Target modifiers fix for bool flags without value

compiler/rustc_metadata/messages.ftl

@@ -118,12 +118,23 @@ metadata_incompatible_rustc =
 
 metadata_incompatible_target_modifiers =
     mixing `{$flag_name_prefixed}` will cause an ABI mismatch in crate `{$local_crate}`
-    .note = `{$flag_name_prefixed}={$flag_local_value}` in this crate is incompatible with `{$flag_name_prefixed}={$flag_extern_value}` in dependency `{$extern_crate}`
+    .note = `{$flag_name_prefixed}={$local_value}` in this crate is incompatible with `{$flag_name_prefixed}={$extern_value}` in dependency `{$extern_crate}`
     .help = the `{$flag_name_prefixed}` flag modifies the ABI so Rust crates compiled with different values of this flag cannot be used together safely
-
 metadata_incompatible_target_modifiers_help_allow = if you are sure this will not cause problems, you may use `-Cunsafe-allow-abi-mismatch={$flag_name}` to silence this error
-metadata_incompatible_target_modifiers_help_fix = set `{$flag_name_prefixed}={$flag_extern_value}` in this crate or `{$flag_name_prefixed}={$flag_local_value}` in `{$extern_crate}`
+metadata_incompatible_target_modifiers_help_fix = set `{$flag_name_prefixed}={$extern_value}` in this crate or `{$flag_name_prefixed}={$local_value}` in `{$extern_crate}`
+
+metadata_incompatible_target_modifiers_help_fix_l_missed = set `{$flag_name_prefixed}={$extern_value}` in this crate or unset `{$flag_name_prefixed}` in `{$extern_crate}`
 
+metadata_incompatible_target_modifiers_help_fix_r_missed = unset `{$flag_name_prefixed}` in this crate or set `{$flag_name_prefixed}={$local_value}` in `{$extern_crate}`
+
+metadata_incompatible_target_modifiers_l_missed =
+    mixing `{$flag_name_prefixed}` will cause an ABI mismatch in crate `{$local_crate}`
+    .note = unset `{$flag_name_prefixed}` in this crate is incompatible with `{$flag_name_prefixed}={$extern_value}` in dependency `{$extern_crate}`
+    .help = the `{$flag_name_prefixed}` flag modifies the ABI so Rust crates compiled with different values of this flag cannot be used together safely
+metadata_incompatible_target_modifiers_r_missed =
+    mixing `{$flag_name_prefixed}` will cause an ABI mismatch in crate `{$local_crate}`
+    .note = `{$flag_name_prefixed}={$local_value}` in this crate is incompatible with unset `{$flag_name_prefixed}` in dependency `{$extern_crate}`
+    .help = the `{$flag_name_prefixed}` flag modifies the ABI so Rust crates compiled with different values of this flag cannot be used together safely
 metadata_incompatible_wasm_link =
     `wasm_import_module` is incompatible with other arguments in `#[link]` attributes
 

