Add Windows static CRT support and CI test

.github/workflows/rust.yml

@@ -37,6 +37,11 @@ jobs:
       run: cargo build
     - name: Run tests
       run: cargo test
+    - name: Run tests with static CRT
+      if: matrix.config.os == 'windows-latest'
+      env:
+        RUSTFLAGS: -C target-feature=+crt-static
+      run: cargo test
     - name: Build with system-installed HiGHS
       if: matrix.config.os != 'windows-latest'
       run: |

build.rs

@@ -1,6 +1,13 @@
 use std::env;
 use std::path::{Path, PathBuf};
 
+fn target_has_feature(feature: &str) -> bool {
+    env::var("CARGO_CFG_TARGET_FEATURE")
+        .unwrap_or_default()
+        .split(',')
+        .any(|enabled_feature| enabled_feature == feature)
+}
+
 /// Used to exclude autogenerated files in the output dir from `cargo:rerun-if-changed` directives.
 #[derive(Debug)]
 pub struct CustomCargoCallbacks {
@@ -86,6 +93,7 @@ fn build() -> bool {
     let target = env::var("TARGET").unwrap();
     let emscripten = target.contains("emscripten");
     let mut dst = Config::new("HiGHS");
+    let crt_static = target_has_feature("crt-static");
 
     if cfg!(feature = "ninja") {
         dst.generator("Ninja");
@@ -109,7 +117,14 @@ fn build() -> bool {
     let dst = dst
         .define("FAST_BUILD", "ON")
         .define("BUILD_SHARED_LIBS", "OFF")
-        .define("CMAKE_MSVC_RUNTIME_LIBRARY", "MultiThreadedDLL")
+        .define(
+            "CMAKE_MSVC_RUNTIME_LIBRARY",
+            if crt_static {
+                "MultiThreaded"
+            } else {
+                "MultiThreadedDLL"
+            },
+        )
         .define("CMAKE_INTERPROCEDURAL_OPTIMIZATION", "FALSE")
         .define("ZLIB", if cfg!(feature = "libz") { "ON" } else { "OFF" })
         .build();
@@ -164,6 +179,10 @@ fn discover() -> bool {
 }
 
 fn main() {
+    println!("cargo:rerun-if-env-changed=CARGO_CFG_TARGET_FEATURE");
+
+    let crt_static = target_has_feature("crt-static");
+
     if cfg!(all(
         any(
             feature = "highs_release",
@@ -173,11 +192,20 @@ fn main() {
         not(feature = "build")
     )) {
         panic!(
-            "You have enabled features that control how HiGHS is built, but have not enabled the 'build' feature.\n\
+            "You have enabled features that control how HiGHS is built, but have not enabled the 'build' feature.
+\
                Thus, your features will never have any effect. Please enable the 'build' feature on highs-sys if you want to build HiGHS or disable the 'libz', 'ninja' and 'highs_release' features."
         );
     }
 
+    if cfg!(feature = "discover") && crt_static {
+        panic!(
+            "You have enabled Rust's 'crt-static' target feature, but also enabled the 'discover' feature.
+\
+               Discovering a system-installed HiGHS bypasses the bundled build, so highs-sys cannot ensure that HiGHS uses the same MSVC runtime. Please disable 'discover' when using '-C target-feature=+crt-static'."
+        );
+    }
+
     if !discover() && !build() {
         panic!("Could neither discover nor build HiGHS");
     }