[Buildroot] [PATCH v5] icu: fix static linking by adding -lstdc++ to pkg-config

[Shubham Chakraborty <chakrabortyshubham66@gmail.com>]

The ICU library requires C++ standard library when linking statically.
Without this, applications using pkg-config --libs --static icu-uc
will fail to link with undefined reference errors to C++ symbols.

This patch extends the existing fix for static linking to also add
-lstdc++ to the Libs field in the pkg-config file when building
in static-only mode (ENABLE_SHARED is not set).

Signed-off-by: Shubham Chakraborty <chakrabortyshubham66@gmail.com>
---
 .../0003-fix-static-linking-with-icu-uc.patch | 20 +++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/package/icu/0003-fix-static-linking-with-icu-uc.patch b/package/icu/0003-fix-static-linking-with-icu-uc.patch
index 36a3d1f696..d74aca8088 100644
--- a/package/icu/0003-fix-static-linking-with-icu-uc.patch
+++ b/package/icu/0003-fix-static-linking-with-icu-uc.patch
@@ -13,14 +13,26 @@ http://autobuild.buildroot.net/results/210/2107f9dfb39eeb6559fb4271c7af8b39aef52
 
 Signed-off-by: Romain Naour <romain.naour@openwide.fr>
 ---
- source/Makefile.in | 2 +-
- 1 file changed, 1 insertion(+), 1 deletion(-)
+This patch currently addresses linking against stdc++ for shared-library
+builds. Add -lstdc++ to the static build flags also, to fix 'undefined
+reference' errors when linking programs like xmlcatalog (libxml2)
+with musl static toolchains.
+
+Upstream: Inactive-Upstream [Buildroot specific]
+Signed-off-by: Shubham Chakraborty <chakrabortyshubham66@gmail.com>
+---
+ source/Makefile.in | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
 
 diff -git icu.orig/source/Makefile.in icu/source/Makefile.in
 --- icu.orig/source/Makefile.in	2025-03-13 19:31:23.000000000 +0100
 +++ icu/source/Makefile.in	2025-09-22 08:56:36.791792784 +0200
-@@ -279,7 +279,7 @@
- 	@echo "Libs:" '-L$${libdir}' "${ICULIBS_UC}" "${ICULIBS_DT}" '$${baselibs}' >> $@
+@@ -276,10 +276,10 @@
+ 	@echo "Description: $(PACKAGE_ICU_DESCRIPTION): Common and Data libraries" >> $@
+ 	@echo "Name: $(PACKAGE)-uc" >> $@
+ ifeq ($(ENABLE_SHARED),)
+-	@echo "Libs:" '-L$${libdir}' "${ICULIBS_UC}" "${ICULIBS_DT}" '$${baselibs}' >> $@
++	@echo "Libs:" '-L$${libdir}' "${ICULIBS_UC}" "${ICULIBS_DT}" '$${baselibs}' -lstdc++ >> $@
  else
  	@echo "Libs:" '-L$${libdir}' "${ICULIBS_UC}" >> $@
 -	@echo "Libs.private:" "${ICULIBS_DT}" '$${baselibs}' >> $@
-- 
2.53.0

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