[win] Fix source build without pre-built deps

[inkydragon]

fix #45645, #45745

[vtjnash]

Seems unlikely this should care about the BUILD_OS

[inkydragon]

Yes, it's a workaround for cygwin.
I'm not sure if there is a better solution.

It's incredibly frustrating to build p7zip on mingw, so instead we just redistribute 7z
https://github.com/JuliaPackaging/Yggdrasil/blob/b2e0c2c5851b71230fb7170f74d773393ce37f80/P/p7zip/build_tarballs.jl#L21

In my case, on Windows, build p7zip with gcc on cygwin, works well.
But when cross build p7zip with x86_64-w64-mingw32-gcc it fails.

[metab0t]

Some suggestions:

1. According to
   

   julia/Make.inc

   Lines 545 to 550 in 3df39c0

   	CC_BASE := $(shell echo $(CC) | cut -d' ' -f1)
   	CC_ARG := $(shell echo $(CC) | cut -s -d' ' -f2-)
   	CXX_BASE := $(shell echo $(CXX) | cut -d' ' -f1)
   	CXX_ARG := $(shell echo $(CXX) | cut -s -d' ' -f2-)
   	FC_BASE := $(shell echo $(FC) | cut -d' ' -f1)
   	FC_ARG := $(shell echo $(FC) | cut -s -d' ' -f2-)

   
   Maybe we should use

CC=$(CC_BASE) CFLAGS=$(CC_ARG) CXX=$(CXX_BASE) CXXFLAGS=$(CXX_ARG) FC=$(FC_BASE) FCFLAGS=$(FC_ARG)

for Makefile-based dep.

2. For p7zip, we can set USE_BINARYBUILDER_P7ZIP=1 when cross compiling to Windows. It is an external tool.

3. It seems that LLVM_CMAKE in llvm.mk should be initialized with $(CMAKE_COMMON)?

4. We should add CC_FOR_BUILD=$(HOSTCC) before GMP configure. It is crucial for Linux cross compiler.
   Ref:
   https://gmplib.org/manual/Build-Options
   https://aur.archlinux.org/cgit/aur.git/tree/PKGBUILD?h=mingw-w64-gmp#n22

[inkydragon]

1. Maybe we should use ... for Makefile-based dep.

julia/deps/tools/common.mk

Line 58 in 7838124

MAKE_COMMON := DESTDIR="" prefix=$(build_prefix) bindir=$(build_depsbindir) libdir=$(build_libdir) shlibdir=$(build_shlibdir) libexecdir=$(build_libexecdir) datarootdir=$(build_datarootdir) includedir=$(build_includedir) sysconfdir=$(build_sysconfdir) O=

Yes, we can add those flags to MAKE_COMMON

2. For p7zip, we can set USE_BINARYBUILDER_P7ZIP=1 when cross compiling to Windows. It is an external tool.

But it will break offline build steps.
It might be worth creating a new issue to discuss the 7z build.

3. It seems that LLVM_CMAKE in llvm.mk should be initialized with $(CMAKE_COMMON)?

julia/deps/llvm.mk

Line 238 in 7838124

$(CMAKE) $(SRCCACHE)/$(LLVM_SRC_DIR)/llvm $(CMAKE_GENERATOR_COMMAND) $(CMAKE_COMMON) $(LLVM_CMAKE) \

Well hidden

4. We should add CC_FOR_BUILD=$(HOSTCC) before GMP configure. It is crucial for Linux cross compiler.

Maybe in another pr?

OK, done. And I'm testing cross build on WSL2.

[inkydragon]

I would like to split this pr into a series of smaller pr's for easier review:

• [deps/llvm] don't use hardcode LLVM_SHARED_LIB_NAME #45908
• TODO