[Rust] Support alloc-only no_std platforms

conan/travis/build.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 set -e
 set -x

conan/travis/install.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 set -e
 set -x

grpc/build_grpc.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 grpc_1_39_0_githash=58602e20a3f3e48f24a4114c757099b25b947f7b
 

grpc/examples/generate.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 #
 # Copyright 2021 Google Inc. All rights reserved.
 #

grpc/examples/go/format.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 #
 # Copyright 2021 Google Inc. All rights reserved.
 #

reflection/generate_code.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 #
 # Copyright 2016 Google Inc. All rights reserved.
 #

rust/flatbuffers/Cargo.toml

@@ -14,4 +14,8 @@ rust = "1.51"
 [dependencies]
 smallvec = "1.6.1"
 bitflags = "1.2.1"
-thiserror = "1.0.23"
+thiserror = { version = "1.0.23", optional = true }
+
+[features]
+default = ["std"]
+std = ["thiserror"]

rust/flatbuffers/src/array.rs

@@ -17,9 +17,9 @@
 use crate::follow::Follow;
 use crate::vector::VectorIter;
 use crate::EndianScalar;
-use std::fmt::{Debug, Formatter, Result};
-use std::marker::PhantomData;
-use std::mem::size_of;
+use core::fmt::{Debug, Formatter, Result};
+use core::marker::PhantomData;
+use core::mem::size_of;
 
 #[derive(Copy, Clone)]
 pub struct Array<'a, T: 'a, const N: usize>(&'a [u8], PhantomData<T>);

rust/flatbuffers/src/builder.rs

@@ -16,11 +16,12 @@
 
 extern crate smallvec;
 
-use std::cmp::max;
-use std::iter::{DoubleEndedIterator, ExactSizeIterator};
-use std::marker::PhantomData;
-use std::ptr::write_bytes;
-use std::slice::from_raw_parts;
+use alloc::{vec, vec::Vec};
+use core::cmp::max;
+use core::iter::{DoubleEndedIterator, ExactSizeIterator};
+use core::marker::PhantomData;
+use core::ptr::write_bytes;
+use core::slice::from_raw_parts;
 
 use crate::endian_scalar::{emplace_scalar, read_scalar_at};
 use crate::primitives::*;

rust/flatbuffers/src/endian_scalar.rs

@@ -15,7 +15,7 @@
  */
 #![allow(clippy::wrong_self_convention)]
 
-use std::mem::size_of;
+use core::mem::size_of;
 
 /// Trait for values that must be stored in little-endian byte order, but
 /// might be represented in memory as big-endian. Every type that implements

rust/flatbuffers/src/follow.rs

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-use std::marker::PhantomData;
+use core::marker::PhantomData;
 
 /// Follow is a trait that allows us to access FlatBuffers in a declarative,
 /// type safe, and fast way. They compile down to almost no code (after

rust/flatbuffers/src/lib.rs

@@ -28,6 +28,14 @@
 //! At this time, to generate Rust code, you will need the latest `master` version of `flatc`, available from here: <https://github.com/google/flatbuffers>
 //! (On OSX, you can install FlatBuffers from `HEAD` with the Homebrew package manager.)
 
+#![no_std]
+
+// Needed for thiserror
+#[cfg(feature = "std")]
+extern crate std;
+
+extern crate alloc;
+
 mod array;
 mod builder;
 mod endian_scalar;

rust/flatbuffers/src/primitives.rs

@@ -14,9 +14,9 @@
  * limitations under the License.
  */
 
-use std::marker::PhantomData;
-use std::mem::size_of;
-use std::ops::Deref;
+use core::marker::PhantomData;
+use core::mem::size_of;
+use core::ops::Deref;
 
 use crate::endian_scalar::{emplace_scalar, read_scalar, read_scalar_at};
 use crate::follow::Follow;

rust/flatbuffers/src/push.rs

@@ -14,8 +14,8 @@
  * limitations under the License.
  */
 
-use std::cmp::max;
-use std::mem::{align_of, size_of};
+use core::cmp::max;
+use core::mem::{align_of, size_of};
 
 use crate::endian_scalar::emplace_scalar;
 

rust/flatbuffers/src/vector.rs

@@ -14,12 +14,12 @@
  * limitations under the License.
  */
 
-use std::fmt::{Debug, Formatter, Result};
-use std::iter::{DoubleEndedIterator, ExactSizeIterator, FusedIterator};
-use std::marker::PhantomData;
-use std::mem::size_of;
-use std::slice::from_raw_parts;
-use std::str::from_utf8_unchecked;
+use core::fmt::{Debug, Formatter, Result};
+use core::iter::{DoubleEndedIterator, ExactSizeIterator, FusedIterator};
+use core::marker::PhantomData;
+use core::mem::size_of;
+use core::slice::from_raw_parts;
+use core::str::from_utf8_unchecked;
 
 use crate::endian_scalar::read_scalar_at;
 #[cfg(target_endian = "little")]

rust/flatbuffers/src/verifier.rs

@@ -1,6 +1,9 @@
 use crate::follow::Follow;
 use crate::{ForwardsUOffset, SOffsetT, SkipSizePrefix, UOffsetT, VOffsetT, Vector, SIZE_UOFFSET};
-use std::ops::Range;
+use alloc::vec::Vec;
+use core::ops::Range;
+
+#[cfg(feature = "std")]
 use thiserror::Error;
 
