From a61e4dbb180c7dabcc932ac03fc6d4d724b9178e Mon Sep 17 00:00:00 2001
From: David McFarland <corngood@gmail.com>
Date: Mon, 29 Dec 2025 14:53:21 -0400
Subject: [PATCH 01/11] cygwin-dll-link: move from make-derivation to cross
 stdenv

---
 .../cygwin/cygwin-dll-link-hook}/cygwin-dll-link.sh |  2 +-
 .../cygwin/cygwin-dll-link-hook/default.nix         | 13 +++++++++++++
 pkgs/os-specific/cygwin/default.nix                 |  2 ++
 pkgs/stdenv/cross/default.nix                       |  5 ++++-
 pkgs/stdenv/generic/make-derivation.nix             |  1 -
 5 files changed, 20 insertions(+), 3 deletions(-)
 rename pkgs/{build-support/setup-hooks => os-specific/cygwin/cygwin-dll-link-hook}/cygwin-dll-link.sh (98%)
 create mode 100644 pkgs/os-specific/cygwin/cygwin-dll-link-hook/default.nix

diff --git a/pkgs/build-support/setup-hooks/cygwin-dll-link.sh b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
similarity index 98%
rename from pkgs/build-support/setup-hooks/cygwin-dll-link.sh
rename to pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
index a9309925e658..371ba633edc8 100644
--- a/pkgs/build-support/setup-hooks/cygwin-dll-link.sh
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
@@ -18,7 +18,7 @@ addOutputDLLPaths() {
 postInstallHooks+=(addOutputDLLPaths)
 
 _dllDeps() {
-  "$OBJDUMP" -p "$1" \
+  @objdump@ -p "$1" \
     | sed -n 's/.*DLL Name: \(.*\)/\1/p' \
     | sort -u
 }
diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/default.nix b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/default.nix
new file mode 100644
index 000000000000..b3185140f2ea
--- /dev/null
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/default.nix
@@ -0,0 +1,13 @@
+{
+  lib,
+  makeSetupHook,
+  binutils-unwrapped,
+  stdenv,
+  callPackage,
+}:
+makeSetupHook {
+  name = "cygwin-dll-link-hook";
+  substitutions = {
+    objdump = "${lib.getBin binutils-unwrapped}/${stdenv.targetPlatform.config}/bin/objdump";
+  };
+} ./cygwin-dll-link.sh
diff --git a/pkgs/os-specific/cygwin/default.nix b/pkgs/os-specific/cygwin/default.nix
index 09f69ff9f9b2..d1217f7880c1 100644
--- a/pkgs/os-specific/cygwin/default.nix
+++ b/pkgs/os-specific/cygwin/default.nix
@@ -21,5 +21,7 @@ makeScopeWithSplicing' {
       # this is here to avoid symlinks being made to cygwin1.dll in /nix/store
       newlib-cygwin-nobin = callPackage ./newlib-cygwin/nobin.nix { };
       newlib-cygwin-headers = callPackage ./newlib-cygwin { headersOnly = true; };
+
+      cygwinDllLinkHook = callPackage ./cygwin-dll-link-hook { };
     };
 }
diff --git a/pkgs/stdenv/cross/default.nix b/pkgs/stdenv/cross/default.nix
index cc53957eee0d..b194c780a319 100644
--- a/pkgs/stdenv/cross/default.nix
+++ b/pkgs/stdenv/cross/default.nix
@@ -83,7 +83,10 @@ lib.init bootStages
                   || p.isGenode;
               in
               f hostPlatform && !(f buildPlatform)
-            ) buildPackages.updateAutotoolsGnuConfigScriptsHook;
+            ) buildPackages.updateAutotoolsGnuConfigScriptsHook
+            ++ lib.optional (
+              hostPlatform.isCygwin && !buildPlatform.isCygwin
+            ) buildPackages.cygwin.cygwinDllLinkHook;
         })
       );
     in
diff --git a/pkgs/stdenv/generic/make-derivation.nix b/pkgs/stdenv/generic/make-derivation.nix
index cdfeb34a2411..d66fbf71035e 100644
--- a/pkgs/stdenv/generic/make-derivation.nix
+++ b/pkgs/stdenv/generic/make-derivation.nix
@@ -475,7 +475,6 @@ let
           nativeBuildInputs
           ++ optional separateDebugInfo' ../../build-support/setup-hooks/separate-debug-info.sh
           ++ optional isWindows ../../build-support/setup-hooks/win-dll-link.sh
-          ++ optional isCygwin ../../build-support/setup-hooks/cygwin-dll-link.sh
           ++ optionals doCheck nativeCheckInputs
           ++ optionals doInstallCheck nativeInstallCheckInputs;
 

From c345cee8a133e44e881225f57ad3d8eecdcb9644 Mon Sep 17 00:00:00 2001
From: David McFarland <corngood@gmail.com>
Date: Fri, 10 Oct 2025 13:17:27 -0300
Subject: [PATCH 02/11] cygwin-dll-link: use link for cygwin1.dll

