Constrain -Clto and -Cembed-bitcode flag inheritance to be clang-only (#1379)

Author: jieyouxu

src/flags.rs

@@ -209,17 +209,6 @@ impl<'this> RustcCodegenFlags<'this> {
                     push_if_supported(format!("-mguard={cc_val}").into());
                 }
             }
-            // https://clang.llvm.org/docs/ClangCommandLineReference.html#cmdoption-clang-flto
-            if let Some(value) = self.lto {
-                let cc_val = match value {
-                    "y" | "yes" | "on" | "true" | "fat" => Some("full"),
-                    "thin" => Some("thin"),
-                    _ => None,
-                };
-                if let Some(cc_val) = cc_val {
-                    push_if_supported(format!("-flto={cc_val}").into());
-                }
-            }
             // https://clang.llvm.org/docs/ClangCommandLineReference.html#cmdoption-clang-fPIC
             // https://clang.llvm.org/docs/ClangCommandLineReference.html#cmdoption-clang-fPIE
             // https://clang.llvm.org/docs/ClangCommandLineReference.html#cmdoption-clang-mdynamic-no-pic
@@ -234,11 +223,6 @@ impl<'this> RustcCodegenFlags<'this> {
                     push_if_supported(cc_flag.into());
                 }
             }
-            // https://clang.llvm.org/docs/ClangCommandLineReference.html#cmdoption-clang-fembed-bitcode
-            if let Some(value) = self.embed_bitcode {
-                let cc_val = if value { "all" } else { "off" };
-                push_if_supported(format!("-fembed-bitcode={cc_val}").into());
-            }
             // https://clang.llvm.org/docs/ClangCommandLineReference.html#cmdoption-clang-fno-omit-frame-pointer
             // https://clang.llvm.org/docs/ClangCommandLineReference.html#cmdoption-clang-fomit-frame-pointer
             if let Some(value) = self.force_frame_pointers {
@@ -285,6 +269,24 @@ impl<'this> RustcCodegenFlags<'this> {
                 if let Some(value) = self.profile_use {
                     push_if_supported(format!("-fprofile-use={value}").into());
                 }
+
+                // https://clang.llvm.org/docs/ClangCommandLineReference.html#cmdoption-clang-fembed-bitcode
+                if let Some(value) = self.embed_bitcode {
+                    let cc_val = if value { "all" } else { "off" };
+                    push_if_supported(format!("-fembed-bitcode={cc_val}").into());
+                }
+
+                // https://clang.llvm.org/docs/ClangCommandLineReference.html#cmdoption-clang-flto
+                if let Some(value) = self.lto {
+                    let cc_val = match value {
+                        "y" | "yes" | "on" | "true" | "fat" => Some("full"),
+                        "thin" => Some("thin"),
+                        _ => None,
+                    };
+                    if let Some(cc_val) = cc_val {
+                        push_if_supported(format!("-flto={cc_val}").into());
+                    }
+                }
             }
             ToolFamily::Gnu { .. } => {}
             ToolFamily::Msvc { .. } => {