use LinkerFlavorCli for -C linker-flavor

Author: lqd

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -1130,7 +1130,7 @@ pub fn ignored_for_lto(sess: &Session, info: &CrateInfo, cnum: CrateNum) -> bool
         && (info.compiler_builtins == Some(cnum) || info.is_no_builtins.contains(&cnum))
 }
 
-// This functions tries to determine the appropriate linker (and corresponding LinkerFlavor) to use
+/// This function tries to determine the appropriate linker (and corresponding LinkerFlavor) to use
 pub fn linker_and_flavor(sess: &Session) -> (PathBuf, LinkerFlavor) {
     fn infer_from(
         sess: &Session,
@@ -1203,9 +1203,13 @@ pub fn linker_and_flavor(sess: &Session) -> (PathBuf, LinkerFlavor) {
         }
     }
 
-    // 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) {
+    // Lower the potential `-C linker-flavor` CLI flag to its principal linker-flavor
+    let linker_flavor =
+        sess.opts.cg.linker_flavor.as_ref().map(|surface_flavor| surface_flavor.to_flavor());
+
+    // The `-C linker` and `-C linker-flavor` CLI flags have higher priority than what the target
+    // specification declares.
+    if let Some(ret) = infer_from(sess, sess.opts.cg.linker.clone(), linker_flavor) {
         return ret;
     }
 

compiler/rustc_interface/src/tests.rs

@@ -3,6 +3,7 @@ use crate::interface::parse_cfgspecs;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::{emitter::HumanReadableErrorType, registry, ColorConfig};
 use rustc_session::config::InstrumentCoverage;
+use rustc_session::config::LinkerFlavorCli;
 use rustc_session::config::Strip;
 use rustc_session::config::{build_configuration, build_session_options, to_crate_config};
 use rustc_session::config::{
@@ -551,7 +552,7 @@ fn test_codegen_options_tracking_hash() {
     untracked!(link_args, vec![String::from("abc"), String::from("def")]);
     untracked!(link_self_contained, Some(true));
     untracked!(linker, Some(PathBuf::from("linker")));
-    untracked!(linker_flavor, Some(LinkerFlavor::Gcc));
+    untracked!(linker_flavor, Some(LinkerFlavorCli::WellKnown(LinkerFlavor::Gcc)));
     untracked!(no_stack_check, true);
     untracked!(remark, Passes::Some(vec![String::from("pass1"), String::from("pass2")]));
     untracked!(rpath, true);

compiler/rustc_session/src/config.rs

@@ -2432,7 +2432,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
         }
     }
 
-    if cg.linker_flavor == Some(LinkerFlavor::L4Bender)
+    if cg.linker_flavor == Some(LinkerFlavorCli::WellKnown(LinkerFlavor::L4Bender))
         && !nightly_options::is_unstable_enabled(matches)
     {
         early_error(

compiler/rustc_session/src/options.rs

@@ -5,7 +5,7 @@ use crate::lint;
 use crate::search_paths::SearchPath;
 use crate::utils::NativeLib;
 use rustc_errors::LanguageIdentifier;
-use rustc_target::spec::{CodeModel, LinkerFlavor, MergeFunctions, PanicStrategy, SanitizerSet};
+use rustc_target::spec::{CodeModel, MergeFunctions, PanicStrategy, SanitizerSet};
 use rustc_target::spec::{
     RelocModel, RelroLevel, SplitDebuginfo, StackProtector, TargetTriple, TlsModel,
 };
@@ -383,7 +383,9 @@ mod desc {
         "either a boolean (`yes`, `no`, `on`, `off`, etc), `checks`, or `nochecks`";
     pub const parse_cfprotection: &str = "`none`|`no`|`n` (default), `branch`, `return`, or `full`|`yes`|`y` (equivalent to `branch` and `return`)";
     pub const parse_strip: &str = "either `none`, `debuginfo`, or `symbols`";
-    pub const parse_linker_flavor: &str = ::rustc_target::spec::LinkerFlavor::one_of();
+    pub const parse_linker_flavor: &str = "one of: `em`, `gcc`, `l4-bender`, `ld`, `msvc`, \
+        `ptx-linker`, `bpf-linker`, `wasm-ld`, `ld64.lld`, `ld.lld`, `lld-link`, \
+        or a `gcc:`-prefixed linker to use with the gcc flavor, like `gcc:lld` or `gcc:gold,`";
     pub const parse_optimization_fuel: &str = "crate=integer";
     pub const parse_mir_spanview: &str = "`statement` (default), `terminator`, or `block`";
     pub const parse_instrument_coverage: &str =
@@ -760,8 +762,8 @@ mod parse {
         true
     }
 
-    pub(crate) fn parse_linker_flavor(slot: &mut Option<LinkerFlavor>, v: Option<&str>) -> bool {
-        match v.and_then(LinkerFlavor::from_str) {
+    pub(crate) fn parse_linker_flavor(slot: &mut Option<LinkerFlavorCli>, v: Option<&str>) -> bool {
+        match v.and_then(|s| LinkerFlavorCli::from_str(s).ok()) {
             Some(lf) => *slot = Some(lf),
             _ => return false,
         }
@@ -1120,7 +1122,7 @@ options! {
         on C toolchain installed in the system"),
     linker: Option<PathBuf> = (None, parse_opt_pathbuf, [UNTRACKED],
         "system linker to link outputs with"),
-    linker_flavor: Option<LinkerFlavor> = (None, parse_linker_flavor, [UNTRACKED],
+    linker_flavor: Option<LinkerFlavorCli> = (None, parse_linker_flavor, [UNTRACKED],
         "linker flavor"),
     linker_plugin_lto: LinkerPluginLto = (LinkerPluginLto::Disabled,
         parse_linker_plugin_lto, [TRACKED],

compiler/rustc_target/src/spec/mod.rs

@@ -165,6 +165,10 @@ macro_rules! flavor_mappings {
     )
 }
 
+// Note: until string concatenation can be done in const contexts, remember to update the
+// `parse_linker_flavor` error message in rustc_session/src/options.rs whenever adding a new allowed
+// value here, since it also mentions enriched CLI-allowed values like `gcc:lld` that are then
+// lowered to these target specs `LinkerFlavor`s.
 flavor_mappings! {
     ((LinkerFlavor::Em), "em"),
     ((LinkerFlavor::Gcc), "gcc"),