diff --git a/CHANGELOG.md b/CHANGELOG.md
index 490b555df84..4c31ec59641 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -25,6 +25,10 @@
 - Windows GNU targets now copy `.dll.a` import library files for DLL crate
   types to the output directory.
   [#8141](https://github.com/rust-lang/cargo/pull/8141)
+- Dylibs for all dependencies are now unconditionally copied to the output
+  directory. Some obscure scenarios can cause an old dylib to be referenced
+  between builds, and this ensures that all the latest copies are used.
+  [#8139](https://github.com/rust-lang/cargo/pull/8139)
 
 ### Fixed
 - Fixed copying Windows `.pdb` files to the output directory when the filename
diff --git a/src/cargo/core/compiler/context/compilation_files.rs b/src/cargo/core/compiler/context/compilation_files.rs
index fac6564a1c9..9fc2f4117a4 100644
--- a/src/cargo/core/compiler/context/compilation_files.rs
+++ b/src/cargo/core/compiler/context/compilation_files.rs
@@ -133,7 +133,7 @@ impl<'a, 'cfg: 'a> CompilationFiles<'a, 'cfg> {
             .map(|unit| (unit, LazyCell::new()))
             .collect();
         CompilationFiles {
-            ws: &cx.bcx.ws,
+            ws: cx.bcx.ws,
             host,
             target,
             export_dir: cx.bcx.build_config.export_dir.clone(),
diff --git a/src/cargo/core/manifest.rs b/src/cargo/core/manifest.rs
index 6ed4f1deaa9..c5c15a4a8b0 100644
--- a/src/cargo/core/manifest.rs
+++ b/src/cargo/core/manifest.rs
@@ -353,7 +353,7 @@ compact_debug! {
                                 kinds.clone(),
                                 self.src_path.path().unwrap().to_path_buf(),
                                 self.edition,
-                            ).inner.clone(),
+                            ).inner,
                             format!("lib_target({:?}, {:?}, {:?}, {:?})",
                                     self.name, kinds, self.src_path, self.edition),
                         )
@@ -366,21 +366,21 @@ compact_debug! {
                                         &self.name,
                                         path.to_path_buf(),
                                         self.edition,
-                                    ).inner.clone(),
+                                    ).inner,
                                     format!("custom_build_target({:?}, {:?}, {:?})",
                                             self.name, path, self.edition),
                                 )
                             }
                             TargetSourcePath::Metabuild => {
                                 (
-                                    Target::metabuild_target(&self.name).inner.clone(),
+                                    Target::metabuild_target(&self.name).inner,
                                     format!("metabuild_target({:?})", self.name),
                                 )
                             }
                         }
                     }
                     _ => (
-                        Target::new(self.src_path.clone(), self.edition).inner.clone(),
+                        Target::new(self.src_path.clone(), self.edition).inner,
                         format!("with_path({:?}, {:?})", self.src_path, self.edition),
                     ),
                 }
diff --git a/src/cargo/ops/cargo_compile.rs b/src/cargo/ops/cargo_compile.rs
index 17d2a5ee121..31aaf361051 100644
--- a/src/cargo/ops/cargo_compile.rs
+++ b/src/cargo/ops/cargo_compile.rs
@@ -419,7 +419,7 @@ pub fn create_bcx<'a, 'cfg>(
         &resolved_features,
         &pkg_set,
         &profiles,
-        &interner,
+        interner,
     )?;
 
     let std_roots = if let Some(crates) = &config.cli_unstable().build_std {
@@ -442,7 +442,7 @@ pub fn create_bcx<'a, 'cfg>(
             std_features,
             build_config.requested_kind,
             &pkg_set,
-            &interner,
+            interner,
             &profiles,
         )?
     } else {
@@ -491,7 +491,7 @@ pub fn create_bcx<'a, 'cfg>(
         build_config.mode,
         &target_data,
         &profiles,
-        &interner,
+        interner,
     )?;
 