---
 .../cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh          | 6 +++++-
 pkgs/stdenv/generic/make-derivation.nix                     | 1 -
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
index 371ba633edc8..2d2023d49a71 100644
--- a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
@@ -29,7 +29,11 @@ _linkDeps() {
   local dll
   _dllDeps "$target" | while read -r dll; do
     echo '  dll:' "$dll"
-    if [[ -e "$dir/$dll" ]]; then continue; fi
+    if [[ -L "$dir/$dll" || -e "$dir/$dll" ]]; then continue; fi
+    if [[ $dll = cygwin1.dll ]]; then
+      CYGWIN+=\ winsymlinks:nativestrict ln -sr /bin/cygwin1.dll "$dir"
+      continue
+    fi
     # Locate the DLL - it should be an *executable* file on $LINK_DLL_FOLDERS.
     local dllPath
     if ! dllPath="$(PATH="$(dirname "$target"):$LINK_DLL_FOLDERS" type -P "$dll")"; then
diff --git a/pkgs/stdenv/generic/make-derivation.nix b/pkgs/stdenv/generic/make-derivation.nix
index d66fbf71035e..4f5ee160dbcf 100644
--- a/pkgs/stdenv/generic/make-derivation.nix
+++ b/pkgs/stdenv/generic/make-derivation.nix
@@ -704,7 +704,6 @@ let
               allowedImpureDLLs
               ++ lib.optionals isCygwin [
                 "KERNEL32.dll"
-                "cygwin1.dll"
               ];
           }
           // (

From ae16ae18f5f6faee70de642adf10ea2cf59efe40 Mon Sep 17 00:00:00 2001
From: David McFarland <corngood@gmail.com>
Date: Tue, 21 Oct 2025 13:55:40 -0300
Subject: [PATCH 03/11] cygwin-dll-link: skip non-executable files

---
 pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
index 2d2023d49a71..49cbde49174c 100644
--- a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
@@ -25,6 +25,7 @@ _dllDeps() {
 
 _linkDeps() {
   local target="$1" dir="$2" check="$3"
+  [[ ! -x "$target" ]] && echo "_linkDeps: $target is not executable, skipping." 1>&2 && return
   echo 'target:' "$target"
   local dll
   _dllDeps "$target" | while read -r dll; do

From 0beb3436f0156f57fe3e892d7f900b098e2e1981 Mon Sep 17 00:00:00 2001
From: David McFarland <corngood@gmail.com>
Date: Tue, 21 Oct 2025 14:15:44 -0300
Subject: [PATCH 04/11] cygwin-dll-link: include /lib/ when searching for PEs

---
 pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
index 49cbde49174c..2fddfc349b94 100644
--- a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
@@ -72,7 +72,7 @@ linkDLLs() {
 
     # Iterate over any DLL that we depend on.
     local target
-    for target in {bin,libexec}/**/*.{exe,dll}; do
+    for target in {bin,lib,libexec}/**/*.{exe,dll}; do
       [[ ! -f "$target" || ! -x "$target" ]] ||
         _linkDeps "$target" "$(dirname "$target")" "1"
     done

From f42d59445bf3fa8b37c1203158e0ba48dec84761 Mon Sep 17 00:00:00 2001
From: David McFarland <corngood@gmail.com>
Date: Tue, 21 Oct 2025 20:59:52 -0300
Subject: [PATCH 05/11] cygwin-dll-link: move DLLs to $lib/bin by default

This allows us to remove LINK_DLL_FOLDERS and use HOST_PATH instead.
---
 pkgs/build-support/cc-wrapper/default.nix     |  2 +-
 .../cygwin-dll-link-hook/cygwin-dll-link.sh   | 21 +++++++++----------
 2 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/pkgs/build-support/cc-wrapper/default.nix b/pkgs/build-support/cc-wrapper/default.nix
index 9bb07456e8f2..058b2d7a2dec 100644
--- a/pkgs/build-support/cc-wrapper/default.nix
+++ b/pkgs/build-support/cc-wrapper/default.nix
@@ -603,7 +603,7 @@ stdenvNoCC.mkDerivation {
       installPhase =
         if targetPlatform.isCygwin then
           ''
-            echo addToSearchPath "LINK_DLL_FOLDERS" "${cc_bin}/lib" >> $out
+            echo addToSearchPath "HOST_PATH" "${cc_bin}/lib" >> $out
             # Work around build failure caused by the gnulib workaround for
             # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114870. remove after
             # gnulib is updated in core packages (e.g. iconv, gnupatch, gnugrep)
diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
index 2fddfc349b94..6fe69347861e 100644
--- a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
@@ -1,21 +1,20 @@
 # shellcheck shell=bash
 
-addLinkDLLPaths() {
-  addToSearchPath "LINK_DLL_FOLDERS" "$1/lib"
-  addToSearchPath "LINK_DLL_FOLDERS" "$1/bin"
+_moveDLLsToLib() {
+  if [[ "${dontMoveDLLsToLib-}" ]]; then return; fi
+  # shellcheck disable=SC2154
+  moveToOutput "bin/*.dll" "${!outputLib}"
 }
 
-# shellcheck disable=SC2154
-addEnvHooks "$targetOffset" addLinkDLLPaths
+preFixupHooks+=(_moveDLLsToLib)
 
 addOutputDLLPaths() {
   for output in $(getAllOutputNames); do
-    addToSearchPath "LINK_DLL_FOLDERS" "${!output}/lib"
-    addToSearchPath "LINK_DLL_FOLDERS" "${!output}/bin"
+    addToSearchPath "HOST_PATH" "${!output}/bin"
   done
 }
 
-postInstallHooks+=(addOutputDLLPaths)
+preFixupHooks+=(addOutputDLLPaths)
 
