Target modifiers (special marked options) are recorded in metainfo and compared to be equal in different crates

Author: azhogin

compiler/rustc_driver_impl/src/lib.rs

@@ -1170,11 +1170,12 @@ fn describe_codegen_flags() {
 
 fn print_flag_list<T>(
     cmdline_opt: &str,
-    flag_list: &[(&'static str, T, &'static str, &'static str)],
+    flag_list: &[(&'static str, T, &'static str, &'static str, bool)],
 ) {
-    let max_len = flag_list.iter().map(|&(name, _, _, _)| name.chars().count()).max().unwrap_or(0);
+    let max_len =
+        flag_list.iter().map(|&(name, _, _, _, _)| name.chars().count()).max().unwrap_or(0);
 
-    for &(name, _, _, desc) in flag_list {
+    for &(name, _, _, desc, _) in flag_list {
         safe_println!(
             "    {} {:>width$}=val -- {}",
             cmdline_opt,

compiler/rustc_interface/src/passes.rs

@@ -270,6 +270,7 @@ fn configure_and_expand(
 
     resolver.resolve_crate(&krate);
 
+    CStore::from_tcx(tcx).report_incompatible_target_modifiers(tcx, &krate, resolver.lint_buffer());
     krate
 }
 

compiler/rustc_lint/messages.ftl

@@ -414,6 +414,13 @@ lint_improper_ctypes_union_layout_help = consider adding a `#[repr(C)]` or `#[re
 lint_improper_ctypes_union_layout_reason = this union has unspecified layout
 lint_improper_ctypes_union_non_exhaustive = this union is non-exhaustive
 
+lint_incompatible_target_modifiers =
+    mixing `{$flag_name_prefixed}` will cause an ABI mismatch
+    .note1 = `{$flag_name_prefixed}={$flag_local_value}` in this crate is incompatible with `{$flag_name_prefixed}={$flag_extern_value}` in dependency `{$extern_crate}`
+    .help = `{$flag_name_prefixed}` modifies the ABI and Rust crates compiled with different values of this flag cannot be used together safely
+    .suggestion = set `{$flag_name_prefixed}=${flag_extern_value}` in this crate or `{$flag_name_prefixed}=${flag_local_value}` in `{$extern_crate}`
+    .note2 = alternatively, use `-Cunsafe-allow-abi-mismatch={$flag_name}` to silence this error
+
 lint_incomplete_include =
     include macro expected single expression in source
 

compiler/rustc_lint/src/context/diagnostics.rs

@@ -422,6 +422,22 @@ pub(super) fn decorate_lint(sess: &Session, diagnostic: BuiltinLintDiag, diag: &
             lints::UnusedCrateDependency { extern_crate, local_crate }.decorate_lint(diag)
         }
         BuiltinLintDiag::WasmCAbi => lints::WasmCAbi.decorate_lint(diag),
+        BuiltinLintDiag::IncompatibleTargetModifiers {
+            extern_crate,
+            local_crate,
+            flag_name,
+            flag_name_prefixed,
+            flag_local_value,
+            flag_extern_value,
+        } => lints::IncompatibleTargetModifiers {
+            extern_crate,
+            local_crate,
+            flag_name,
+            flag_name_prefixed,
+            flag_local_value,
+            flag_extern_value,
+        }
+        .decorate_lint(diag),
         BuiltinLintDiag::IllFormedAttributeInput { suggestions } => {
             lints::IllFormedAttributeInput {
                 num_suggestions: suggestions.len(),

compiler/rustc_lint/src/lints.rs

@@ -2474,6 +2474,20 @@ pub(crate) struct UnusedCrateDependency {
     pub local_crate: Symbol,
 }
 