compiler/rustc_metadata/src/creader.rs

@@ -358,57 +358,90 @@ impl CStore {
     ) {
         let span = krate.spans.inner_span.shrink_to_lo();
         let allowed_flag_mismatches = &tcx.sess.opts.cg.unsafe_allow_abi_mismatch;
-        let name = tcx.crate_name(LOCAL_CRATE);
+        let local_crate = tcx.crate_name(LOCAL_CRATE);
         let tmod_extender = |tmod: &TargetModifier| (tmod.extend(), tmod.clone());
         let report_diff = |prefix: &String,
                            opt_name: &String,
-                           flag_local_value: &String,
-                           flag_extern_value: &String| {
+                           flag_local_value: Option<&String>,
+                           flag_extern_value: Option<&String>| {
             if allowed_flag_mismatches.contains(&opt_name) {
                 return;
             }
-            tcx.dcx().emit_err(errors::IncompatibleTargetModifiers {
-                span,
-                extern_crate: data.name(),
-                local_crate: name,
-                flag_name: opt_name.clone(),
-                flag_name_prefixed: format!("-{}{}", prefix, opt_name),
-                flag_local_value: flag_local_value.to_string(),
-                flag_extern_value: flag_extern_value.to_string(),
-            });
+            let extern_crate = data.name();
+            let flag_name = opt_name.clone();
+            let flag_name_prefixed = format!("-{}{}", prefix, opt_name);
+
+            match (flag_local_value, flag_extern_value) {
+                (Some(local_value), Some(extern_value)) => {
+                    tcx.dcx().emit_err(errors::IncompatibleTargetModifiers {
+                        span,
+                        extern_crate,
+                        local_crate,
+                        flag_name,
+                        flag_name_prefixed,
+                        local_value: local_value.to_string(),
+                        extern_value: extern_value.to_string(),
+                    })
+                }
+                (None, Some(extern_value)) => {
+                    tcx.dcx().emit_err(errors::IncompatibleTargetModifiersLMissed {
+                        span,
+                        extern_crate,
+                        local_crate,
+                        flag_name,
+                        flag_name_prefixed,
+                        extern_value: extern_value.to_string(),
+                    })
+                }
+                (Some(local_value), None) => {
+                    tcx.dcx().emit_err(errors::IncompatibleTargetModifiersRMissed {
+                        span,
+                        extern_crate,
+                        local_crate,
+                        flag_name,
+                        flag_name_prefixed,
+                        local_value: local_value.to_string(),
+                    })
+                }
+                (None, None) => panic!("Incorrect target modifiers report_diff(None, None)"),
+            };
         };
         let mut it1 = mods.iter().map(tmod_extender);
         let mut it2 = dep_mods.iter().map(tmod_extender);
         let mut left_name_val: Option<(ExtendedTargetModifierInfo, TargetModifier)> = None;
         let mut right_name_val: Option<(ExtendedTargetModifierInfo, TargetModifier)> = None;
-        let no_val = "*".to_string();
         loop {
             left_name_val = left_name_val.or_else(|| it1.next());
             right_name_val = right_name_val.or_else(|| it2.next());
             match (&left_name_val, &right_name_val) {
                 (Some(l), Some(r)) => match l.1.opt.cmp(&r.1.opt) {
                     cmp::Ordering::Equal => {
                         if l.0.tech_value != r.0.tech_value {
-                            report_diff(&l.0.prefix, &l.0.name, &l.1.value_name, &r.1.value_name);
+                            report_diff(
+                                &l.0.prefix,
+                                &l.0.name,
+                                Some(&l.1.value_name),
+                                Some(&r.1.value_name),
+                            );
                         }
                         left_name_val = None;
                         right_name_val = None;
                     }
                     cmp::Ordering::Greater => {
-                        report_diff(&r.0.prefix, &r.0.name, &no_val, &r.1.value_name);
+                        report_diff(&r.0.prefix, &r.0.name, None, Some(&r.1.value_name));
                         right_name_val = None;
                     }
                     cmp::Ordering::Less => {
-                        report_diff(&l.0.prefix, &l.0.name, &l.1.value_name, &no_val);
+                        report_diff(&l.0.prefix, &l.0.name, Some(&l.1.value_name), None);
                         left_name_val = None;
                     }
                 },
                 (Some(l), None) => {
-                    report_diff(&l.0.prefix, &l.0.name, &l.1.value_name, &no_val);
+                    report_diff(&l.0.prefix, &l.0.name, Some(&l.1.value_name), None);
                     left_name_val = None;
                 }
                 (None, Some(r)) => {
-                    report_diff(&r.0.prefix, &r.0.name, &no_val, &r.1.value_name);
+                    report_diff(&r.0.prefix, &r.0.name, None, Some(&r.1.value_name));
                     right_name_val = None;
                 }
                 (None, None) => break,

compiler/rustc_metadata/src/errors.rs

@@ -759,8 +759,40 @@ pub struct IncompatibleTargetModifiers {
     pub local_crate: Symbol,
     pub flag_name: String,
     pub flag_name_prefixed: String,
-    pub flag_local_value: String,
-    pub flag_extern_value: String,
+    pub local_value: String,
+    pub extern_value: String,
+}
+
+#[derive(Diagnostic)]
+#[diag(metadata_incompatible_target_modifiers_l_missed)]
+#[help]
+#[note]
+#[help(metadata_incompatible_target_modifiers_help_fix_l_missed)]
+#[help(metadata_incompatible_target_modifiers_help_allow)]
+pub struct IncompatibleTargetModifiersLMissed {
+    #[primary_span]
+    pub span: Span,
+    pub extern_crate: Symbol,
+    pub local_crate: Symbol,
+    pub flag_name: String,
+    pub flag_name_prefixed: String,
+    pub extern_value: String,
+}
+
+#[derive(Diagnostic)]
+#[diag(metadata_incompatible_target_modifiers_r_missed)]
+#[help]
+#[note]
+#[help(metadata_incompatible_target_modifiers_help_fix_r_missed)]
+#[help(metadata_incompatible_target_modifiers_help_allow)]
+pub struct IncompatibleTargetModifiersRMissed {
+    #[primary_span]
+    pub span: Span,
+    pub extern_crate: Symbol,
+    pub local_crate: Symbol,
+    pub flag_name: String,
+    pub flag_name_prefixed: String,
+    pub local_value: String,
 }
 
