf_default: \
+            LongEnum(0x0), long_enum_normal_default: LongEnum(LongOne), \
-            inf, positive_inf_default: inf, infinity_default: inf, \
+            nan_default: NaN, inf_default: inf, positive_inf_default: inf, \
-            positive_infinity_default: inf, negative_inf_default: -inf, \
+            infinity_default: inf, positive_infinity_default: inf, \
-            negative_infinity_default: -inf, double_inf_default: inf }"
+            negative_inf_default: -inf, negative_infinity_default: -inf, \
+            double_inf_default: inf }"
         );
     }
 

tests/swift/tests/Package.swift

@@ -26,6 +26,10 @@ let package = Package(
   dependencies: [
     .package(path: "../../.."),
     .package(url: "https://github.com/grpc/grpc-swift.git", from: "1.4.1"),
+    // Prevent the build system from pulling 2.29.1 to prevent Swift 5.8 build breaks.
+    // The patch update introduced code that uses "switch expression syntax" that wasn't valid until Swift 5.9 [1].
+    // [1] https://github.com/swiftlang/swift-evolution/blob/main/proposals/0380-if-switch-expressions.md
+    .package(url: "https://github.com/apple/swift-nio-ssl.git", exact: "2.29.0"),
   ],
   targets: [
     .executableTarget(

ts/BUILD.bazel

@@ -1,6 +1,7 @@
 load("@aspect_rules_js//npm:defs.bzl", "npm_package")
 load("@aspect_rules_ts//ts:defs.bzl", "ts_project")
 load("@flatbuffers_npm//:defs.bzl", "npm_link_all_packages")
+load("@rules_shell//shell:sh_binary.bzl", "sh_binary")
 
 filegroup(
     name = "distribution",