+#[derive(LintDiagnostic)]
+#[diag(lint_incompatible_target_modifiers)]
+#[help]
+#[note(lint_note1)]
+#[note(lint_note2)]
+pub(crate) struct IncompatibleTargetModifiers {
+    pub extern_crate: Symbol,
+    pub local_crate: Symbol,
+    pub flag_name: String,
+    pub flag_name_prefixed: String,
+    pub flag_local_value: String,
+    pub flag_extern_value: String,
+}
+
 #[derive(LintDiagnostic)]
 #[diag(lint_wasm_c_abi)]
 pub(crate) struct WasmCAbi;

compiler/rustc_lint_defs/src/builtin.rs

@@ -50,6 +50,7 @@ declare_lint_pass! {
         FUZZY_PROVENANCE_CASTS,
         HIDDEN_GLOB_REEXPORTS,
         ILL_FORMED_ATTRIBUTE_INPUT,
+        INCOMPATIBLE_TARGET_MODIFIERS,
         INCOMPLETE_INCLUDE,
         INEFFECTIVE_UNSTABLE_TRAIT_IMPL,
         INLINE_NO_SANITIZE,
@@ -582,6 +583,46 @@ declare_lint! {
     crate_level_only
 }
 
+declare_lint! {
+    /// The `incompatible_target_modifiers` lint detects crates with incompatible target modifiers
+    /// (abi-changing or vulnerability-affecting flags).
+    ///
+    /// ### Example
+    ///
+    /// ```rust,ignore (needs extern crate)
+    /// #![deny(incompatible_target_modifiers)]
+    /// ```
+    ///
+    /// When main and dependency crates are compiled with `-Zregparm=1` and `-Zregparm=2` correspondingly.
+    ///
+    /// This will produce:
+    ///
+    /// ```text
+    /// error: mixing `-Zregparm` will cause an ABI mismatch
+    ///   --> $DIR/incompatible_regparm.rs:12:1
+    ///    |
+    /// LL | #![crate_type = "lib"]
+    ///    | ^
+    ///    |
+    ///    = help: `-Zregparm` modifies the ABI and Rust crates compiled with different values of this flag cannot be used together safely
+    ///    = note: `-Zregparm=1` in this crate is incompatible with `-Zregparm=2` in dependency `wrong_regparm`
+    ///    = note: alternatively, use `-Cunsafe-allow-abi-mismatch=regparm` to silence this error
+    ///    = note: `#[deny(incompatible_target_modifiers)]` on by default
+    /// ```
+    ///
+    /// ### Explanation
+    ///
+    /// `Target modifiers` are compilation flags that affects abi or vulnerability resistance.
+    /// Linking together crates with incompatible target modifiers would produce incorrect code
+    /// or degradation of vulnerability resistance.
+    /// So this lint should find such inconsistency.
+    ///
+    pub INCOMPATIBLE_TARGET_MODIFIERS,
+    Deny,
+    "Incompatible target modifiers",
+    crate_level_only
+}
+
 declare_lint! {
     /// The `unused_qualifications` lint detects unnecessarily qualified
     /// names.

compiler/rustc_lint_defs/src/lib.rs

@@ -768,6 +768,14 @@ pub enum BuiltinLintDiag {
     AvoidUsingIntelSyntax,
     AvoidUsingAttSyntax,
     IncompleteInclude,
+    IncompatibleTargetModifiers {
+        extern_crate: Symbol,
+        local_crate: Symbol,
+        flag_name: String,
+        flag_name_prefixed: String,
+        flag_local_value: String,
+        flag_extern_value: String,
+    },
     UnnameableTestItems,
     DuplicateMacroAttribute,
     CfgAttrNoAttributes,

compiler/rustc_metadata/src/creader.rs

@@ -22,9 +22,9 @@ use rustc_hir::definitions::Definitions;
 use rustc_index::IndexVec;
 use rustc_middle::bug;
 use rustc_middle::ty::{TyCtxt, TyCtxtFeed};
-use rustc_session::config::{self, CrateType, ExternLocation};
+use rustc_session::config::{self, CrateType, ExternLocation, TargetModifier};
 use rustc_session::cstore::{CrateDepKind, CrateSource, ExternCrate, ExternCrateSource};
-use rustc_session::lint::{self, BuiltinLintDiag};
+use rustc_session::lint::{self, BuiltinLintDiag, LintBuffer};
 use rustc_session::output::validate_crate_name;
 use rustc_session::search_paths::PathKind;
 use rustc_span::edition::Edition;
@@ -35,7 +35,9 @@ use tracing::{debug, info, trace};
 
 use crate::errors;
 use crate::locator::{CrateError, CrateLocator, CratePaths};
-use crate::rmeta::{CrateDep, CrateMetadata, CrateNumMap, CrateRoot, MetadataBlob};
+use crate::rmeta::{
+    CrateDep, CrateMetadata, CrateNumMap, CrateRoot, MetadataBlob, TargetModifiers,
+};
 
