From ee5975319b149007a0100f15cc3356d352fb5b1c Mon Sep 17 00:00:00 2001
From: xbreak <xbreak@alphaware.se>
Date: Mon, 11 May 2020 18:34:11 +0000
Subject: [PATCH] qt5: Add missing include path to pkg-config files

This is achieved by patching qtbase `qmake/generators/makefile.cpp` to
unconditionally add the missing `-I${includedir}`. The include path is
otherwise conditioned on whether it is already available or not. Since there is
no unified set of system include paths in nix this cause problems as reported
in #52457.
---
 pkgs/development/libraries/qt-5/5.12/default.nix   |  5 +++++
 .../qtbase.patch.d/0014-qtbase-pkg-config.patch    | 14 ++++++++++++++
 2 files changed, 19 insertions(+)
 create mode 100644 pkgs/development/libraries/qt-5/5.12/qtbase.patch.d/0014-qtbase-pkg-config.patch

diff --git a/pkgs/development/libraries/qt-5/5.12/default.nix b/pkgs/development/libraries/qt-5/5.12/default.nix
index 78d711e969b5..3123e83960e8 100644
--- a/pkgs/development/libraries/qt-5/5.12/default.nix
+++ b/pkgs/development/libraries/qt-5/5.12/default.nix
@@ -67,6 +67,11 @@ let
         ./qtbase.patch.d/0010-qtbase-qtpluginpath.patch
         ./qtbase.patch.d/0011-qtbase-assert.patch
         ./qtbase.patch.d/0012-fix-header_module.patch
+
+        # Ensure -I${includedir} is added to Cflags in pkg-config files.
+        # See https://github.com/NixOS/nixpkgs/issues/52457
+        ./qtbase.patch.d/0014-qtbase-pkg-config.patch
+
         # https://bugreports.qt.io/browse/QTBUG-81715
         # remove after updating to qt > 5.12.7
         (fetchpatch {
diff --git a/pkgs/development/libraries/qt-5/5.12/qtbase.patch.d/0014-qtbase-pkg-config.patch b/pkgs/development/libraries/qt-5/5.12/qtbase.patch.d/0014-qtbase-pkg-config.patch
new file mode 100644
index 000000000000..90caaea1cf4d
--- /dev/null
+++ b/pkgs/development/libraries/qt-5/5.12/qtbase.patch.d/0014-qtbase-pkg-config.patch
@@ -0,0 +1,14 @@
+diff --git a/qmake/generators/makefile.cpp b/qmake/generators/makefile.cpp
+--- a/qmake/generators/makefile.cpp
++++ b/qmake/generators/makefile.cpp
+@@ -3390,8 +3390,7 @@ MakefileGenerator::writePkgConfigFile()
+       << varGlue("QMAKE_PKGCONFIG_CFLAGS", "", " ", " ")
+         //      << varGlue("DEFINES","-D"," -D"," ")
+          ;
+-    if (!project->values("QMAKE_DEFAULT_INCDIRS").contains(includeDir))
+-        t << "-I${includedir}";
++    t << "-I${includedir}";
+     if (target_mode == TARG_MAC_MODE && project->isActiveConfig("lib_bundle")
+         && libDir != QLatin1String("/Library/Frameworks")) {
+             t << " -F${libdir}";
+