 _dllDeps() {
   @objdump@ -p "$1" \
@@ -35,13 +34,13 @@ _linkDeps() {
       CYGWIN+=\ winsymlinks:nativestrict ln -sr /bin/cygwin1.dll "$dir"
       continue
     fi
-    # Locate the DLL - it should be an *executable* file on $LINK_DLL_FOLDERS.
+    # Locate the DLL - it should be an *executable* file on $HOST_PATH.
     local dllPath
-    if ! dllPath="$(PATH="$(dirname "$target"):$LINK_DLL_FOLDERS" type -P "$dll")"; then
+    if ! dllPath="$(PATH="$(dirname "$target"):$HOST_PATH" type -P "$dll")"; then
       if [[ -z "$check" || -n "${allowedImpureDLLsMap[$dll]}" ]]; then
         continue
       fi
-      echo unable to find "$dll" in "$LINK_DLL_FOLDERS" >&2
+      echo unable to find "$dll" in "$HOST_PATH" >&2
       exit 1
     fi
     echo '    linking to:' "$dllPath"

From f2ac4eef529fc8235167790f786859f048040c23 Mon Sep 17 00:00:00 2001
From: David McFarland <corngood@gmail.com>
Date: Sun, 8 Feb 2026 18:34:46 -0400
Subject: [PATCH 06/11] gcc: move cygwin DLLs to $target/bin

---
 pkgs/build-support/cc-wrapper/default.nix         | 2 +-
 pkgs/development/compilers/gcc/common/builder.nix | 7 +++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/pkgs/build-support/cc-wrapper/default.nix b/pkgs/build-support/cc-wrapper/default.nix
index 058b2d7a2dec..89cc7c4ce4fd 100644
--- a/pkgs/build-support/cc-wrapper/default.nix
+++ b/pkgs/build-support/cc-wrapper/default.nix
@@ -603,7 +603,7 @@ stdenvNoCC.mkDerivation {
       installPhase =
         if targetPlatform.isCygwin then
           ''
-            echo addToSearchPath "HOST_PATH" "${cc_bin}/lib" >> $out
+            echo addToSearchPath "HOST_PATH" "${cc_solib}/bin" >> $out
             # Work around build failure caused by the gnulib workaround for
             # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114870. remove after
             # gnulib is updated in core packages (e.g. iconv, gnupatch, gnugrep)
diff --git a/pkgs/development/compilers/gcc/common/builder.nix b/pkgs/development/compilers/gcc/common/builder.nix
index b1b5daeb00f1..1e90828a6643 100644
--- a/pkgs/development/compilers/gcc/common/builder.nix
+++ b/pkgs/development/compilers/gcc/common/builder.nix
@@ -363,6 +363,13 @@ originalAttrs:
           fi
       done
     ''
+    + lib.optionalString stdenv.targetPlatform.isCygwin ''
+      targetBinDir="''${targetConfig+$targetConfig/}bin"
+      for i in "''${!outputBin}/$targetLibDir"/cyg*.dll; do
+        mkdir -p "''${!outputLib}/$targetBinDir"
+        mv "$i" "''${!outputLib}/$targetBinDir"/
+      done
+    ''
     # if cross-compiling, link from $lib/lib to $lib/${targetConfig}.
     # since native-compiles have $lib/lib as a directory (not a
     # symlink), this ensures that in every case we can assume that

From f5353dd50e51524cb3367010647e70662991343f Mon Sep 17 00:00:00 2001
From: David McFarland <corngood@gmail.com>
Date: Sun, 8 Feb 2026 18:51:59 -0400
Subject: [PATCH 07/11] cygwin-dll-link: improve search path order

The search order will now be:

1. link target path
2. output bin paths
3. explicit input paths (e.g. libc)
4. HOST_PATH
---
 pkgs/build-support/cc-wrapper/default.nix         |  2 +-
 .../cygwin-dll-link-hook/cygwin-dll-link.sh       | 15 +++++++++------
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/pkgs/build-support/cc-wrapper/default.nix b/pkgs/build-support/cc-wrapper/default.nix
index 89cc7c4ce4fd..808fe5db2780 100644
--- a/pkgs/build-support/cc-wrapper/default.nix
+++ b/pkgs/build-support/cc-wrapper/default.nix
@@ -603,7 +603,7 @@ stdenvNoCC.mkDerivation {
       installPhase =
         if targetPlatform.isCygwin then
           ''
-            echo addToSearchPath "HOST_PATH" "${cc_solib}/bin" >> $out
+            echo addToSearchPath "_linkDeps_inputPath" "${cc_solib}/bin" >> $out
             # Work around build failure caused by the gnulib workaround for
             # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114870. remove after
             # gnulib is updated in core packages (e.g. iconv, gnupatch, gnugrep)
diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
index 6fe69347861e..3711ef494ed1 100644
--- a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
@@ -8,13 +8,15 @@ _moveDLLsToLib() {
 
 preFixupHooks+=(_moveDLLsToLib)
 
-addOutputDLLPaths() {
+declare _linkDeps_inputPath _linkDeps_outputPath
+
+_addOutputDLLPaths() {
   for output in $(getAllOutputNames); do
-    addToSearchPath "HOST_PATH" "${!output}/bin"
+    addToSearchPath _linkDeps_outputPath "${!output}/bin"
   done
 }
 
