Specifying go build's version of C++ - c++

Question

I'm trying to build a go project that uses a third party library (GDAL) that's written in C and C++. I've run into this error:
In file included from contour.cpp:31:0:
cpl_port.h:187:6: error: #error Must have C++11 or newer.
# error Must have C++11 or newer.
^
In file included from C:/TDM-GCC-64/lib/gcc/x86_64-w64-mingw32/5.1.0/include/c++/type_traits:35:0,
from cpl_conv.h:372,
from contour.cpp:39:
C:/TDM-GCC-64/lib/gcc/x86_64-w64-mingw32/5.1.0/include/c++/bits/c++0x_warning.h:32:2: error: #error This file requires compiler and library support for the ISO C++ 2011 standard. This support is currently experimental, and must be enabled with the -std=c++11 or -std=gnu++11 compiler options.
#error This file requires compiler and library support for the \
^
Some searching tells me this is expected, and the fix is to simply set a flag on the compiler (not go related, but still pertinent).
I've read through go's documentation on building, and while it suggests it's possible to specify options to individual compilers, it doesn't explicitly spell out how, nor does it provide any examples.
I've tried the following just guessing, and while the go build command accepts them, they produce the same error, so they don't work.
go build -gcflags -std=gnu++11 -ldflags -std=gnu++11
go build -gcflags -std=c++11 -ldflags -std=c++11
go build -gcflags -std=c++11
go build -gcflags -std=all=gnu++11 -ldflags -std=all=gnu++11
How can I tell go to tell gcc to compile with C++11 or newer?
Edit: As requested by PeterSO:
H:\>go version
go version go1.10.2 windows/amd64
H:\>go env
set GOARCH=amd64
set GOBIN=
set GOCACHE=C:\Users\ksexton\AppData\Local\go-build
set GOEXE=.exe
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOOS=windows
set GOPATH=H:\ksexton\Go;
set GORACE=
set GOROOT=C:\Go
set GOTMPDIR=
set GOTOOLDIR=C:\Go\pkg\tool\windows_amd64
set GCCGO=gccgo
set CC=gcc
set CXX=g++
set CGO_ENABLED=1
set CGO_CFLAGS=-g -O2
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-g -O2
set CGO_FFLAGS=-g -O2
set CGO_LDFLAGS=-g -O2
set PKG_CONFIG=pkg-config
set GOGCCFLAGS=-m64 -mthreads -fmessage-length=0 -fdebug-prefix-map=C:\Users\ksexton\AppData\Local\Temp\go-build937852322=/tmp/go-build -gno-record-gcc-switches
H:\>gcc --version
gcc (tdm64-1) 5.1.0
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
H:\>g++ --version
g++ (tdm64-1) 5.1.0
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Answer 1

Command cgo
Using cgo with the go command
All the cgo CPPFLAGS and CFLAGS directives in a package are
concatenated and used to compile C files in that package. All the
CPPFLAGS and CXXFLAGS directives in a package are concatenated and
used to compile C++ files in that package. All the CPPFLAGS and FFLAGS
directives in a package are concatenated and used to compile Fortran
files in that package. All the LDFLAGS directives in any package in
the program are concatenated and used at link time. All the pkg-config
directives are concatenated and sent to pkg-config simultaneously to
add to each appropriate set of command-line flags.
On Windows:
set CGO_CXXFLAGS=-std=c++11