 #[derive(Diagnostic)]

compiler/rustc_session/src/options.rs

@@ -94,45 +94,49 @@ fn tmod_push_impl(
     tmod_vals: &BTreeMap<OptionsTargetModifiers, String>,
     tmods: &mut Vec<TargetModifier>,
 ) {
-    tmods.push(TargetModifier { opt, value_name: tmod_vals.get(&opt).cloned().unwrap_or_default() })
+    if let Some(v) = tmod_vals.get(&opt) {
+        tmods.push(TargetModifier { opt, value_name: v.clone() })
+    }
 }
 
 macro_rules! tmod_push {
-    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $mods:expr, $tmod_vals:expr) => {
-        tmod_push_impl(
-            OptionsTargetModifiers::$struct_name($tmod_enum_name::$opt_name),
-            $tmod_vals,
-            $mods,
-        );
+    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $init:expr, $mods:expr, $tmod_vals:expr) => {
+        if *$opt_expr != $init {
+            tmod_push_impl(
+                OptionsTargetModifiers::$struct_name($tmod_enum_name::$opt_name),
+                $tmod_vals,
+                $mods,
+            );
+        }
     };
 }
 
 macro_rules! gather_tmods {
-    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $mods:expr, $tmod_vals:expr,
+    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $init:expr, $mods:expr, $tmod_vals:expr,
         [SUBSTRUCT], [TARGET_MODIFIER]) => {
         compile_error!("SUBSTRUCT can't be target modifier");
     };
-    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $mods:expr, $tmod_vals:expr,
+    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $init:expr, $mods:expr, $tmod_vals:expr,
         [UNTRACKED], [TARGET_MODIFIER]) => {
-        tmod_push!($struct_name, $tmod_enum_name, $opt_name, $mods, $tmod_vals)
+        tmod_push!($struct_name, $tmod_enum_name, $opt_name, $opt_expr, $init, $mods, $tmod_vals)
     };
-    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $mods:expr, $tmod_vals:expr,
+    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $init:expr, $mods:expr, $tmod_vals:expr,
         [TRACKED], [TARGET_MODIFIER]) => {
-        tmod_push!($struct_name, $tmod_enum_name, $opt_name, $mods, $tmod_vals)
+        tmod_push!($struct_name, $tmod_enum_name, $opt_name, $opt_expr, $init, $mods, $tmod_vals)
     };
-    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $mods:expr, $tmod_vals:expr,
+    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $init:expr, $mods:expr, $tmod_vals:expr,
         [TRACKED_NO_CRATE_HASH], [TARGET_MODIFIER]) => {
-        tmod_push!($struct_name, $tmod_enum_name, $opt_name, $mods, $tmod_vals)
+        tmod_push!($struct_name, $tmod_enum_name, $opt_name, $opt_expr, $init, $mods, $tmod_vals)
     };
-    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $mods:expr, $tmod_vals:expr,
+    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $init:expr, $mods:expr, $tmod_vals:expr,
         [SUBSTRUCT], []) => {
         $opt_expr.gather_target_modifiers($mods, $tmod_vals);
     };
-    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $mods:expr, $tmod_vals:expr,
+    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $init:expr, $mods:expr, $tmod_vals:expr,
         [UNTRACKED], []) => {{}};
-    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $mods:expr, $tmod_vals:expr,
+    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $init:expr, $mods:expr, $tmod_vals:expr,
         [TRACKED], []) => {{}};
-    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $mods:expr, $tmod_vals:expr,
+    ($struct_name:ident, $tmod_enum_name:ident, $opt_name:ident, $opt_expr:expr, $init:expr, $mods:expr, $tmod_vals:expr,
         [TRACKED_NO_CRATE_HASH], []) => {{}};
 }
 
@@ -474,7 +478,8 @@ macro_rules! tmod_enum {
                 $($pout)*
                 Self::$opt => {
                     let mut parsed : $t = Default::default();
-                    parse::$parse(&mut parsed, Some($puser_value));
+                    let val = if $puser_value.is_empty() { None } else { Some($puser_value) };
+                    parse::$parse(&mut parsed, val);
                     ExtendedTargetModifierInfo {
                         prefix: $prefix.to_string(),
                         name: stringify!($opt).to_string().replace('_', "-"),
@@ -569,7 +574,7 @@ macro_rules! options {
             _tmod_vals: &BTreeMap<OptionsTargetModifiers, String>,
         ) {
             $({
-                gather_tmods!($struct_name, $tmod_enum_name, $opt, &self.$opt, _mods, _tmod_vals,
+                gather_tmods!($struct_name, $tmod_enum_name, $opt, &self.$opt, $init, _mods, _tmod_vals,
                     [$dep_tracking_marker], [$($tmod),*]);
             })*
         }
@@ -681,10 +686,9 @@ fn build_options<O: Default>(
                         ),
                     }
                 }
-                if let Some(tmod) = *tmod
-                    && let Some(value) = value
-                {
-                    target_modifiers.insert(tmod, value.to_string());
+                if let Some(tmod) = *tmod {
+                    let v = value.map_or(String::new(), ToOwned::to_owned);
+                    target_modifiers.insert(tmod, v);
                 }
             }
             None => early_dcx.early_fatal(format!("unknown {outputname} option: `{key}`")),