-preFixupHooks+=(addOutputDLLPaths)
+preFixupHooks+=(_addOutputDLLPaths)
 
 _dllDeps() {
   @objdump@ -p "$1" \
@@ -35,12 +37,13 @@ _linkDeps() {
       continue
     fi
     # Locate the DLL - it should be an *executable* file on $HOST_PATH.
-    local dllPath
-    if ! dllPath="$(PATH="$(dirname "$target"):$HOST_PATH" type -P "$dll")"; then
+    local dllPath searchPath
+    searchPath=$(dirname "$target"):$_linkDeps_outputPath:$_linkDeps_inputPath:$HOST_PATH
+    if ! dllPath="$(PATH="$searchPath" type -P "$dll")"; then
       if [[ -z "$check" || -n "${allowedImpureDLLsMap[$dll]}" ]]; then
         continue
       fi
-      echo unable to find "$dll" in "$HOST_PATH" >&2
+      echo unable to find "$dll" in "$searchPath" >&2
       exit 1
     fi
     echo '    linking to:' "$dllPath"

From cbb96285de25e950fa9cc63f797cfd08202aea1a Mon Sep 17 00:00:00 2001
From: David McFarland <corngood@gmail.com>
Date: Tue, 21 Oct 2025 14:15:21 -0300
Subject: [PATCH 08/11] cygwin-dll-link: allow linkDLLs to be used on
 individual dirs/files

---
 .../cygwin-dll-link-hook/cygwin-dll-link.sh   | 104 +++++++++++++-----
 1 file changed, 75 insertions(+), 29 deletions(-)

diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
index 3711ef494ed1..f5d1ae8e0a9c 100644
--- a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
@@ -24,39 +24,74 @@ _dllDeps() {
     | sort -u
 }
 
+declare -Ag _linkDeps_visited
+
 _linkDeps() {
-  local target="$1" dir="$2" check="$3"
-  [[ ! -x "$target" ]] && echo "_linkDeps: $target is not executable, skipping." 1>&2 && return
+  local target="$1" dir="$2"
+  if [[ -v _linkDeps_visited[$target] ]]; then
+    echo "_linkDeps: $target was already linked." 1>&2
+    return
+  fi
+  if [[ ! -f "$target" || ! -x "$target" ]]; then
+    echo "_linkDeps: $target is not an executable file, skipping." 1>&2
+    return
+  fi
+
+  local realTarget output inOutput
+  realTarget="$(readlink -f "$target")"
+  for output in $outputs ; do
+    if [[ $realTarget == "${!output}"* ]]; then
+      echo "_linkDeps: $target ($realTarget) is in $output (${!output})." 1>&2
+      inOutput=1
+      break
+    fi
+  done
+
   echo 'target:' "$target"
   local dll
-  _dllDeps "$target" | while read -r dll; do
+  while read -r dll; do
     echo '  dll:' "$dll"
-    if [[ -L "$dir/$dll" || -e "$dir/$dll" ]]; then continue; fi
-    if [[ $dll = cygwin1.dll ]]; then
-      CYGWIN+=\ winsymlinks:nativestrict ln -sr /bin/cygwin1.dll "$dir"
+    if [[ -v _linkDeps_visited[$dir/$dll] ]]; then
+      echo "_linkDeps: $dll was already linked into $dir." 1>&2
       continue
     fi
-    # Locate the DLL - it should be an *executable* file on $HOST_PATH.
-    local dllPath searchPath
-    searchPath=$(dirname "$target"):$_linkDeps_outputPath:$_linkDeps_inputPath:$HOST_PATH
-    if ! dllPath="$(PATH="$searchPath" type -P "$dll")"; then
-      if [[ -z "$check" || -n "${allowedImpureDLLsMap[$dll]}" ]]; then
-        continue
+    if [[ -L "$dir/$dll" || -e "$dir/$dll" ]]; then
+      echo '    already exists'
+      _linkDeps "$dir/$dll" "$dir"
+    else
+      local dllPath
+      if [[ $dll = cygwin1.dll ]]; then
+        dllPath=/bin/cygwin1.dll
+      else
+        local searchPath
+        searchPath=$(dirname "$target"):$_linkDeps_outputPath:$_linkDeps_inputPath:$HOST_PATH
+        # Locate the DLL - it should be an *executable* file on $HOST_PATH.
+        # This intentionally doesn't use $dir because we want to prefer dependencies
+        # that are already linked next to the target.
+        if ! dllPath="$(PATH="$searchPath" type -P "$dll")"; then
+          if [[ -z "$inOutput" || -n "${allowedImpureDLLsMap[$dll]}" ]]; then
+            continue
+          fi
+          echo unable to find "$dll" in "$searchPath" >&2
+          exit 1
+        fi
       fi
-      echo unable to find "$dll" in "$searchPath" >&2
-      exit 1
+      echo '    linking to:' "$dllPath"
+      CYGWIN+=\ winsymlinks:nativestrict ln -sr "$dllPath" "$dir"
+      _linkDeps "$dllPath" "$dir"
     fi
-    echo '    linking to:' "$dllPath"
-    CYGWIN+=\ winsymlinks:nativestrict ln -sr "$dllPath" "$dir"
-    # That DLL might have its own (transitive) dependencies,
-    # so add also all DLLs from its directory to be sure.
-    _linkDeps "$dllPath" "$dir" ""
-  done
+    _linkDeps_visited[$dir/$dll]=1
+  done < <(_dllDeps "$target")
 }
 