 /// Traces the location of data errors. Not populated for Dos detecting errors.
@@ -23,7 +26,7 @@ pub enum ErrorTraceDetail {
 }
 #[derive(PartialEq, Eq, Default, Debug, Clone)]
 pub struct ErrorTrace(Vec<ErrorTraceDetail>);
-impl std::convert::AsRef<[ErrorTraceDetail]> for ErrorTrace {
+impl core::convert::AsRef<[ErrorTraceDetail]> for ErrorTrace {
     #[inline]
     fn as_ref(&self) -> &[ErrorTraceDetail] {
         &self.0
@@ -32,66 +35,82 @@ impl std::convert::AsRef<[ErrorTraceDetail]> for ErrorTrace {
 
 /// Describes how a flatuffer is invalid and, for data errors, roughly where. No extra tracing
 /// information is given for DoS detecting errors since it will probably be a lot.
-#[derive(Clone, Error, Debug, PartialEq, Eq)]
+#[derive(Clone, Debug, PartialEq, Eq)]
+#[cfg_attr(feature = "std", derive(Error))]
 pub enum InvalidFlatbuffer {
-    #[error("Missing required field `{required}`.\n{error_trace}")]
+    #[cfg_attr(
+        feature = "std",
+        error("Missing required field `{required}`.\n{error_trace}")
+    )]
     MissingRequiredField {
         required: &'static str,
         error_trace: ErrorTrace,
     },
-    #[error(
-        "Union exactly one of union discriminant (`{field_type}`) and value \
+    #[cfg_attr(
+        feature = "std",
+        error(
+            "Union exactly one of union discriminant (`{field_type}`) and value \
              (`{field}`) are present.\n{error_trace}"
+        )
     )]
     InconsistentUnion {
         field: &'static str,
         field_type: &'static str,
         error_trace: ErrorTrace,
     },
-    #[error("Utf8 error for string in {range:?}: {error}\n{error_trace}")]
+    #[cfg_attr(
+        feature = "std",
+        error("Utf8 error for string in {range:?}: {error}\n{error_trace}")
+    )]
     Utf8Error {
-        #[source]
-        error: std::str::Utf8Error,
+        #[cfg_attr(feature = "std", source)]
+        error: core::str::Utf8Error,
         range: Range<usize>,
         error_trace: ErrorTrace,
     },
-    #[error("String in range [{}, {}) is missing its null terminator.\n{error_trace}",
-            range.start, range.end)]
+    #[cfg_attr(feature = "std", error("String in range [{}, {}) is missing its null terminator.\n{error_trace}",
+            range.start, range.end))]
     MissingNullTerminator {
         range: Range<usize>,
         error_trace: ErrorTrace,
     },
-    #[error("Type `{unaligned_type}` at position {position} is unaligned.\n{error_trace}")]
+    #[cfg_attr(
+        feature = "std",
+        error("Type `{unaligned_type}` at position {position} is unaligned.\n{error_trace}")
+    )]
     Unaligned {
         position: usize,
         unaligned_type: &'static str,
         error_trace: ErrorTrace,
     },
-    #[error("Range [{}, {}) is out of bounds.\n{error_trace}", range.start, range.end)]
+    #[cfg_attr(feature = "std", error("Range [{}, {}) is out of bounds.\n{error_trace}", range.start, range.end))]
     RangeOutOfBounds {
         range: Range<usize>,
         error_trace: ErrorTrace,
     },
-    #[error(
-        "Signed offset at position {position} has value {soffset} which points out of bounds.\
+    #[cfg_attr(
+        feature = "std",
+        error(
+            "Signed offset at position {position} has value {soffset} which points out of bounds.\
              \n{error_trace}"
+        )
     )]
     SignedOffsetOutOfBounds {
         soffset: SOffsetT,
         position: usize,
         error_trace: ErrorTrace,
     },
     // Dos detecting errors. These do not get error traces since it will probably be very large.
-    #[error("Too many tables.")]
+    #[cfg_attr(feature = "std", error("Too many tables."))]
     TooManyTables,
-    #[error("Apparent size too large.")]
+    #[cfg_attr(feature = "std", error("Apparent size too large."))]
     ApparentSizeTooLarge,
-    #[error("Nested table depth limit reached.")]
+    #[cfg_attr(feature = "std", error("Nested table depth limit reached."))]
     DepthLimitReached,
 }
 
-impl std::fmt::Display for ErrorTrace {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+impl core::fmt::Display for ErrorTrace {
+    fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
         use ErrorTraceDetail::*;
         for e in self.0.iter() {
             match e {
@@ -125,7 +144,7 @@ impl std::fmt::Display for ErrorTrace {
     }
 }
 
