Description of problem:
With GCC update to version 7, I'm not able to build the newest squid only on arm arch. On all other archs, build succeeded. 

https://koji.fedoraproject.org/koji/taskinfo?taskID=18814683

Version-Release number of selected component (if applicable):
gcc-c++-7.0.1-0.13.fc27.armv7hl

How reproducible:
Try to build newest squid package in Fedora RAWHIDE

Steps to Reproduce:
1. fedpkg clone squid
2. fedpkg build --scratch
3. 

Actual results:
Squid build fails only on ARM

Expected results:
Squid build succeeded on all archs

Additional info:

Problem also occurred, when I reserved ARM machine and manually tried to compile HttpMsg.cc:

# make HttpMsg.o
armv7hl-redhat-linux-gnueabi-g++ -DHAVE_CONFIG_H -DDEFAULT_CONFIG_FILE=\"/etc/squid/squid.conf\" -DDEFAULT_SQUID_DATA_DIR=\"/usr/share/squid\" -DDEFAULT_SQUID_CONFIG_DIR=\"/etc/squid\"   -I.. -I../include -I../lib -I../src -I../include    -I../src   -I/usr/include/libxml2  -I/usr/include/libxml2 -Wall -Wpointer-arith -Wwrite-strings -Wcomments -Wshadow -Woverloaded-virtual -Werror -pipe -D_REENTRANT -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64  -O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -march=armv7-a -mfpu=vfpv3-d16  -mfloat-abi=hard -fPIC -save-temps -c -o HttpMsg.o HttpMsg.cc
armv7hl-redhat-linux-gnueabi-g++: warning: -pipe ignored because -save-temps specified
In file included from http/one/Parser.h:12:0,
                 from HttpMsg.cc:13:
../src/anyp/ProtocolVersion.h: In constructor ‘HttpMsg::HttpMsg(http_hdr_owner_type)’:
../src/anyp/ProtocolVersion.h:34:83: error: ‘<anonymous>’ is used uninitialized in this function [-Werror=uninitialized]
     ProtocolVersion(ProtocolType which, unsigned int aMajor, unsigned int aMinor) : protocol(which) {
                                                                                   ^
../src/anyp/ProtocolVersion.h: In constructor ‘HttpMsg::HttpMsg(http_hdr_owner_type)’:
../src/anyp/ProtocolVersion.h:34:83: error: ‘<anonymous>’ is used uninitialized in this function [-Werror=uninitialized]
     ProtocolVersion(ProtocolType which, unsigned int aMajor, unsigned int aMinor) : protocol(which) {
                                                                                   ^
cc1plus: all warnings being treated as errors

I'm attaching HttpMsg.cc , HttpMsg.ii and /src/anyp/ProtocolVersion.h files.