+# linkDLLsDir can be used to override the destination path for links.  This is
+# useful if you're trying to link dependencies of libraries into the directory
+# containing an executable.
+#
+# Arguments can be a file or directory path. Directories are searched
+# recursively.
 linkDLLs() {
   # shellcheck disable=SC2154
-  if [ ! -d "$prefix" ]; then return; fi
   (
     set -e
     shopt -s globstar nullglob
@@ -70,15 +105,26 @@ linkDLLs() {
       allowedImpureDLLsMap[$dll]=1
     done
 
-    cd "$prefix"
-
-    # Iterate over any DLL that we depend on.
-    local target
-    for target in {bin,lib,libexec}/**/*.{exe,dll}; do
-      [[ ! -f "$target" || ! -x "$target" ]] ||
-        _linkDeps "$target" "$(dirname "$target")" "1"
+    local target file
+    for target in "$@"; do
+      # Iterate over any DLL that we depend on.
+      if [[ -f "$target" ]]; then
+        _linkDeps "$target" "${linkDLLsDir-$(dirname "$target")}"
+      elif [[ -d "$target" ]]; then
+        for file in "${target%/}"/**/*.{exe,dll}; do
+          _linkDeps "$file" "${linkDLLsDir-$(dirname "$file")}"
+        done
+      else
+        echo "linkDLLs: $target is not a file or directory, skipping." 1>&2
+      fi
     done
   )
 }
 
-fixupOutputHooks+=(linkDLLs)
+_linkDLLs() {
+  # shellcheck disable=SC2154
+  if [[ ! -d $prefix || ${dontLinkDLLs-} ]]; then return; fi
+  linkDLLs "$prefix"/{bin,lib,libexec}/
+}
+
+fixupOutputHooks+=(_linkDLLs)

From dcebaab6239280506ba1d54d1d22f3f2c8fb5579 Mon Sep 17 00:00:00 2001
From: David McFarland <corngood@gmail.com>
Date: Mon, 29 Dec 2025 14:53:21 -0400
Subject: [PATCH 09/11] cygwin-dll-link: improve symlink handling

---
 .../cygwin-dll-link-hook/cygwin-dll-link.sh   | 48 ++++++++++++-------
 1 file changed, 30 insertions(+), 18 deletions(-)

diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
index f5d1ae8e0a9c..006dc0408cd0 100644
--- a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
@@ -28,20 +28,24 @@ declare -Ag _linkDeps_visited
 
 _linkDeps() {
   local target="$1" dir="$2"
+
+  # canonicalise these for the dictionary
+  target=$(realpath -s "$target")
+  dir=$(realpath -s "$dir")
+
   if [[ -v _linkDeps_visited[$target] ]]; then
     echo "_linkDeps: $target was already linked." 1>&2
     return
   fi
-  if [[ ! -f "$target" || ! -x "$target" ]]; then
+  if [[ ! -f $target || ! -x $target ]]; then
     echo "_linkDeps: $target is not an executable file, skipping." 1>&2
     return
   fi
 
-  local realTarget output inOutput
-  realTarget="$(readlink -f "$target")"
+  local output inOutput
   for output in $outputs ; do
-    if [[ $realTarget == "${!output}"* ]]; then
-      echo "_linkDeps: $target ($realTarget) is in $output (${!output})." 1>&2
+    if [[ $target == "${!output}"* && ! -L $target ]]; then
+      echo "_linkDeps: $target is in $output (${!output})." 1>&2
       inOutput=1
       break
     fi
@@ -51,25 +55,32 @@ _linkDeps() {
   local dll
   while read -r dll; do
     echo '  dll:' "$dll"
-    if [[ -v _linkDeps_visited[$dir/$dll] ]]; then
+    local dllPath=$dir/$dll
+    if [[ -v _linkDeps_visited[$dllPath] ]]; then
       echo "_linkDeps: $dll was already linked into $dir." 1>&2
       continue
     fi
-    if [[ -L "$dir/$dll" || -e "$dir/$dll" ]]; then
-      echo '    already exists'
-      _linkDeps "$dir/$dll" "$dir"
+    if [[ -L $dllPath ]]; then
+      echo '    already linked'
+      dllPath=$(realpath -s "$(readlink "$dllPath")")
+      _linkDeps "$dllPath" "$dir"
+    elif [[ -e $dllPath ]]; then
+      echo '    already exits'
+      _linkDeps "$dllPath" "$dir"
     else
-      local dllPath
       if [[ $dll = cygwin1.dll ]]; then
         dllPath=/bin/cygwin1.dll
       else
-        local searchPath
-        searchPath=$(dirname "$target"):$_linkDeps_outputPath:$_linkDeps_inputPath:$HOST_PATH
-        # Locate the DLL - it should be an *executable* file on $HOST_PATH.
-        # This intentionally doesn't use $dir because we want to prefer dependencies
-        # that are already linked next to the target.
-        if ! dllPath="$(PATH="$searchPath" type -P "$dll")"; then
-          if [[ -z "$inOutput" || -n "${allowedImpureDLLsMap[$dll]}" ]]; then
+        # This intentionally doesn't use $dir because we want to prefer
+        # dependencies that are already linked next to the target.
+        local searchPath realTarget
+        searchPath=$_linkDeps_outputPath:$_linkDeps_inputPath:$HOST_PATH
+        if [[ -L $target ]]; then
+          searchPath=$searchPath:$(dirname "$(readlink "$target")")
+        fi
+        searchPath=$(dirname "$target"):$searchPath
+        if ! dllPath=$(PATH="$searchPath" type -P "$dll"); then
+          if [[ -z $inOutput || -n ${allowedImpureDLLsMap[$dll]} ]]; then
             continue
           fi
           echo unable to find "$dll" in "$searchPath" >&2
@@ -82,6 +93,7 @@ _linkDeps() {
     fi
     _linkDeps_visited[$dir/$dll]=1
   done < <(_dllDeps "$target")
+  wait $!
 }
 