     let bcx = BuildContext::new(
diff --git a/src/cargo/ops/cargo_package.rs b/src/cargo/ops/cargo_package.rs
index 772c6f87f67..5dcdd2ff4ed 100644
--- a/src/cargo/ops/cargo_package.rs
+++ b/src/cargo/ops/cargo_package.rs
@@ -823,25 +823,12 @@ fn check_filename(file: &Path, shell: &mut Shell) -> CargoResult<()> {
             file.display()
         )
     }
-    let mut check_windows = |name| -> CargoResult<()> {
-        if restricted_names::is_windows_reserved(name) {
-            shell.warn(format!(
-                "file {} is a reserved Windows filename, \
+    if restricted_names::is_windows_reserved_path(file) {
+        shell.warn(format!(
+            "file {} is a reserved Windows filename, \
                 it will not work on Windows platforms",
-                file.display()
-            ))?;
-        }
-        Ok(())
-    };
-    for component in file.iter() {
-        if let Some(component) = component.to_str() {
-            check_windows(component)?;
-        }
-    }
-    if file.extension().is_some() {
-        if let Some(stem) = file.file_stem().and_then(|s| s.to_str()) {
-            check_windows(stem)?;
-        }
+            file.display()
+        ))?;
     }
     Ok(())
 }
diff --git a/src/cargo/ops/registry.rs b/src/cargo/ops/registry.rs
index 69e778f155d..9de9c41477f 100644
--- a/src/cargo/ops/registry.rs
+++ b/src/cargo/ops/registry.rs
@@ -811,7 +811,7 @@ fn get_source_id(
     reg: Option<&String>,
 ) -> CargoResult<SourceId> {
     match (reg, index) {
-        (Some(r), _) => SourceId::alt_registry(config, &r),
+        (Some(r), _) => SourceId::alt_registry(config, r),
         (_, Some(i)) => SourceId::for_registry(&i.into_url()?),
         _ => {
             let map = SourceConfigMap::new(config)?;
diff --git a/src/cargo/ops/resolve.rs b/src/cargo/ops/resolve.rs
index dd32b9367d6..220946ea2c1 100644
--- a/src/cargo/ops/resolve.rs
+++ b/src/cargo/ops/resolve.rs
@@ -127,7 +127,7 @@ pub fn resolve_ws_with_opts<'cfg>(
     let pkg_set = get_resolved_packages(&resolved_with_overrides, registry)?;
 
     let member_ids = ws
-        .members_with_features(&specs, &opts.features)?
+        .members_with_features(specs, &opts.features)?
         .into_iter()
         .map(|(p, _fts)| p.package_id())
         .collect::<Vec<_>>();
@@ -136,7 +136,7 @@ pub fn resolve_ws_with_opts<'cfg>(
         &member_ids,
         has_dev_units,
         requested_target,
-        &target_data,
+        target_data,
     )?;
 
     let resolved_features = FeatureResolver::resolve(
diff --git a/src/cargo/sources/registry/mod.rs b/src/cargo/sources/registry/mod.rs
index 9a181b9077f..4c340026cbf 100644
--- a/src/cargo/sources/registry/mod.rs
+++ b/src/cargo/sources/registry/mod.rs
@@ -178,7 +178,7 @@ use crate::sources::PathSource;
 use crate::util::errors::CargoResultExt;
 use crate::util::hex;
 use crate::util::into_url::IntoUrl;
-use crate::util::{CargoResult, Config, Filesystem};
+use crate::util::{restricted_names, CargoResult, Config, Filesystem};
 