-pub type Result<T> = std::prelude::v1::Result<T, InvalidFlatbuffer>;
+pub type Result<T> = core::prelude::v1::Result<T, InvalidFlatbuffer>;
 
 impl InvalidFlatbuffer {
     fn new_range_oob<T>(start: usize, end: usize) -> Result<T> {
@@ -245,11 +264,11 @@ impl<'opts, 'buf> Verifier<'opts, 'buf> {
     /// `buffer[0]`. TODO(caspern).
     #[inline]
     fn is_aligned<T>(&self, pos: usize) -> Result<()> {
-        if pos % std::mem::align_of::<T>() == 0 {
+        if pos % core::mem::align_of::<T>() == 0 {
             Ok(())
         } else {
             Err(InvalidFlatbuffer::Unaligned {
-                unaligned_type: std::any::type_name::<T>(),
+                unaligned_type: core::any::type_name::<T>(),
                 position: pos,
                 error_trace: Default::default(),
             })
@@ -271,7 +290,7 @@ impl<'opts, 'buf> Verifier<'opts, 'buf> {
     #[inline]
     pub fn in_buffer<T>(&mut self, pos: usize) -> Result<()> {
         self.is_aligned::<T>(pos)?;
-        self.range_in_buffer(pos, std::mem::size_of::<T>())
+        self.range_in_buffer(pos, core::mem::size_of::<T>())
     }
     #[inline]
     fn get_u16(&mut self, pos: usize) -> Result<u16> {
@@ -416,7 +435,7 @@ impl<'ver, 'opts, 'buf> TableVerifier<'ver, 'opts, 'buf> {
     where
         Key: Follow<'buf> + Verifiable,
         UnionVerifier:
-            (std::ops::FnOnce(<Key as Follow<'buf>>::Inner, &mut Verifier, usize) -> Result<()>),
+            (core::ops::FnOnce(<Key as Follow<'buf>>::Inner, &mut Verifier, usize) -> Result<()>),
         // NOTE: <Key as Follow<'buf>>::Inner == Key
     {
         // TODO(caspern): how to trace vtable errors?
@@ -468,14 +487,14 @@ impl<T: Verifiable> Verifiable for ForwardsUOffset<T> {
 }
 
 /// Checks and returns the range containing the flatbuffers vector.
-fn verify_vector_range<T>(v: &mut Verifier, pos: usize) -> Result<std::ops::Range<usize>> {
+fn verify_vector_range<T>(v: &mut Verifier, pos: usize) -> Result<core::ops::Range<usize>> {
     let len = v.get_uoffset(pos)? as usize;
     let start = pos.saturating_add(SIZE_UOFFSET);
     v.is_aligned::<T>(start)?;
-    let size = len.saturating_mul(std::mem::size_of::<T>());
+    let size = len.saturating_mul(core::mem::size_of::<T>());
     let end = start.saturating_add(size);
     v.range_in_buffer(start, size)?;
-    Ok(std::ops::Range { start, end })
+    Ok(core::ops::Range { start, end })
 }
 
 pub trait SimpleToVerifyInSlice {}
@@ -509,7 +528,7 @@ impl<T: Verifiable> Verifiable for Vector<'_, ForwardsUOffset<T>> {
     #[inline]
     fn run_verifier(v: &mut Verifier, pos: usize) -> Result<()> {
         let range = verify_vector_range::<ForwardsUOffset<T>>(v, pos)?;
-        let size = std::mem::size_of::<ForwardsUOffset<T>>();
+        let size = core::mem::size_of::<ForwardsUOffset<T>>();
         for (i, element_pos) in range.step_by(size).enumerate() {
             trace_elem(
                 <ForwardsUOffset<T>>::run_verifier(v, element_pos),
@@ -526,7 +545,7 @@ impl<'a> Verifiable for &'a str {
     fn run_verifier(v: &mut Verifier, pos: usize) -> Result<()> {
         let range = verify_vector_range::<u8>(v, pos)?;
         let has_null_terminator = v.buffer.get(range.end).map(|&b| b == 0).unwrap_or(false);
-        let s = std::str::from_utf8(&v.buffer[range.clone()]);
+        let s = core::str::from_utf8(&v.buffer[range.clone()]);
         if let Err(error) = s {
             return Err(InvalidFlatbuffer::Utf8Error {
                 error,

rust/flatbuffers/src/vtable_writer.rs

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-use std::ptr::write_bytes;
+use core::ptr::write_bytes;
 
 use crate::endian_scalar::emplace_scalar;
 use crate::primitives::*;

samples/csharp_sample.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 #
 # Copyright 2015 Google Inc. All rights reserved.
 #

samples/dart_sample.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 set -euo
 #
 # Copyright 2018 Dan Field. All rights reserved.

samples/go_sample.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 #
 # Copyright 2015 Google Inc. All rights reserved.
 #

samples/java_sample.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 #
 # Copyright 2015 Google Inc. All rights reserved.
 #

samples/javascript_sample.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 #
 # Copyright 2015 Google Inc. All rights reserved.
 #

samples/kotlin_sample.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 #
 # Copyright 2015 Google Inc. All rights reserved.
 #