 # linkDLLsDir can be used to override the destination path for links.  This is
@@ -94,7 +106,7 @@ linkDLLs() {
   # shellcheck disable=SC2154
   (
     set -e
-    shopt -s globstar nullglob
+    shopt -s globstar nullglob dotglob
 
     local -a allowedImpureDLLsArray
     concatTo allowedImpureDLLsArray allowedImpureDLLs

From f1d9560d4032c5df9c46fe57cb1e38d8b8f9fec3 Mon Sep 17 00:00:00 2001
From: David McFarland <corngood@gmail.com>
Date: Sun, 8 Feb 2026 19:40:32 -0400
Subject: [PATCH 10/11] cygwin.cygwinDllLinkHook: add tests

---
 .../cygwin/cygwin-dll-link-hook/default.nix   |   2 +
 .../cygwin-dll-link-hook/tests/default.nix    | 130 ++++++++++++++++++
 .../cygwin-dll-link-hook/tests/dll/Makefile   |  16 +++
 .../cygwin-dll-link-hook/tests/dll/hello.c    |   7 +
 .../cygwin-dll-link-hook/tests/dll/hello.h    |   2 +
 .../cygwin-dll-link-hook/tests/dll2/Makefile  |  16 +++
 .../cygwin-dll-link-hook/tests/dll2/hello2.c  |   6 +
 .../cygwin-dll-link-hook/tests/dll2/hello2.h  |   2 +
 .../cygwin-dll-link-hook/tests/exe/Makefile   |  13 ++
 .../cygwin-dll-link-hook/tests/exe/main.c     |   6 +
 .../tests/user32-dll/Makefile                 |  16 +++
 .../tests/user32-dll/peek.c                   |   7 +
 .../tests/user32-dll/peek.h                   |   2 +
 .../tests/user32-exe/Makefile                 |  13 ++
 .../tests/user32-exe/main.c                   |   6 +
 .../tests/user32/Makefile                     |  13 ++
 .../cygwin-dll-link-hook/tests/user32/main.c  |   7 +
 17 files changed, 264 insertions(+)
 create mode 100644 pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/default.nix
 create mode 100644 pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/dll/Makefile
 create mode 100644 pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/dll/hello.c
 create mode 100644 pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/dll/hello.h
 create mode 100644 pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/dll2/Makefile
 create mode 100644 pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/dll2/hello2.c
 create mode 100644 pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/dll2/hello2.h
 create mode 100644 pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/exe/Makefile
 create mode 100644 pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/exe/main.c
 create mode 100644 pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32-dll/Makefile
 create mode 100644 pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32-dll/peek.c
 create mode 100644 pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32-dll/peek.h
 create mode 100644 pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32-exe/Makefile
 create mode 100644 pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32-exe/main.c
 create mode 100644 pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32/Makefile
 create mode 100644 pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32/main.c

diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/default.nix b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/default.nix
index b3185140f2ea..ff9eed6bdeef 100644
--- a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/default.nix
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/default.nix
@@ -10,4 +10,6 @@ makeSetupHook {
   substitutions = {
     objdump = "${lib.getBin binutils-unwrapped}/${stdenv.targetPlatform.config}/bin/objdump";
   };
+
+  passthru.tests = callPackage ./tests { };
 } ./cygwin-dll-link.sh
diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/default.nix b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/default.nix
new file mode 100644
index 000000000000..a8744001dc2d
--- /dev/null
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/default.nix
@@ -0,0 +1,130 @@
+{
+  dieHook,
+  lib,
+  stdenv,
+  testers,
+  runCommand,
+}:
+
+rec {
+  dll = stdenv.mkDerivation {
+    name = "dll";
+    src = ./dll;
+    outputs = [
+      "out"
+      "dev"
+    ];
+    buildInputs = [ dll2 ];
+    strictDeps = true;
+  };
+
+  dll2 = stdenv.mkDerivation {
+    name = "dll2";
+    src = ./dll2;
+    outputs = [
+      "out"
+      "dev"
+    ];
+  };
+
+  exe = stdenv.mkDerivation {
+    name = "exe";
+    src = ./exe;
+    buildInputs = [ dll ];
+    nativeBuildInputs = [ dieHook ];
+    strictDeps = true;
+    doCheck = true;
+    postFixup = ''[[ -e "$out"/bin/cyghello2.dll ]] || die missing indirect dependency'';
+  };
+
+  link-dll = exe.overrideAttrs {
+    name = "link-dll";
+    preFixup = ''
+      ln -s ${lib.getLib dll}/bin/cyghello.dll "$out"/bin/
+    '';
+  };
+
+  user32 = stdenv.mkDerivation {
+    name = "user32";
+    src = ./user32;
+    allowedImpureDLLs = [ "USER32.dll" ];
+  };
+
+  impure-dll = testers.testBuildFailure (
+    user32.overrideAttrs {
+      name = "impure-dll";
+      allowedImpureDLLs = [ ];
+    }
+  );
+
+  user32-dll = stdenv.mkDerivation {
+    name = "user32-dll";
+    src = ./user32-dll;
+    outputs = [
+      "out"
+      "dev"
+    ];
+    allowedImpureDLLs = [ "USER32.dll" ];
+  };
+
+  user32-exe = stdenv.mkDerivation {
+    name = "user32-exe";
+    src = ./user32-exe;
+    buildInputs = [ user32-dll ];
+    strictDeps = true;
+    doCheck = true;
+  };
+
+  link-dir-dll = exe.overrideAttrs {
+    name = "link-dir-dll";
+    preFixup = ''
+      mkdir "$out"/libexec
+      ln -s ${lib.getLib user32-dll}/bin/cygpeek.dll "$out"/libexec/
+      linkDLLsDir="$out"/bin linkDLLs "$out"/libexec/cygpeek.dll
+    '';
+  };
+
+  link-dir-exe = exe.overrideAttrs {
+    name = "link-dir-exe";
+    preFixup = ''
+      mkdir "$out"/libexec
+      ln -s ${lib.getLib user32-exe}/bin/{peek.exe,cygpeek.dll} "$out"/libexec/
+      linkDLLsDir="$out"/bin linkDLLs "$out"/libexec/peek.exe
+    '';
+  };
+
+  link-user32-dll = exe.overrideAttrs {
+    name = "link-user32-dll";
+    preFixup = ''
+      ln -s ${lib.getLib user32-dll}/bin/cygpeek.dll "$out"/bin/
+    '';
+  };
+
+  copy-dll-impure = testers.testBuildFailure (
+    user32-exe.overrideAttrs {
+      name = "copy-dll-impure";
+      preFixup = ''
+        cp ${lib.getLib user32-dll}/bin/cygpeek.dll "$out"/bin/
+      '';
+    }
+  );
+
+  copy-dll = user32-exe.overrideAttrs {
+    name = "copy-dll";
+    preFixup = ''
+      cp ${lib.getLib user32-dll}/bin/cygpeek.dll "$out"/bin/
+      linkDLLs "$out"/bin/cygpeek.dll
+    '';
+    allowedImpureDLLs = [ "USER32.dll" ];
+  };
+
+  double-link = user32-exe.overrideAttrs {
+    name = "double-link";
+    preFixup = ''linkDLLs "$out"'';
+  };
+
+  utf8-glob = runCommand "utf8-glob" { } ''
+    touch NetLock_Arany_=Class_Gold=_Főtanstvny:49412ce40010.crt
+    ls -l NetLock* > "$out"
+  '';
+}
diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/dll/Makefile b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/dll/Makefile
new file mode 100644
index 000000000000..25e1e53c38e4
--- /dev/null
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/dll/Makefile
@@ -0,0 +1,16 @@
+.PHONY: all install
+all: cyghello.dll
+
+install: $(out)/bin/cyghello.dll $(out)/lib/libhello.dll.a $(out)/include/hello.h
+
+cyghello.dll libhello.dll.a: hello.c
+	$(CC) -o $@ $^ -shared -Wl,--out-implib,libhello.dll.a -Wl,--export-all-symbols -lhello2
+
+$(out)/bin/cyghello.dll: cyghello.dll
+	install -m755 -D $< $@
+
+$(out)/lib/libhello.dll.a: libhello.dll.a
+	install -m644 -D $< $@
+
+$(out)/include/hello.h: hello.h
+	install -m644 -D $< $@
diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/dll/hello.c b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/dll/hello.c
new file mode 100644
index 000000000000..db1a301c91a4
--- /dev/null
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/dll/hello.c
@@ -0,0 +1,7 @@
+#include "hello.h"
+#include <stdio.h>
+#include <hello2.h>
+
+void hello() {
+				hello2();
+}
diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/dll/hello.h b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/dll/hello.h
new file mode 100644
index 000000000000..a4a0b54c6052
--- /dev/null
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/dll/hello.h
@@ -0,0 +1,2 @@
+#pragma once
+void hello();
diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/dll2/Makefile b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/dll2/Makefile
new file mode 100644
index 000000000000..87c5c1a9b9cc
--- /dev/null
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/dll2/Makefile
@@ -0,0 +1,16 @@
+.PHONY: all install
+all: cyghello2.dll
+
+install: $(out)/bin/cyghello2.dll $(out)/lib/libhello2.dll.a $(out)/include/hello2.h
+
+cyghello2.dll libhello2.dll.a: hello2.c
+	$(CC) -o $@ $^ -shared -Wl,--out-implib,libhello2.dll.a -Wl,--export-all-symbols
