Merge bitcoin/bitcoin#22380: build: add and use C_STANDARD and CXX_STANDARD in depends

f7595f1 build: add and use CXX_STANDARD in depends (fanquake)
7e7b3e4 build: add and use C_STANDARD in depends (fanquake)

Pull request description:

  By explicitly setting a C standard version we avoid any potential for issues/differences in libraries that may come about due to C STD version, as well as avoid potentially being opted into newer code / features in libraries when compiler defaults change (i.e as of 11.0.0, Clang now defaults to gnu17 over gnu11).

  This should be a no-op for our release builds, because it's just explicitly setting the default that is [already being used](https://github.com/fanquake/core-review/blob/master/compiler-defaults.md). However this is relevant for anyone building depends with a newer compiler.

  I found [one broken `__STDC_VERSION__` check in the](miniupnp/miniupnp#552) miniupnpc header.

  At the same time, add `CXX_STANDARD` for setting our C++ standard, and use that over setting `-std=c++17` for cxx packages.

  Guix builds:
  ```bash
  ```

ACKs for top commit:
  dongcarl:
    Code Review ACK f7595f1
  laanwj:
    Code review ACK f7595f1

Tree-SHA512: 9255190d91ba3de20762b1d6af35c59d64f3d77a52bbe9a3f1dfb6bcf16daef66054ebef96b58e7285cd01bf613e69a78bd5e8681c21293e254f23d1fa7b0f71

Author: laanwj

depends/Makefile

@@ -45,6 +45,9 @@ MULTIPROCESS ?=
 LTO ?=
 FALLBACK_DOWNLOAD_PATH ?= https://bitcoincore.org/depends-sources
 
+C_STANDARD ?= c11
+CXX_STANDARD ?= c++17
+
 BUILD = $(shell ./config.guess)
 HOST ?= $(BUILD)
 PATCHES_PATH = $(BASEDIR)/patches

depends/README.md

@@ -96,6 +96,8 @@ The following can be set when running make: `make FOO=bar`
 - `BASE_CACHE`: Built packages will be placed here
 - `SDK_PATH`: Path where SDKs can be found (used by macOS)
 - `FALLBACK_DOWNLOAD_PATH`: If a source file can't be fetched, try here before giving up
+- `C_STANDARD`: Set the C standard version used. Defaults to `c11`.
+- `CXX_STANDARD`: Set the C++ standard version used. Defaults to `c++17`.
 - `NO_QT`: Don't download/build/cache Qt and its dependencies
 - `NO_QR`: Don't download/build/cache packages needed for enabling qrencode
 - `NO_ZMQ`: Don't download/build/cache packages needed for enabling ZeroMQ

depends/hosts/android.mk

@@ -6,6 +6,9 @@ android_CXX=$(ANDROID_TOOLCHAIN_BIN)/$(HOST)$(ANDROID_API_LEVEL)-clang++
 android_CC=$(ANDROID_TOOLCHAIN_BIN)/$(HOST)$(ANDROID_API_LEVEL)-clang
 endif
 
+android_CFLAGS=-std=$(C_STANDARD)
+android_CXXFLAGS=-std=$(CXX_STANDARD)
+
 ifneq ($(LTO),)
 android_CFLAGS += -flto
 android_LDFLAGS += -flto

depends/hosts/darwin.mk

@@ -109,15 +109,15 @@ darwin_CXX=env -u C_INCLUDE_PATH -u CPLUS_INCLUDE_PATH \
                -Xclang -internal-externc-isystem$(clang_resource_dir)/include \
                -Xclang -internal-externc-isystem$(OSX_SDK)/usr/include
 
-darwin_CFLAGS=-pipe
+darwin_CFLAGS=-pipe -std=$(C_STANDARD)
+darwin_CXXFLAGS=-pipe -std=$(CXX_STANDARD)
 
 ifneq ($(LTO),)
 darwin_CFLAGS += -flto
+darwin_CXXFLAGS += -flto
 darwin_LDFLAGS += -flto
 endif
 