tests/ui/target_modifiers/auxiliary/enabled_reg_struct_return.rs

@@ -0,0 +1,7 @@
+//@ no-prefer-dynamic
+//@ compile-flags: --target i686-unknown-linux-gnu -Zreg-struct-return=true
+//@ needs-llvm-components: x86
+
+#![feature(no_core)]
+#![crate_type = "rlib"]
+#![no_core]

tests/ui/target_modifiers/defaults_check.error.stderr

@@ -5,8 +5,8 @@ LL | #![feature(no_core)]
    | ^
    |
    = help: the `-Zreg-struct-return` flag modifies the ABI so Rust crates compiled with different values of this flag cannot be used together safely
-   = note: `-Zreg-struct-return=true` in this crate is incompatible with `-Zreg-struct-return=` in dependency `default_reg_struct_return`
-   = help: set `-Zreg-struct-return=` in this crate or `-Zreg-struct-return=true` in `default_reg_struct_return`
+   = note: `-Zreg-struct-return=true` in this crate is incompatible with unset `-Zreg-struct-return` in dependency `default_reg_struct_return`
+   = help: unset `-Zreg-struct-return` in this crate or set `-Zreg-struct-return=true` in `default_reg_struct_return`
    = help: if you are sure this will not cause problems, you may use `-Cunsafe-allow-abi-mismatch=reg-struct-return` to silence this error
 
 error: aborting due to 1 previous error

tests/ui/target_modifiers/no_value_bool.error.stderr

@@ -0,0 +1,13 @@
+error: mixing `-Zreg-struct-return` will cause an ABI mismatch in crate `no_value_bool`
+  --> $DIR/no_value_bool.rs:16:1
+   |
+LL | #![feature(no_core)]
+   | ^
+   |
+   = help: the `-Zreg-struct-return` flag modifies the ABI so Rust crates compiled with different values of this flag cannot be used together safely
+   = note: unset `-Zreg-struct-return` in this crate is incompatible with `-Zreg-struct-return=true` in dependency `enabled_reg_struct_return`
+   = help: set `-Zreg-struct-return=true` in this crate or unset `-Zreg-struct-return` in `enabled_reg_struct_return`
+   = help: if you are sure this will not cause problems, you may use `-Cunsafe-allow-abi-mismatch=reg-struct-return` to silence this error
+
+error: aborting due to 1 previous error
+

tests/ui/target_modifiers/no_value_bool.error_explicit.stderr

@@ -0,0 +1,13 @@
+error: mixing `-Zreg-struct-return` will cause an ABI mismatch in crate `no_value_bool`
+  --> $DIR/no_value_bool.rs:16:1
+   |
+LL | #![feature(no_core)]
+   | ^
+   |
+   = help: the `-Zreg-struct-return` flag modifies the ABI so Rust crates compiled with different values of this flag cannot be used together safely
+   = note: unset `-Zreg-struct-return` in this crate is incompatible with `-Zreg-struct-return=true` in dependency `enabled_reg_struct_return`
+   = help: set `-Zreg-struct-return=true` in this crate or unset `-Zreg-struct-return` in `enabled_reg_struct_return`
+   = help: if you are sure this will not cause problems, you may use `-Cunsafe-allow-abi-mismatch=reg-struct-return` to silence this error
+
+error: aborting due to 1 previous error
+

tests/ui/target_modifiers/no_value_bool.rs

@@ -0,0 +1,22 @@
+// Tests that bool target modifier value (true) in dependency crate is ok linked
+// with the -Zflag specified without value (-Zflag=true is consistent with -Zflag)
+
+//@ aux-build:enabled_reg_struct_return.rs
+//@ compile-flags: --target i686-unknown-linux-gnu -Cpanic=abort
+//@ needs-llvm-components: x86
+
+//@ revisions: ok ok_explicit error error_explicit
+//@[ok] compile-flags: -Zreg-struct-return
+//@[ok_explicit] compile-flags: -Zreg-struct-return=true
+//@[error] compile-flags:
+//@[error_explicit] compile-flags: -Zreg-struct-return=false
+//@[ok] check-pass
+//@[ok_explicit] check-pass
+
+#![feature(no_core)]
+//[error]~^ ERROR mixing `-Zreg-struct-return` will cause an ABI mismatch in crate `no_value_bool`
+//[error_explicit]~^^ ERROR mixing `-Zreg-struct-return` will cause an ABI mismatch in crate `no_value_bool`
+#![crate_type = "rlib"]
+#![no_core]
+
+extern crate enabled_reg_struct_return;