+
+$(out)/bin/cyghello2.dll: cyghello2.dll
+	install -m755 -D $< $@
+
+$(out)/lib/libhello2.dll.a: libhello2.dll.a
+	install -m644 -D $< $@
+
+$(out)/include/hello2.h: hello2.h
+	install -m644 -D $< $@
diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/dll2/hello2.c b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/dll2/hello2.c
new file mode 100644
index 000000000000..d23050fbb776
--- /dev/null
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/dll2/hello2.c
@@ -0,0 +1,6 @@
+#include <stdio.h>
+#include "hello2.h"
+
+void hello2() {
+				printf("Hello, World!\n");
+}
diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/dll2/hello2.h b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/dll2/hello2.h
new file mode 100644
index 000000000000..34e200a07e95
--- /dev/null
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/dll2/hello2.h
@@ -0,0 +1,2 @@
+#pragma once
+void hello2();
diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/exe/Makefile b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/exe/Makefile
new file mode 100644
index 000000000000..da16b5d08c79
--- /dev/null
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/exe/Makefile
@@ -0,0 +1,13 @@
+.PHONY: all check install
+all: hello.exe
+
+install: $(out)/bin/hello.exe
+
+hello.exe: main.c
+	$(CC) -o $@ $^ -lhello
+
+check: hello.exe
+	./hello.exe
+
+$(out)/bin/hello.exe: hello.exe
+	install -m755 -D $< $@
diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/exe/main.c b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/exe/main.c
new file mode 100644
index 000000000000..9dbc882ea430
--- /dev/null
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/exe/main.c
@@ -0,0 +1,6 @@
+#include <hello.h>
+
+int main() {
+				hello();
+				return 0;
+}
diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32-dll/Makefile b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32-dll/Makefile
new file mode 100644
index 000000000000..483ad8854a06
--- /dev/null
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32-dll/Makefile
@@ -0,0 +1,16 @@
+.PHONY: all install
+all: cygpeek.dll
+
+install: $(out)/bin/cygpeek.dll $(out)/lib/libpeek.dll.a $(out)/include/peek.h
+
+cygpeek.dll libpeek.dll.a: peek.c
+	$(CC) -o $@ $^ -shared -Wl,--out-implib,libpeek.dll.a -Wl,--export-all-symbols
+
+$(out)/bin/cygpeek.dll: cygpeek.dll
+	install -m755 -D $< $@
+
+$(out)/lib/libpeek.dll.a: libpeek.dll.a
+	install -m644 -D $< $@
+
+$(out)/include/peek.h: peek.h
+	install -m644 -D $< $@
diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32-dll/peek.c b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32-dll/peek.c
new file mode 100644
index 000000000000..715adb003c15
--- /dev/null
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32-dll/peek.c
@@ -0,0 +1,7 @@
+#include <windows.h>
+
+int peek()
+{
+				MSG msg;
+				PeekMessage(&msg, NULL, 0, 0, PM_NOREMOVE);
+}
diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32-dll/peek.h b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32-dll/peek.h
new file mode 100644
index 000000000000..800f23f77da5
--- /dev/null
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32-dll/peek.h
@@ -0,0 +1,2 @@
+#pragma once
+void peek();
diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32-exe/Makefile b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32-exe/Makefile
new file mode 100644
index 000000000000..231601818914
--- /dev/null
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32-exe/Makefile
@@ -0,0 +1,13 @@
+.PHONY: all check install
+all: peek.exe
+
+install: $(out)/bin/peek.exe
+
+peek.exe: main.c
+	$(CC) -o $@ $^ -lpeek
+
+check: peek.exe
+	./peek.exe
+
+$(out)/bin/peek.exe: peek.exe
+	install -m755 -D $< $@
diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32-exe/main.c b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32-exe/main.c
new file mode 100644
index 000000000000..cddc78c91cab
--- /dev/null
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32-exe/main.c
@@ -0,0 +1,6 @@
+#include <peek.h>
+
+int main() {
+				peek();
+				return 0;
+}
diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32/Makefile b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32/Makefile
new file mode 100644
index 000000000000..6c696a2e8cd0
--- /dev/null
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32/Makefile
@@ -0,0 +1,13 @@
+.PHONY: all check install
+all: hello.exe
+
+install: $(out)/bin/hello.exe
+
+hello.exe: main.c
+	$(CC) -o $@ $^
+
+check: hello.exe
+	./hello.exe
+
+$(out)/bin/hello.exe: hello.exe
+	install -m755 -D $< $@
diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32/main.c b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32/main.c
new file mode 100644
index 000000000000..9cc135770d21
--- /dev/null
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/tests/user32/main.c
@@ -0,0 +1,7 @@
+#include <windows.h>
+
+int main()
+{
+				MSG msg;
+				PeekMessage(&msg, NULL, 0, 0, PM_NOREMOVE);
+}

From a934e8a9e5a701efa45279def48d7aa097fe2db8 Mon Sep 17 00:00:00 2001
From: David McFarland <corngood@gmail.com>
Date: Sun, 8 Feb 2026 19:51:57 -0400
Subject: [PATCH 11/11] cygwin-dll-link: replace escaped space with quoting

---
 pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
index 006dc0408cd0..95e63b5458ab 100644
--- a/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
+++ b/pkgs/os-specific/cygwin/cygwin-dll-link-hook/cygwin-dll-link.sh
@@ -88,7 +88,7 @@ _linkDeps() {
         fi
       fi
       echo '    linking to:' "$dllPath"
-      CYGWIN+=\ winsymlinks:nativestrict ln -sr "$dllPath" "$dir"
+      CYGWIN+=' winsymlinks:nativestrict' ln -sr "$dllPath" "$dir"
       _linkDeps "$dllPath" "$dir"
     fi
     _linkDeps_visited[$dir/$dll]=1