separated section for gcc or clang-only flags

Author: youknowone

src/lib.rs

@@ -1750,28 +1750,34 @@ impl Build {
                 }
             }
             ToolFamily::Gnu | ToolFamily::Clang => {
-                // arm-linux-androideabi-gcc 4.8 shipped with Android NDK does
-                // not support '-Oz'
-                if opt_level == "z" && cmd.family != ToolFamily::Clang {
-                    cmd.push_opt_unless_duplicate("-Os".into());
-                } else {
-                    cmd.push_opt_unless_duplicate(format!("-O{}", opt_level).into());
-                }
-
-                if cmd.family == ToolFamily::Clang && target.contains("windows") {
-                    // Disambiguate mingw and msvc on Windows. Problem is that
-                    // depending on the origin clang can default to a mismatchig
-                    // run-time.
-                    cmd.push_cc_arg(format!("--target={}", target).into());
-                }
+                match cmd.family {
+                    ToolFamily::Gnu => {
+                        // arm-linux-androideabi-gcc 4.8 shipped with Android NDK does
+                        // not support '-Oz'
+                        if opt_level == "z" {
+                            cmd.push_opt_unless_duplicate("-Os".into());
+                        } else {
+                            cmd.push_opt_unless_duplicate(format!("-O{}", opt_level).into());
+                        }
+                    }
+                    ToolFamily::Clang => {
+                        if target.contains("windows") {
+                            // Disambiguate mingw and msvc on Windows. Problem is that
+                            // depending on the origin clang can default to a mismatchig
+                            // run-time.
+                            cmd.push_cc_arg(format!("--target={}", target).into());
+                        }
 
-                if cmd.family == ToolFamily::Clang && target.contains("android") {
-                    // For compatibility with code that doesn't use pre-defined `__ANDROID__` macro.
-                    // If compiler used via ndk-build or cmake (officially supported build methods)
-                    // this macros is defined.
-                    // See https://android.googlesource.com/platform/ndk/+/refs/heads/ndk-release-r21/build/cmake/android.toolchain.cmake#456
-                    // https://android.googlesource.com/platform/ndk/+/refs/heads/ndk-release-r21/build/core/build-binary.mk#141
-                    cmd.push_opt_unless_duplicate("-DANDROID".into());
+                        if target.contains("android") {
+                            // For compatibility with code that doesn't use pre-defined `__ANDROID__` macro.
+                            // If compiler used via ndk-build or cmake (officially supported build methods)
+                            // this macros is defined.
+                            // See https://android.googlesource.com/platform/ndk/+/refs/heads/ndk-release-r21/build/cmake/android.toolchain.cmake#456
+                            // https://android.googlesource.com/platform/ndk/+/refs/heads/ndk-release-r21/build/core/build-binary.mk#141
+                            cmd.push_opt_unless_duplicate("-DANDROID".into());
+                        }
+                    }
+                    _ => unreachable!("MSVC never reaches here."),
                 }
 
                 if !target.contains("apple-ios")