Don't depend on or-tools for docs.rs

Cargo.toml

@@ -10,6 +10,10 @@ keywords = ["constraint", "programming", "CP"]
 categories = ["api-bindings", "mathematics", "science"]
 readme = "README.md"
 
+[features]
+# the doc feature will not build C++ wrappers (not needed by the doc)
+doc = []
+
 [dependencies]
 prost = "0.8"
 bytes = "1.1.0"
@@ -18,3 +22,7 @@ libc = "0.2.101"
 [build-dependencies]
 prost-build = { version = "0.8" }
 cc = "1.0"
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]
+features = ["doc"]

build.rs

@@ -7,16 +7,18 @@ fn main() {
     )
     .unwrap();
 
-    let ortools_prefix = std::env::var("ORTOOLS_PREFIX")
-        .ok()
-        .unwrap_or("/opt/ortools".into());
-    cc::Build::new()
-        .cpp(true)
-        .flag("-std=c++17")
-        .file("src/cp_sat_wrapper.cpp")
-        .include(&[&ortools_prefix, "/include"].concat())
-        .compile("cp_sat_wrapper.a");
+    if !std::env::var("CARGO_FEATURE_DOC").is_ok() {
+        let ortools_prefix = std::env::var("ORTOOLS_PREFIX")
+            .ok()
+            .unwrap_or("/opt/ortools".into());
+        cc::Build::new()
+            .cpp(true)
+            .flag("-std=c++17")
+            .file("src/cp_sat_wrapper.cpp")
+            .include(&[&ortools_prefix, "/include"].concat())
+            .compile("cp_sat_wrapper.a");
 
-    println!("cargo:rustc-link-lib=dylib=ortools");
-    println!("cargo:rustc-link-search=native={}/lib", ortools_prefix);
+        println!("cargo:rustc-link-lib=dylib=ortools");
+        println!("cargo:rustc-link-search=native={}/lib", ortools_prefix);
+    }
 }