Rollup merge of rust-lang#86016 - luqmana:infer-linker-flavor, r=petrochenkov

Unify duplicate linker_and_flavor methods in rustc_codegen_{cranelift,ssa}.

The two methods were exactly the same so this removes the cranelift copy. This will help make sure both they don't get out of sync.

Author: JohnTitor

src/toolchain.rs

@@ -2,9 +2,8 @@
 
 use std::path::PathBuf;
 
-use rustc_middle::bug;
+use rustc_codegen_ssa::back::link::linker_and_flavor;
 use rustc_session::Session;
-use rustc_target::spec::LinkerFlavor;
 
 /// Tries to infer the path of a binary for the target toolchain from the linker name.
 pub(crate) fn get_toolchain_binary(sess: &Session, tool: &str) -> PathBuf {
@@ -30,90 +29,3 @@ pub(crate) fn get_toolchain_binary(sess: &Session, tool: &str) -> PathBuf {
 
     linker
 }
-
-// Adapted from https://github.com/rust-lang/rust/blob/5db778affee7c6600c8e7a177c48282dab3f6292/src/librustc_codegen_ssa/back/link.rs#L848-L931
-fn linker_and_flavor(sess: &Session) -> (PathBuf, LinkerFlavor) {
-    fn infer_from(
-        sess: &Session,
-        linker: Option<PathBuf>,
-        flavor: Option<LinkerFlavor>,
-    ) -> Option<(PathBuf, LinkerFlavor)> {
-        match (linker, flavor) {
-            (Some(linker), Some(flavor)) => Some((linker, flavor)),
-            // only the linker flavor is known; use the default linker for the selected flavor
-            (None, Some(flavor)) => Some((
-                PathBuf::from(match flavor {
-                    LinkerFlavor::Em => {
-                        if cfg!(windows) {
-                            "emcc.bat"
-                        } else {
-                            "emcc"
-                        }
-                    }
-                    LinkerFlavor::Gcc => {
-                        if cfg!(any(target_os = "solaris", target_os = "illumos")) {
-                            // On historical Solaris systems, "cc" may have
-                            // been Sun Studio, which is not flag-compatible
-                            // with "gcc".  This history casts a long shadow,
-                            // and many modern illumos distributions today
-                            // ship GCC as "gcc" without also making it
-                            // available as "cc".
-                            "gcc"
-                        } else {
-                            "cc"
-                        }
-                    }
-                    LinkerFlavor::Ld => "ld",
-                    LinkerFlavor::Msvc => "link.exe",
-                    LinkerFlavor::Lld(_) => "lld",
-                    LinkerFlavor::PtxLinker => "rust-ptx-linker",
-                    LinkerFlavor::BpfLinker => "bpf-linker",
-                }),
-                flavor,
-            )),
-            (Some(linker), None) => {
-                let stem = linker.file_stem().and_then(|stem| stem.to_str()).unwrap_or_else(|| {
-                    sess.fatal("couldn't extract file stem from specified linker")
-                });
-
-                let flavor = if stem == "emcc" {
-                    LinkerFlavor::Em
-                } else if stem == "gcc"
-                    || stem.ends_with("-gcc")
-                    || stem == "clang"
-                    || stem.ends_with("-clang")
-                {
-                    LinkerFlavor::Gcc
-                } else if stem == "ld" || stem == "ld.lld" || stem.ends_with("-ld") {
-                    LinkerFlavor::Ld
-                } else if stem == "link" || stem == "lld-link" {
-                    LinkerFlavor::Msvc
-                } else if stem == "lld" || stem == "rust-lld" {
-                    LinkerFlavor::Lld(sess.target.lld_flavor)
-                } else {
-                    // fall back to the value in the target spec
-                    sess.target.linker_flavor
-                };
-
-                Some((linker, flavor))
-            }
-            (None, None) => None,
-        }
-    }
-
-    // linker and linker flavor specified via command line have precedence over what the target
-    // specification specifies
-    if let Some(ret) = infer_from(sess, sess.opts.cg.linker.clone(), sess.opts.cg.linker_flavor) {
-        return ret;
-    }
-
-    if let Some(ret) = infer_from(
-        sess,
-        sess.target.linker.clone().map(PathBuf::from),
-        Some(sess.target.linker_flavor),
-    ) {
-        return ret;
-    }
-
-    bug!("Not enough information provided to determine how to invoke the linker");
-}