Fix Android build

llama-cpp-2/Cargo.toml

@@ -18,14 +18,16 @@ tracing = { workspace = true }
 encoding_rs = { workspace = true }
 
 [features]
-default = ["openmp"]
+default = ["openmp", "android-shared-stdcxx"]
 cuda = ["llama-cpp-sys-2/cuda"]
 metal = ["llama-cpp-sys-2/metal"]
 dynamic-link = ["llama-cpp-sys-2/dynamic-link"]
 vulkan = ["llama-cpp-sys-2/vulkan"]
 native = ["llama-cpp-sys-2/native"]
 openmp = ["llama-cpp-sys-2/openmp"]
 sampler = []
+# Only has an impact on Android.
+android-shared-stdcxx = ["llama-cpp-sys-2/shared-stdcxx"]
 
 
 [target.'cfg(all(target_os = "macos", any(target_arch = "aarch64", target_arch = "arm64")))'.dependencies]

llama-cpp-2/src/model.rs

@@ -1,5 +1,5 @@
 //! A safe wrapper around `llama_model`.
-use std::ffi::CString;
+use std::ffi::{c_char, CString};
 use std::num::NonZeroU16;
 use std::os::raw::c_int;
 use std::path::Path;
@@ -565,7 +565,7 @@ impl LlamaModel {
                 chat.as_ptr(),
                 chat.len(),
                 add_ass,
-                buff.as_mut_ptr().cast::<i8>(),
+                buff.as_mut_ptr().cast::<c_char>(),
                 buff.len().try_into().expect("Buffer size exceeds i32::MAX"),
             )
         };
@@ -579,7 +579,7 @@ impl LlamaModel {
                     chat.as_ptr(),
                     chat.len(),
                     add_ass,
-                    buff.as_mut_ptr().cast::<i8>(),
+                    buff.as_mut_ptr().cast::<c_char>(),
                     buff.len().try_into().expect("Buffer size exceeds i32::MAX"),
                 )
             };

llama-cpp-2/src/sampling.rs

@@ -1,7 +1,7 @@
 //! Safe wrapper around `llama_sampler`.
 
 use std::borrow::Borrow;
-use std::ffi::CString;
+use std::ffi::{c_char, CString};
 use std::fmt::{Debug, Formatter};
 
 use crate::context::LlamaContext;
@@ -20,14 +20,6 @@ impl Debug for LlamaSampler {
     }
 }
 
-// this is needed for the dry sampler to typecheck on android
-// ...because what is normally an i8, is an u8
-#[cfg(target_os = "android")]
-type CChar = u8;
-
-#[cfg(not(target_os = "android"))]
-type CChar = i8;
-
 impl LlamaSampler {
     /// Sample and accept a token from the idx-th output of the last evaluation
     #[must_use]
@@ -266,7 +258,7 @@ impl LlamaSampler {
             .into_iter()
             .map(|s| CString::new(s.as_ref()).expect("A sequence breaker contains null bytes"))
             .collect();
-        let mut seq_breaker_pointers: Vec<*const CChar> =
+        let mut seq_breaker_pointers: Vec<*const c_char> =
             seq_breakers.iter().map(|s| s.as_ptr()).collect();
 
         let sampler = unsafe {

llama-cpp-sys-2/Cargo.toml

@@ -71,3 +71,5 @@ dynamic-link = []
 vulkan = []
 native = []
 openmp = []
+# Only has an impact on Android.
+shared-stdcxx = []

llama-cpp-sys-2/build.rs

@@ -229,22 +229,44 @@ fn main() {
         config.static_crt(static_crt);
     }
 
-    if target.contains("android") && target.contains("aarch64") {
+    if target.contains("android") {
         // build flags for android taken from this doc
         // https://github.com/ggerganov/llama.cpp/blob/master/docs/android.md
         let android_ndk = env::var("ANDROID_NDK")
             .expect("Please install Android NDK and ensure that ANDROID_NDK env variable is set");
+
+        println!("cargo::rerun-if-env-changed=ANDROID_NDK");
+
         config.define(
             "CMAKE_TOOLCHAIN_FILE",
             format!("{android_ndk}/build/cmake/android.toolchain.cmake"),
         );
-        config.define("ANDROID_ABI", "arm64-v8a");
-        config.define("ANDROID_PLATFORM", "android-28");
-        config.define("CMAKE_SYSTEM_PROCESSOR", "arm64");
-        config.define("CMAKE_C_FLAGS", "-march=armv8.7a");
-        config.define("CMAKE_CXX_FLAGS", "-march=armv8.7a");
-        config.define("GGML_OPENMP", "OFF");
+        if env::var("ANDROID_PLATFORM").is_ok() {
+            println!("cargo::rerun-if-env-changed=ANDROID_PLATFORM");
+        } else {
+            config.define("ANDROID_PLATFORM", "android-28");
+        }
+        if target.contains("aarch64") {
+            config.cflag("-march=armv8.7a");
+            config.cxxflag("-march=armv8.7a");
+        } else if target.contains("armv7") {
+            config.cflag("-march=armv8.7a");
+            config.cxxflag("-march=armv8.7a");
+        } else if target.contains("x86_64") {
+            config.cflag("-march=x86-64");
+            config.cxxflag("-march=x86-64");
+        } else if target.contains("i686") {
+            config.cflag("-march=i686");
+            config.cxxflag("-march=i686");
+        } else {
+            // Rather than guessing just fail.
+            panic!("Unsupported Android target {target}");
+        }
         config.define("GGML_LLAMAFILE", "OFF");
+        if cfg!(feature = "shared-stdcxx") {
+            println!("cargo:rustc-link-lib=dylib=stdc++");
+            println!("cargo:rustc-link-lib=c++_shared");
+        }
     }
 
     if cfg!(feature = "vulkan") {
@@ -266,8 +288,13 @@ fn main() {
         config.define("GGML_CUDA", "ON");
     }
 
-    if cfg!(feature = "openmp") {
+    // Android doesn't have OpenMP support AFAICT and openmp is a default feature. Do this here
+    // rather than modifying the defaults in Cargo.toml just in case someone enables the OpenMP feature
+    // and tries to build for Android anyway.
+    if cfg!(feature = "openmp") && !target.contains("android") {
         config.define("GGML_OPENMP", "ON");
+    } else {
+        config.define("GGML_OPENMP", "OFF");
     }
 
     // General