using internal linking, cmd/link can generate Go binaries by itself.

In order to allow linking arbitrary object files without requiring
dynamic libraries, cgo supports an "external" linking mode too. In
external linking mode, cmd/link does not process any host object files.
Instead, it collects all the Go code and writes a single go.o object
file containing it. Then it invokes the host linker (usually gcc) to

    visibility = ["//visibility:public"],
)

# The interface library (tensorflow.dll.if.lib) for linking tensorflow DLL library (tensorflow.dll) on Windows.
# To learn more about import library (called interface library in Bazel):
#     https://docs.microsoft.com/en-us/cpp/build/linking-an-executable-to-a-dll?view=vs-2017#linking-implicitly
filegroup(
    name = "get_tensorflow_dll_import_lib",

      --enable-initfini-array \
      --enable-languages="c,c++" \
      --enable-linker-build-id \
      --enable-plugin \
      --enable-shared \
      --enable-threads=posix \
      --with-default-libstdcxx-abi=${LIBSTDCXX_ABI} \
      --with-gcc-major-version-only \
      --with-linker-hash-style="gnu" \
      && \
      make -j$(nproc) && \
      make install

      --enable-initfini-array \
      --enable-languages="c,c++" \
      --enable-linker-build-id \
      --enable-plugin \
      --enable-shared \
      --enable-threads=posix \
      --with-default-libstdcxx-abi=${LIBSTDCXX_ABI} \
      --with-gcc-major-version-only \
      --with-linker-hash-style="gnu" \
      --with-tune="generic" \
      && \
    make -j 42 && \
    make install

	MOVQ R15, AX // ERROR "when dynamic linking, R15 is clobbered by a global variable access and is used here"
	RET
TEXT ·a8(SB), 0, $0-0
	CMPL runtime·writeBarrier(SB), $0
	ADDQ AX, R15 // ERROR "when dynamic linking, R15 is clobbered by a global variable access and is used here"
	RET
TEXT ·a9(SB), 0, $0-0
	CMPL runtime·writeBarrier(SB), $0

          if (retryMs != -1L) {
            callback.onRetryChange(retryMs)
          }
        }

        -1 -> {
          val lineEnd = source.indexOfElement(CRLF)
          if (lineEnd != -1L) {
            // Skip the line and newline
            source.skip(lineEnd)
            source.select(options)
          } else {
            return false // No more newlines.
          }
        }

   * high 32 bits of each long is the "prev" pointer, whereas the low 32 bits is the "succ" pointer
   * (pointing to the next entry in the linked list). The pointers in [size(), entries.length) are
   * all "null" (UNSET).
   *
   * <p>A node with "prev" pointer equal to {@code ENDPOINT} is the first node in the linked list,
   * and a node with "next" pointer equal to {@code ENDPOINT} is the last node.
   */

   * high 32 bits of each long is the "prev" pointer, whereas the low 32 bits is the "succ" pointer
   * (pointing to the next entry in the linked list). The pointers in [size(), entries.length) are
   * all "null" (UNSET).
   *
   * <p>A node with "prev" pointer equal to {@code ENDPOINT} is the first node in the linked list,
   * and a node with "next" pointer equal to {@code ENDPOINT} is the last node.
   */

	Shared     = flag.Bool("shared", false, "generate code that can be linked into a shared library")
	Dynlink    = flag.Bool("dynlink", false, "support references to Go symbols defined in other shared libraries")
	Linkshared = flag.Bool("linkshared", false, "generate code that will be linked against Go shared libraries")
	AllErrors  = flag.Bool("e", false, "no limit on number of errors reported")

a C source file for 6c; both compile as part of the named package
(gmp, in this example).  The third, gcc.c, is a C source file for gcc;
it compiles into a shared object (.so) that is dynamically linked into
any 6.out that imports the first two files.

The stanza

	// #include <gmp.h>
	import "C"

is a signal to cgo.  The doc comment on the import of "C" provides