 /// The backend's way to give the crate store access to the metadata in a library.
 /// Note that it returns the raw metadata bytes stored in the library file, whether
@@ -290,6 +292,98 @@ impl CStore {
         }
     }
 
+    pub fn report_incompatible_target_modifiers(
+        &self,
+        tcx: TyCtxt<'_>,
+        krate: &Crate,
+        lints: &mut LintBuffer,
+    ) {
+        if tcx.crate_types().contains(&CrateType::ProcMacro) {
+            return;
+        }
+        let sess = tcx.sess;
+        let empty_vec = Vec::<String>::new();
+        let allowed_flag_mismatches = match sess.opts.cg.unsafe_allow_abi_mismatch.as_ref() {
+            Some(vec) => {
+                if vec.is_empty() {
+                    // Setting `-Zunsafe-allow-abi-mismatch=` to an empty
+                    // value allows all target modifier mismatches.
+                    return;
+                }
+                vec
+            }
+            None => &empty_vec,
+        };
+        let span = krate.spans.inner_span.shrink_to_lo();
+
+        let name = tcx.crate_name(LOCAL_CRATE);
+        let mods = sess.opts.gather_target_modifiers();
+        for (_cnum, data) in self.iter_crate_data() {
+            if data.is_proc_macro_crate() {
+                continue;
+            }
+            let mut report_diff = |opt_name_hash: u64,
+                                   flag_local_value: &String,
+                                   flag_extern_value: &String| {
+                let name_info = sess.opts.target_modifier_info_by_hash(opt_name_hash);
+                let (prefix, opt_name) = name_info.expect("Target modifier not found by name hash");
+                if allowed_flag_mismatches.contains(&opt_name) {
+                    return;
+                }
+                lints.buffer_lint(
+                    lint::builtin::INCOMPATIBLE_TARGET_MODIFIERS,
+                    ast::CRATE_NODE_ID,
+                    span,
+                    BuiltinLintDiag::IncompatibleTargetModifiers {
+                        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 mut it1 = mods.iter();
+            let mut it2 = data.target_modifiers();
+            let mut left_name_val: Option<TargetModifier> = None;
+            let mut right_name_val: Option<TargetModifier> = None;
+            let no_val = "*".to_string();
+            loop {
+                left_name_val = left_name_val.or_else(|| it1.next().cloned());
+                right_name_val = right_name_val.or_else(|| it2.next().cloned());
+                match (&left_name_val, &right_name_val) {
+                    (Some(l), Some(r)) => match l.name_hash.cmp(&r.name_hash) {
+                        cmp::Ordering::Equal => {
+                            if l.value_code != r.value_code {
+                                report_diff(l.name_hash, &l.value_name, &r.value_name);
+                            }
+                            left_name_val = None;
+                            right_name_val = None;
+                        }
+                        cmp::Ordering::Greater => {
+                            report_diff(r.name_hash, &no_val, &r.value_name);
+                            right_name_val = None;
+                        }
+                        cmp::Ordering::Less => {
+                            report_diff(l.name_hash, &l.value_name, &no_val);
+                            left_name_val = None;
+                        }
+                    },
+                    (Some(l), None) => {
+                        report_diff(l.name_hash, &l.value_name, &no_val);
+                        left_name_val = None;
+                    }
+                    (None, Some(r)) => {
+                        report_diff(r.name_hash, &no_val, &r.value_name);
+                        right_name_val = None;
+                    }
+                    (None, None) => break,
+                }
+            }
+        }
+    }
+
     pub fn new(metadata_loader: Box<MetadataLoaderDyn>) -> CStore {
         CStore {
             metadata_loader,
@@ -432,6 +526,7 @@ impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
         };
 
         let cnum_map = self.resolve_crate_deps(root, &crate_root, &metadata, cnum, dep_kind)?;
+        let target_modifiers = self.resolve_target_modifiers(&crate_root, &metadata, cnum)?;
 
         let raw_proc_macros = if crate_root.is_proc_macro_crate() {
             let temp_root;
@@ -456,6 +551,7 @@ impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
             raw_proc_macros,
             cnum,
             cnum_map,
+            target_modifiers,
             dep_kind,
             source,
             private_dep,
@@ -694,6 +790,25 @@ impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
         Ok(crate_num_map)
     }
 
