[Buildroot] [PATCH v2] package/qt5base: fix building with correct optimization

[Giulio Benetti]

In Qt5 mkspecs/features/default_post.prf(included after our qmake.conf):
debug {
    QMAKE_CFLAGS += $$QMAKE_CFLAGS_DEBUG
    QMAKE_CXXFLAGS += $$QMAKE_CXXFLAGS_DEBUG
    QMAKE_LFLAGS += $$QMAKE_LFLAGS_DEBUG
    QMAKE_LIBFLAGS += $$QMAKE_LIBFLAGS_DEBUG
} else {
    QMAKE_CFLAGS += $$QMAKE_CFLAGS_RELEASE
    QMAKE_CXXFLAGS += $$QMAKE_CXXFLAGS_RELEASE
    QMAKE_LFLAGS += $$QMAKE_LFLAGS_RELEASE
    QMAKE_LIBFLAGS += $$QMAKE_LIBFLAGS_RELEASE
}
QMAKE_CFLAGS is set to QMAKE_CFLAGS_RELEASE that in order is set to one
of QMAKE_CFLAGS_OPTIMIZE depending on qt5 optimization chosen.
Unfortunately patch:
https://git.buildroot.net/buildroot/commit/?id=7c0aa83527e0b0179f9e3f73a3e63df1fdc5a6e6
is not enough, since QMAKE_CFLAGS_RELEASE is set to
QMAKE_CFLAGS_OPTIMIZE in a unique file, resulting in resetting
QMAKE_CFLAGS_OPTIMIZE only after QMAKE_FLAGS_RELEASE is set.

The only way is to directly reset:
QMAKE_CFLAGS_RELEASE
QMAKE_CFLAGS_DEBUG
QMAKE_CXXFLAGS_RELEASE
QMAKE_CXXFLAGS_DEBUG
in our qmake.conf.in.

This package is also affected by BR2_TOOLCHAIN_HAS_GCC_BUG_90620 and
it's been worked around by appending -O0 to CFLAGS/CXXFLAGS. This bug
prevented workaround to work overriding optimization flags, so solving
this also solves workaround problem.

Fixes:
http://autobuild.buildroot.net/results/ada/adaa9b4bcc6f9d2b5e82c479859a07e8abf5cf13/
http://autobuild.buildroot.net/results/a83/a83bdd1f3bf309c07abebe871b017c331ed36e67/

Signed-off-by: Giulio Benetti <giulio.benetti at benettiengineering.com>
---
V1->V2:
* rewritten entire commit log
---
 package/qt5/qt5base/qmake.conf.in | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/package/qt5/qt5base/qmake.conf.in b/package/qt5/qt5base/qmake.conf.in
index 2eb564e172..ae25b2e20f 100644
--- a/package/qt5/qt5base/qmake.conf.in
+++ b/package/qt5/qt5base/qmake.conf.in
@@ -19,6 +19,10 @@ QMAKE_CFLAGS_OPTIMIZE       =
 QMAKE_CFLAGS_OPTIMIZE_DEBUG =
 QMAKE_CFLAGS_OPTIMIZE_FULL  =
 QMAKE_CFLAGS_OPTIMIZE_SIZE  =
+QMAKE_CFLAGS_DEBUG =
+QMAKE_CXXFLAGS_DEBUG =
+QMAKE_CFLAGS_RELEASE =
+QMAKE_CXXFLAGS_RELEASE =
 CONFIG                 += nostrip
 
 QMAKE_LIBS             += -lrt -lpthread -ldl
-- 
2.20.1