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digitalmars.D.ldc - warning: overriding '-mmacosx-version-min=10.14' option

reply Jacob Carlborg <doob me.com> writes:
When compiling the runtime for iOS using `ldc-build-runtime` using the 
following command:

ldc-build-runtime \
--cFlags='-target arm64-apple-ios12.0;-isysroot $IOS_SDK_PATH' \
--linkerFlags='-target arm64-apple-ios12.0;-isysroot $IOS_SDK_PATH' \
--dFlags='-mtriple=arm64-apple-ios12.0;-w;-de;-dip1000' \
--ldc=~/ldc/build/bin/ldc2 \
--ldcSrcDir=~/ldc \
--ninja \
--testrunners

I get warnings like this:

clang: warning: overriding '-mmacosx-version-min=10.14' option with 
'--target=arm64-apple-ios12.0' [-Woverriding-t-option]

Looking at the `build.ninja` file that is generated there are 72 targets 
(or whatever they're called) that contains the following:

FLAGS = -DHAVE_UNISTD_H -isysroot $MAC_OSX_SDK_PATH 
-mmacosx-version-min=10.14   -target arm64-apple-ios12.0 -isysroot 
$IOS_SDK_PATH

(I've replaced the actual SDK paths with $MAC_OSX_SDK_PATH and 
$IOS_SDK_PATH to reduce the text).

-- 
/Jacob Carlborg
Jan 11 2020
parent reply kinke <noone nowhere.com> writes:
On Saturday, 11 January 2020 at 11:15:52 UTC, Jacob Carlborg 
wrote:

 I get warnings like this:

 clang: warning: overriding '-mmacosx-version-min=10.14' option 
 with '--target=arm64-apple-ios12.0' [-Woverriding-t-option]

 Looking at the `build.ninja` file that is generated there are 
 72 targets (or whatever they're called) that contains the 
 following:

 FLAGS = -DHAVE_UNISTD_H -isysroot $MAC_OSX_SDK_PATH 
 -mmacosx-version-min=10.14   -target arm64-apple-ios12.0 
 -isysroot $IOS_SDK_PATH

 (I've replaced the actual SDK paths with $MAC_OSX_SDK_PATH and 
 $IOS_SDK_PATH to reduce the text).


Without specifying a C cross-compiler directly, either via 
setting the CC env variable or by using a CMake toolchain file, 
CMake will probe and configure the compiler for the host.

There are probably guides for how to set up CMake 
cross-compilation from macOS to iOS. There might even be some 
builtin CMake support in the meantime: 
https://gitlab.kitware.com/cmake/cmake/issues/17870


 --cFlags='-target arm64-apple-ios12.0;-isysroot $IOS_SDK_PATH' \
 --linkerFlags='-target arm64-apple-ios12.0;-isysroot 
 $IOS_SDK_PATH' \


The spaces here should be replaced by semicolons.
Jan 12 2020
parent reply Jacob Carlborg <doob me.com> writes:
On 2020-01-12 13:02, kinke wrote:


 Without specifying a C cross-compiler directly, either via setting the 
 CC env variable or by using a CMake toolchain file, CMake will probe and 
 configure the compiler for the host.


Aha, I see. So I've been lucky so far that is has worked. Probably 
because the Posix layer on macOS and iOS is basically the same.

Originally I did what Xcode is doing. It invokes the same compiler 
regardless the target platform. I just specifies different target 
triples with the `-target` flag and different SDKs with the `-isysroot` 
flag. As far as I know there's never been a compiler that targets a 
specific platform by Apple. They have always used flags like above 
mentioned.


 There are probably guides for how to set up CMake cross-compilation from 
 macOS to iOS. There might even be some builtin CMake support in the 
 meantime: https://gitlab.kitware.com/cmake/cmake/issues/17870


Yeah, I found some documentation now [1], seems to be officially 
supported. Seems to work like this:

* CMAKE_SYSTEM_NAME - Specifies the target platform. Will detect the 
correct SDK. This adds the `-isysroot` flag.

* CMAKE_OSX_ARCHITECTURES - Specifies the target architecture. This will 
add the `-arch` flag.

* CMAKE_OSX_DEPLOYMENT_TARGET - Specifies the minimal deployment target. 
This will (for iOS) add the `-miphoneos-version-min` flag.

The flags `-arch arm64 -miphoneos-version-min=12.0` will give the same 
binary as `-target arm64-apple-ios12.0`.

Although, I still need to specify 
`--cFlags='-target;arm64-apple-ios12.0'` otherwise the assembly files 
(threadasm.S and eh_asm.S) are compiled for macOS x86-64 instead of iOS 
ARM64. Not sure if that's a bug in CMake or in the LDC configuration.


 The spaces here should be replaced by semicolons.


Ok, I see.

[1] 
https://cmake.org/cmake/help/latest/manual/cmake-toolchains.7.html#cross-compiling-for-ios-tvos-or-watchos

-- 
/Jacob Carlborg
Jan 15 2020
parent Jacob Carlborg <doob me.com> writes:
On 2020-01-15 20:55, Jacob Carlborg wrote:


 * CMAKE_SYSTEM_NAME - Specifies the target platform. Will detect the 
 correct SDK. This adds the `-isysroot` flag.
 
 * CMAKE_OSX_ARCHITECTURES - Specifies the target architecture. This will 
 add the `-arch` flag.
 
 * CMAKE_OSX_DEPLOYMENT_TARGET - Specifies the minimal deployment target. 
 This will (for iOS) add the `-miphoneos-version-min` flag.


To be clear, when specifying these CMake variables the warning 
disappears. Thanks.

-- 
/Jacob Carlborg
Jan 15 2020