+    fn resolve_target_modifiers(
+        &mut self,
+        crate_root: &CrateRoot,
+        metadata: &MetadataBlob,
+        krate: CrateNum,
+    ) -> Result<TargetModifiers, CrateError> {
+        debug!("resolving target modifiers of external crate");
+        if crate_root.is_proc_macro_crate() {
+            return Ok(TargetModifiers::new());
+        }
+        let mods = crate_root.decode_target_modifiers(metadata);
+        let mut target_modifiers = TargetModifiers::with_capacity(mods.len());
+        for modifier in mods {
+            target_modifiers.push(modifier);
+        }
+        debug!("resolve_target_modifiers: target mods for {:?} is {:?}", krate, target_modifiers);
+        Ok(target_modifiers)
+    }
+
     fn dlsym_proc_macros(
         &self,
         path: &Path,

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -29,6 +29,7 @@ use rustc_middle::{bug, implement_ty_decoder};
 use rustc_serialize::opaque::MemDecoder;
 use rustc_serialize::{Decodable, Decoder};
 use rustc_session::Session;
+use rustc_session::config::TargetModifier;
 use rustc_session::cstore::{CrateSource, ExternCrate};
 use rustc_span::hygiene::HygieneDecodeContext;
 use rustc_span::symbol::kw;
@@ -74,6 +75,9 @@ impl MetadataBlob {
 /// own crate numbers.
 pub(crate) type CrateNumMap = IndexVec<CrateNum, CrateNum>;
 
+/// Target modifiers - abi / vulnerability-resist affecting flags
+pub(crate) type TargetModifiers = Vec<TargetModifier>;
+
 pub(crate) struct CrateMetadata {
     /// The primary crate data - binary metadata blob.
     blob: MetadataBlob,
@@ -111,6 +115,8 @@ pub(crate) struct CrateMetadata {
     cnum_map: CrateNumMap,
     /// Same ID set as `cnum_map` plus maybe some injected crates like panic runtime.
     dependencies: Vec<CrateNum>,
+    /// Target modifiers - abi and vulnerability-resist affecting flags the crate was compiled with
+    target_modifiers: TargetModifiers,
     /// How to link (or not link) this crate to the currently compiled crate.
     dep_kind: CrateDepKind,
     /// Filesystem location of this crate.
@@ -961,6 +967,13 @@ impl CrateRoot {
     ) -> impl ExactSizeIterator<Item = CrateDep> + Captures<'a> {
         self.crate_deps.decode(metadata)
     }
+
+    pub(crate) fn decode_target_modifiers<'a>(
+        &self,
+        metadata: &'a MetadataBlob,
+    ) -> impl ExactSizeIterator<Item = TargetModifier> + Captures<'a> {
+        self.target_modifiers.decode(metadata)
+    }
 }
 
 impl<'a> CrateMetadataRef<'a> {
@@ -1818,6 +1831,7 @@ impl CrateMetadata {
         raw_proc_macros: Option<&'static [ProcMacro]>,
         cnum: CrateNum,
         cnum_map: CrateNumMap,
+        target_modifiers: TargetModifiers,
         dep_kind: CrateDepKind,
         source: CrateSource,
         private_dep: bool,
@@ -1849,6 +1863,7 @@ impl CrateMetadata {
             cnum,
             cnum_map,
             dependencies,
+            target_modifiers,
             dep_kind,
             source: Lrc::new(source),
             private_dep,
@@ -1878,6 +1893,10 @@ impl CrateMetadata {
         self.dependencies.push(cnum);
     }
 
+    pub(crate) fn target_modifiers(&self) -> impl Iterator<Item = &TargetModifier> + '_ {
+        self.target_modifiers.iter()
+    }
+
     pub(crate) fn update_extern_crate(&mut self, new_extern_crate: ExternCrate) -> bool {
         let update =
             Some(new_extern_crate.rank()) > self.extern_crate.as_ref().map(ExternCrate::rank);