remove -Csoft-float

Author: RalfJung

compiler/rustc_codegen_llvm/src/back/write.rs

@@ -24,9 +24,7 @@ use rustc_middle::ty::TyCtxt;
 use rustc_session::Session;
 use rustc_session::config::{self, Lto, OutputType, Passes, SplitDwarfKind, SwitchWithOptPath};
 use rustc_span::{BytePos, InnerSpan, Pos, RemapPathScopeComponents, SpanData, SyntaxContext, sym};
-use rustc_target::spec::{
-    Arch, CodeModel, FloatAbi, RelocModel, SanitizerSet, SplitDebuginfo, TlsModel,
-};
+use rustc_target::spec::{CodeModel, FloatAbi, RelocModel, SanitizerSet, SplitDebuginfo, TlsModel};
 use tracing::{debug, trace};
 
 use crate::back::lto::ThinBuffer;
@@ -207,13 +205,7 @@ pub(crate) fn target_machine_factory(
     let reloc_model = to_llvm_relocation_model(sess.relocation_model());
 
     let (opt_level, _) = to_llvm_opt_settings(optlvl);
-    let float_abi = if sess.target.arch == Arch::Arm && sess.opts.cg.soft_float {
-        llvm::FloatAbi::Soft
-    } else {
-        // `validate_commandline_args_with_session_available` has already warned about this being
-        // ignored. Let's make sure LLVM doesn't suddenly start using this flag on more targets.
-        to_llvm_float_abi(sess.target.llvm_floatabi)
-    };
+    let float_abi = to_llvm_float_abi(sess.target.llvm_floatabi);
 
     let ffunction_sections =
         sess.opts.unstable_opts.function_sections.unwrap_or(sess.target.function_sections);

compiler/rustc_interface/src/tests.rs

@@ -637,7 +637,6 @@ fn test_codegen_options_tracking_hash() {
     tracked!(profile_use, Some(PathBuf::from("abc")));
     tracked!(relocation_model, Some(RelocModel::Pic));
     tracked!(relro_level, Some(RelroLevel::Full));
-    tracked!(soft_float, true);
     tracked!(split_debuginfo, Some(SplitDebuginfo::Packed));
     tracked!(symbol_mangling_version, Some(SymbolManglingVersion::V0));
     tracked!(target_cpu, Some(String::from("abc")));

compiler/rustc_session/src/errors.rs

@@ -517,17 +517,6 @@ pub(crate) struct FailedToCreateProfiler {
     pub(crate) err: String,
 }
 
-#[derive(Diagnostic)]
-#[diag("`-Csoft-float` is ignored on this target; it only has an effect on *eabihf targets")]
-#[note("this may become a hard error in a future version of Rust")]
-pub(crate) struct SoftFloatIgnored;
-
-#[derive(Diagnostic)]
-#[diag("`-Csoft-float` is unsound and deprecated; use a corresponding *eabi target instead")]
-#[note("it will be removed or ignored in a future version of Rust")]
-#[note("see issue #129893 <https://github.com/rust-lang/rust/issues/129893> for more information")]
-pub(crate) struct SoftFloatDeprecated;
-
 #[derive(LintDiagnostic)]
 #[diag("unexpected `--cfg {$cfg}` flag")]
 #[note("config `{$cfg_name}` is only supposed to be controlled by `{$controlled_by}`")]

compiler/rustc_session/src/options.rs

@@ -611,7 +611,7 @@ macro_rules! options {
         $parse:ident,
         [$dep_tracking_marker:ident $( $tmod:ident )?],
         $desc:expr
-        $(, deprecated_do_nothing: $dnn:literal )?)
+        $(, is_deprecated_and_do_nothing: $dnn:literal )?)
      ),* ,) =>
 (
     #[derive(Clone)]
@@ -758,6 +758,11 @@ fn build_options<O: Default>(
                 }
                 if !setter(&mut op, value) {
                     match value {
+                        _ if *type_desc == desc::parse_error => early_dcx.early_fatal(
+                            format!(
+                                "{outputname} option `{key}` has been removed"
+                            ),
+                        ),
                         None => early_dcx.early_fatal(
                             format!(
                                 "{outputname} option `{key}` requires {type_desc} ({prefix} {key}=<value>)"
@@ -783,6 +788,7 @@ fn build_options<O: Default>(
 