-darwin_CXXFLAGS=$(darwin_CFLAGS)
-
 darwin_release_CFLAGS=-O2
 darwin_release_CXXFLAGS=$(darwin_release_CFLAGS)
 

depends/hosts/freebsd.mk

@@ -1,12 +1,12 @@
-freebsd_CFLAGS=-pipe
+freebsd_CFLAGS=-pipe -std=$(C_STANDARD)
+freebsd_CXXFLAGS=-pipe -std=$(CXX_STANDARD)
 
 ifneq ($(LTO),)
 freebsd_CFLAGS += -flto
+freebsd_CXXFLAGS += -flto
 freebsd_LDFLAGS += -flto
 endif
 
-freebsd_CXXFLAGS=$(freebsd_CFLAGS)
-
 freebsd_release_CFLAGS=-O2
 freebsd_release_CXXFLAGS=$(freebsd_release_CFLAGS)
 

depends/hosts/linux.mk

@@ -1,12 +1,12 @@
-linux_CFLAGS=-pipe
+linux_CFLAGS=-pipe -std=$(C_STANDARD)
+linux_CXXFLAGS=-pipe -std=$(CXX_STANDARD)
 
 ifneq ($(LTO),)
 linux_CFLAGS += -flto
+linux_CXXFLAGS += -flto
 linux_LDFLAGS += -flto
 endif
 
-linux_CXXFLAGS=$(linux_CFLAGS)
-
 linux_release_CFLAGS=-O2
 linux_release_CXXFLAGS=$(linux_release_CFLAGS)
 

depends/hosts/mingw32.mk

@@ -2,15 +2,15 @@ ifneq ($(shell $(SHELL) $(.SHELLFLAGS) "command -v $(host)-g++-posix"),)
 mingw32_CXX := $(host)-g++-posix
 endif
 
-mingw32_CFLAGS=-pipe
+mingw32_CFLAGS=-pipe -std=$(C_STANDARD)
+mingw32_CXXFLAGS=-pipe -std=$(CXX_STANDARD)
 
 ifneq ($(LTO),)
 mingw32_CFLAGS += -flto
+mingw32_CXXFLAGS += -flto
 mingw32_LDFLAGS += -flto
 endif
 
-mingw32_CXXFLAGS=$(mingw32_CFLAGS)
-
 mingw32_release_CFLAGS=-O2
 mingw32_release_CXXFLAGS=$(mingw32_release_CFLAGS)
 

depends/hosts/netbsd.mk

@@ -1,7 +1,9 @@
-netbsd_CFLAGS=-pipe
+netbsd_CFLAGS=-pipe -std=$(C_STANDARD)
+netbsd_CXXFLAGS=-pipe -std=$(CXX_STANDARD)
 
 ifneq ($(LTO),)
 netbsd_CFLAGS += -flto
+netbsd_CXXFLAGS += -flto
 netbsd_LDFLAGS += -flto
 endif
 

depends/hosts/openbsd.mk

@@ -1,8 +1,9 @@
-openbsd_CFLAGS=-pipe
-openbsd_CXXFLAGS=$(openbsd_CFLAGS)
+openbsd_CFLAGS=-pipe -std=$(C_STANDARD)
+openbsd_CXXFLAGS=-pipe -std=$(CXX_STANDARD)
 
 ifneq ($(LTO),)
 openbsd_CFLAGS += -flto
+openbsd_CXXFLAGS += -flto
 openbsd_LDFLAGS += -flto
 endif
 

depends/packages/bdb.mk

@@ -15,7 +15,6 @@ $(package)_config_opts_netbsd=--with-pic
 $(package)_config_opts_openbsd=--with-pic
 $(package)_config_opts_android=--with-pic
 $(package)_cflags+=-Wno-error=implicit-function-declaration
-$(package)_cxxflags+=-std=c++17
 $(package)_cppflags_mingw32=-DUNICODE -D_UNICODE
 endef