Fix CI failures on windows and aarch64-linux

Author: petrochenkov

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -2403,6 +2403,14 @@ fn add_upstream_rust_crates<'a>(
                                 bundle: Some(false),
                                 whole_archive: Some(false) | None,
                             } => {
+                                // HACK/FIXME: Fixup a circular dependency between libgcc and libc
+                                // with glibc. This logic should be moved to the libc crate.
+                                if sess.target.os == "linux"
+                                    && sess.target.env == "gnu"
+                                    && name == "c"
+                                {
+                                    cmd.link_staticlib("gcc", false);
+                                }
                                 cmd.link_staticlib(name, lib.verbatim.unwrap_or(false));
                             }
                             NativeLibKind::LinkArg => {

compiler/rustc_codegen_ssa/src/base.rs

@@ -849,26 +849,34 @@ impl CrateInfo {
 
         // Handle circular dependencies in the standard library.
         // See comment before `add_linked_symbol_object` function for the details.
-        let missing_weak_lang_items: FxHashSet<&Symbol> = info
-            .used_crates
-            .iter()
-            .flat_map(|cnum| {
-                tcx.missing_lang_items(*cnum)
-                    .iter()
-                    .filter(|l| lang_items::required(tcx, **l))
-                    .filter_map(|item| WEAK_ITEMS_SYMBOLS.get(item))
-            })
-            .collect();
-        info.linked_symbols
-            .iter_mut()
-            .filter(|(crate_type, _)| !matches!(crate_type, CrateType::Rlib | CrateType::Staticlib))
-            .for_each(|(_, linked_symbols)| {
-                linked_symbols.extend(
-                    missing_weak_lang_items
+        // With msvc-like linkers it's both unnecessary (they support circular dependencies),
+        // and causes linking issues (when weak lang item symbols are "privatized" by LTO).
+        let target = &tcx.sess.target;
+        if !target.is_like_msvc {
+            let missing_weak_lang_items: FxHashSet<&Symbol> = info
+                .used_crates
+                .iter()
+                .flat_map(|cnum| {
+                    tcx.missing_lang_items(*cnum)
                         .iter()
-                        .map(|item| (item.to_string(), SymbolExportKind::Text)),
-                )
-            });
+                        .filter(|l| lang_items::required(tcx, **l))
+                        .filter_map(|item| WEAK_ITEMS_SYMBOLS.get(item))
+                })
+                .collect();
+            let prefix = if target.is_like_windows && target.arch == "x86" { "_" } else { "" };
+            info.linked_symbols
+                .iter_mut()
+                .filter(|(crate_type, _)| {
+                    !matches!(crate_type, CrateType::Rlib | CrateType::Staticlib)
+                })
+                .for_each(|(_, linked_symbols)| {
+                    linked_symbols.extend(
+                        missing_weak_lang_items
+                            .iter()
+                            .map(|item| (format!("{prefix}{item}"), SymbolExportKind::Text)),
+                    )
+                });
+        }
 
         let embed_visualizers = tcx.sess.crate_types().iter().any(|&crate_type| match crate_type {
             CrateType::Executable | CrateType::Dylib | CrateType::Cdylib => {
@@ -888,7 +896,7 @@ impl CrateInfo {
             }
         });
 
-        if tcx.sess.target.is_like_msvc && embed_visualizers {
+        if target.is_like_msvc && embed_visualizers {
             info.natvis_debugger_visualizers =
                 collect_debugger_visualizers_transitive(tcx, DebuggerVisualizerType::Natvis);
         }