 #[allow(non_upper_case_globals)]
 mod desc {
+    pub(crate) const parse_error: &str = "<removed>";
     pub(crate) const parse_no_value: &str = "no value";
     pub(crate) const parse_bool: &str =
         "one of: `y`, `yes`, `on`, `true`, `n`, `no`, `off` or `false`";
@@ -889,6 +895,11 @@ pub mod parse {
     pub(crate) use super::*;
     pub(crate) const MAX_THREADS_CAP: usize = 256;
 
+    /// THis is always an error. Used for removed options.
+    pub(crate) fn parse_error(_slot: &mut (), _v: Option<&str>) -> bool {
+        false
+    }
+
     /// This is for boolean options that don't take a value, and are true simply
     /// by existing on the command-line.
     ///
@@ -2059,7 +2070,7 @@ options! {
     #[rustc_lint_opt_deny_field_access("documented to do nothing")]
     ar: String = (String::new(), parse_string, [UNTRACKED],
         "this option is deprecated and does nothing",
-        deprecated_do_nothing: true),
+        is_deprecated_and_do_nothing: true),
     #[rustc_lint_opt_deny_field_access("use `Session::code_model` instead of this field")]
     code_model: Option<CodeModel> = (None, parse_code_model, [TRACKED],
         "choose the code model to use (`rustc --print code-models` for details)"),
@@ -2098,7 +2109,7 @@ options! {
     inline_threshold: Option<u32> = (None, parse_opt_number, [UNTRACKED],
         "this option is deprecated and does nothing \
         (consider using `-Cllvm-args=--inline-threshold=...`)",
-        deprecated_do_nothing: true),
+        is_deprecated_and_do_nothing: true),
     #[rustc_lint_opt_deny_field_access("use `Session::instrument_coverage` instead of this field")]
     instrument_coverage: InstrumentCoverage = (InstrumentCoverage::No, parse_instrument_coverage, [TRACKED],
         "instrument the generated code to support LLVM source-based code coverage reports \
@@ -2139,7 +2150,7 @@ options! {
     #[rustc_lint_opt_deny_field_access("documented to do nothing")]
     no_stack_check: bool = (false, parse_no_value, [UNTRACKED],
         "this option is deprecated and does nothing",
-        deprecated_do_nothing: true),
+        is_deprecated_and_do_nothing: true),
     no_vectorize_loops: bool = (false, parse_no_value, [TRACKED],
         "disable loop vectorization optimization passes"),
     no_vectorize_slp: bool = (false, parse_no_value, [TRACKED],
@@ -2173,8 +2184,10 @@ options! {
         "set rpath values in libs/exes (default: no)"),
     save_temps: bool = (false, parse_bool, [UNTRACKED],
         "save all temporary output files during compilation (default: no)"),
-    soft_float: bool = (false, parse_bool, [TRACKED],
-        "deprecated option: use soft float ABI (*eabihf targets only) (default: no)"),
+    #[rustc_lint_opt_deny_field_access("documented to do nothing")]
+    soft_float: () = ((), parse_error, [UNTRACKED],
+        "this option is deprecated and does nothing \
+        (use a corresponding *eabi target instead)"),
     #[rustc_lint_opt_deny_field_access("use `Session::split_debuginfo` instead of this field")]
     split_debuginfo: Option<SplitDebuginfo> = (None, parse_split_debuginfo, [TRACKED],
         "how to handle split-debuginfo, a platform-specific option"),

compiler/rustc_session/src/session.rs

@@ -1346,16 +1346,6 @@ fn validate_commandline_args_with_session_available(sess: &Session) {
             }
         }
     }
-
-    if sess.opts.cg.soft_float {
-        if sess.target.arch == Arch::Arm {
-            sess.dcx().emit_warn(errors::SoftFloatDeprecated);
-        } else {
-            // All `use_softfp` does is the equivalent of `-mfloat-abi` in GCC/clang, which only exists on ARM targets.
-            // We document this flag to only affect `*eabihf` targets, so let's show a warning for all other targets.
-            sess.dcx().emit_warn(errors::SoftFloatIgnored);
-        }
-    }
 }
 
 /// Holds data on the current incremental compilation session, if there is one.