 const PACKAGE_SOURCE_LOCK: &str = ".cargo-ok";
 pub const CRATES_IO_INDEX: &str = "https://github.com/rust-lang/crates.io-index";
@@ -495,11 +495,18 @@ impl<'cfg> RegistrySource<'cfg> {
                     prefix
                 )
             }
-
-            // Once that's verified, unpack the entry as usual.
-            entry
-                .unpack_in(parent)
-                .chain_err(|| format!("failed to unpack entry at `{}`", entry_path.display()))?;
+            // Unpacking failed
+            let mut result = entry.unpack_in(parent).map_err(anyhow::Error::from);
+            if cfg!(windows) && restricted_names::is_windows_reserved_path(&entry_path) {
+                result = result.chain_err(|| {
+                    format!(
+                        "`{}` appears to contain a reserved Windows path, \
+                        it cannot be extracted on Windows",
+                        entry_path.display()
+                    )
+                });
+            }
+            result.chain_err(|| format!("failed to unpack entry at `{}`", entry_path.display()))?;
         }
 
         // Write to the lock file to indicate that unpacking was successful.
diff --git a/src/cargo/util/restricted_names.rs b/src/cargo/util/restricted_names.rs
index ad9df7dc122..3e1cb036de8 100644
--- a/src/cargo/util/restricted_names.rs
+++ b/src/cargo/util/restricted_names.rs
@@ -2,6 +2,7 @@
 
 use crate::util::CargoResult;
 use anyhow::bail;
+use std::path::Path;
 
 /// Returns `true` if the name contains non-ASCII characters.
 pub fn is_non_ascii_name(name: &str) -> bool {
@@ -81,3 +82,13 @@ pub fn validate_package_name(name: &str, what: &str, help: &str) -> CargoResult<
     }
     Ok(())
 }
+
+// Check the entire path for names reserved in Windows.
+pub fn is_windows_reserved_path(path: &Path) -> bool {
+    path.iter()
+        .filter_map(|component| component.to_str())
+        .any(|component| {
+            let stem = component.split('.').next().unwrap();
+            is_windows_reserved(stem)
+        })
+}
diff --git a/src/doc/src/reference/external-tools.md b/src/doc/src/reference/external-tools.md
index 410db2440b1..26f99fd0b3b 100644
--- a/src/doc/src/reference/external-tools.md
+++ b/src/doc/src/reference/external-tools.md
@@ -48,7 +48,11 @@ alter the way the JSON messages are computed and rendered. See the description
 of the `--message-format` option in the [build command documentation] for more
 details.
 
+If you are using Rust, the [cargo_metadata] crate can be used to parse these
+messages.
+
 [build command documentation]: ../commands/cargo-build.md
+[cargo_metadata]: https://crates.io/crates/cargo_metadata
 
 #### Compiler messages
 
diff --git a/tests/testsuite/package.rs b/tests/testsuite/package.rs
index ddfeea58d9f..c04b7786d46 100644
--- a/tests/testsuite/package.rs
+++ b/tests/testsuite/package.rs
@@ -1744,3 +1744,55 @@ src/lib.rs
         )
         .run();
 }
+
+#[cargo_test]
+#[cfg(windows)]
+fn reserved_windows_name() {
+    Package::new("bar", "1.0.0")
+        .file("src/lib.rs", "pub mod aux;")
+        .file("src/aux.rs", "")
+        .publish();
+
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+            [project]
+            name = "foo"
+            version = "0.0.1"
+            authors = []
+            license = "MIT"
+            description = "foo"
+
+            [dependencies]
+            bar = "1.0.0"
+        "#,
+        )
+        .file("src/main.rs", "extern crate bar;\nfn main() {  }")
+        .build();
+    p.cargo("package")
+        .with_status(101)
+        .with_stderr_contains(
+            "\
+error: failed to verify package tarball
+
+Caused by:
+  failed to download replaced source registry `[..]`
+
+Caused by:
+  failed to unpack package `[..] `[..]`)`
+
+Caused by:
+  failed to unpack entry at `[..]aux.rs`
+
+Caused by:
+  `[..]aux.rs` appears to contain a reserved Windows path, it cannot be extracted on Windows
+
+Caused by:
+  failed to unpack `[..]aux.rs`
+
+Caused by:
+  failed to unpack `[..]aux.rs` into `[..]aux.rs`",
+        )
+        .run();
+}