From 3c597ced16e1f3aa7bfe08609add0feaf5c8d90d Mon Sep 17 00:00:00 2001
From: Viktor Szakats <commit@vsz.me>
Date: Sun, 17 May 2026 14:04:49 +0200
Subject: [PATCH] cmake: fix three issues generating lib options in config
 files

- drop duplicate libs lists next to each other in `libcurl.pc`.
  Logic copied from libssh2.
  Fixing (seen in a local build):
  ```diff
  -Libs.private: -lssh2 -lz -lz -lldap -llber -lssl -lcrypto -lcrypto -lz -lbrotlidec -lbrotlicommon -lzstd -lnghttp2 -licucore -liconv -lpsl -lbacktrace
  +Libs.private: -lssh2 -lz -lldap -llber -lssl -lcrypto -lz -lbrotlidec -lbrotlicommon -lzstd -lnghttp2 -licucore -liconv -lpsl -lbacktrace
  ```
  Refs:
  https://github.com/libssh2/libssh2/commit/e1da7b2cb89063fc253bf94570c1ccfb3f1c2e81
  https://github.com/libssh2/libssh2/pull/1621
  https://github.com/libssh2/libssh2/commit/6464301820a9ca4a56c5f02717430bbd4150c7b2
  https://github.com/libssh2/libssh2/pull/1131

- handle `$<LINK_ONLY:NAMESPACE::NAME>` references.
  Fixing (seen in a local build using libssh2 v1.11.2-DEV):
  ```diff
  -Libs.private: -lssh2 -l$<LINK_ONLY:OpenSSL::Crypto> -lz -lldap -llber [...]
  +Libs.private: -lssh2 -lcrypto -lz -lldap -llber [...]
  ```

- fix `-l-pthread` sneaking into `libcurl.pc`.
  Fixing (seen with Android):
  ```diff
  -Libs.private:  -lz -l-pthread
  +Libs.private: -pthread -lz
  ```
  Refs:
  https://github.com/microsoft/vcpkg/blob/2b65c20fc66eda893aa15a15a453c3cf09500b19/ports/curl/dependencies.patch#L631-L634
  https://github.com/microsoft/vcpkg/commit/70b941a5d2443e79eeab62507acb41bd22201277#diff-7f2c3b2f93cd3478671a603cbd5ef818c7c403a11dc25e1d3539e9b03495a5d3
  Upstream-patch-by: Kai Pastor

Closes #21654
---
 CMake/Macros.cmake |  4 ++++
 CMakeLists.txt     | 14 ++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/CMake/Macros.cmake b/CMake/Macros.cmake
index 5e26c38469..f0968736b0 100644
--- a/CMake/Macros.cmake
+++ b/CMake/Macros.cmake
@@ -267,6 +267,10 @@ macro(curl_collect_target_link_options _target)
   get_target_property(_val ${_target} INTERFACE_LINK_LIBRARIES)
   if(_val)
     foreach(_lib IN LISTS _val)
+      # E.g. via libssh2: "$<LINK_ONLY:OpenSSL::Crypto>"
+      if(_lib MATCHES "LINK_ONLY:")
+        string(REGEX MATCH "([A-Za-z0-9_-]+::[A-Za-z0-9_-]+)" _lib "${_lib}")  # Extract imported target name
+      endif()
       if(TARGET "${_lib}")
         curl_collect_target_link_options(${_lib})
       else()
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1c4c137add..331c22dc4f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2211,6 +2211,9 @@ if(NOT CURL_DISABLE_INSTALL)
             list(APPEND LIBCURL_PC_LIBS_PRIVATE "${_lib}")
             list(APPEND LIBCURL_PC_LIBS_PRIVATE_LIST "${_lib}")
           endif()
+        elseif(_lib MATCHES "^-")  # '-option'
+          list(APPEND _ldflags "${_lib}")
+          list(APPEND LIBCURL_PC_LIBS_PRIVATE_LIST "${_lib}")
         else()
           list(APPEND LIBCURL_PC_LIBS_PRIVATE "-l${_lib}")
           list(APPEND LIBCURL_PC_LIBS_PRIVATE_LIST "${_lib}")
@@ -2241,6 +2244,17 @@ if(NOT CURL_DISABLE_INSTALL)
     string(REPLACE ";" "," LIBCURL_PC_REQUIRES_PRIVATE "${LIBCURL_PC_REQUIRES_PRIVATE}")
   endif()
   if(LIBCURL_PC_LIBS_PRIVATE)
+    # Remove duplicates listed next to each other
+    set(_libs "")
+    set(_prev "")
+    foreach(_lib IN LISTS LIBCURL_PC_LIBS_PRIVATE)
+      if(NOT _prev STREQUAL _lib)
+        list(APPEND _libs "${_lib}")
+        set(_prev "${_lib}")
+      endif()
+    endforeach()
+    set(LIBCURL_PC_LIBS_PRIVATE "${_libs}")
+
     string(REPLACE ";" " " LIBCURL_PC_LIBS_PRIVATE "${LIBCURL_PC_LIBS_PRIVATE}")
   endif()
   if(_ldflags)