build: allow fallback for `CMAKE_Swift_COMPILER` migration #38239

compnerd · 2021-07-02T22:14:26Z

The original change c0d6d8f added a
soft migration path from SWIFT_NATIVE_SWIFT_TOOLS_PATH to
CMAKE_Swift_COMPILER, which broke some setups. Subsequently
9da7665 added an overly restrictive
check to ensure that CMAKE_Swift_COMPILER is always set when
SWIFT_BUILD_RUNTIME_WITH_HOST_COMPILER is set. This loosens the check
to ensure that either CMAKE_Swift_COMPILER or
SWIFT_NATIVE_SWIFT_TOOLS_PATH can be used during the migration.

Replace this paragraph with a description of your changes and rationale. Provide links to external references/discussions if appropriate.

Resolves SR-NNNN.

The original change c0d6d8f added a soft migration path from `SWIFT_NATIVE_SWIFT_TOOLS_PATH` to `CMAKE_Swift_COMPILER`, which broke some setups. Subsequently 9da7665 added an overly restrictive check to ensure that `CMAKE_Swift_COMPILER` is always set when `SWIFT_BUILD_RUNTIME_WITH_HOST_COMPILER` is set. This loosens the check to ensure that either `CMAKE_Swift_COMPILER` or `SWIFT_NATIVE_SWIFT_TOOLS_PATH` can be used during the migration.

compnerd · 2021-07-02T22:14:34Z

CC: @davezarzycki

compnerd · 2021-07-02T22:14:44Z

@swift-ci please test

compnerd · 2021-07-02T22:38:32Z

Running a nightly build for Windows at https://dev.azure.com/compnerd/swift-build/_build/results?buildId=52716&view=results

davezarzycki

Verified. I restored my setup to how it was before #38123. That is to say, I changed my build scripts to no longer let Swift's CMake find the installed swift once again. I then applied #38238, this pull request, and did a clean build. Everything works. Thanks!

davezarzycki

Wait, I forgot a restorative change. The bug still exists:

cd /home/dave/b/u/t/tools/swift/stdlib/public/core && /usr/bin/python3.9 /home/dave/ro_s/u/swift/utils/line-directive @/home/dave/b/u/t/tools/swift/stdlib/public/core/dfaab9867ab9868918d54c7626d620fe0cb9c79c.txt -- -c -sdk / -target x86_64-unknown-linux-gnu -resource-dir /home/dave/b/u/t/./lib/swift -O -D INTERNAL_CHECKS_ENABLED -D SWIFT_RUNTIME_OS_VERSIONING -module-cache-path /home/dave/b/u/t/./module-cache -no-link-objc-runtime -enable-library-evolution -Xfrontend -enforce-exclusivity=unchecked -nostdimport -parse-stdlib -module-name Swift -Xfrontend -group-info-path -Xfrontend /home/dave/ro_s/u/swift/stdlib/public/core/GroupInfo.json -swift-version 5 -runtime-compatibility-version none -disable-autolinking-runtime-compatibility-dynamic-replacements -warn-swift3-objc-inference-complete -Xfrontend -verify-syntax-tree -Xllvm -sil-inline-generics -Xllvm -sil-partial-specialization -Xfrontend -enable-experimental-concise-pound-file -Xfrontend -enable-ossa-modules -Xcc -DswiftCore_EXPORTS -warn-implicit-overrides -module-link-name swiftCore -whole-module-optimization -parse-as-library -I /home/dave/b/u/t/./lib/swift/linux -o /home/dave/b/u/t/tools/swift/stdlib/public/core/LINUX/x86_64/Swift.o @/home/dave/b/u/t/tools/swift/stdlib/public/core/dfaab9867ab9868918d54c7626d620fe0cb9c79c.txt
Traceback (most recent call last):
  File "/home/dave/ro_s/u/swift/utils/line-directive", line 742, in <module>
    run()
  File "/home/dave/ro_s/u/swift/utils/line-directive", line 694, in run
    command = subprocess.Popen(
  File "/usr/lib64/python3.9/subprocess.py", line 951, in __init__
    self._execute_child(args, executable, preexec_fn, close_fds,
  File "/usr/lib64/python3.9/subprocess.py", line 1821, in _execute_child
    raise child_exception_type(errno_num, err_msg, err_filename)
FileNotFoundError: [Errno 2] No such file or directory: '-c'

davezarzycki · 2021-07-03T02:49:43Z

Weird, the following results in NOTFOUND and FALSE respectively but no error is generated:

if (SWIFT_BUILD_RUNTIME_WITH_HOST_COMPILER)
  if (NOT CMAKE_Swift_COMPILER AND NOT SWIFT_PREBUILT_SWIFT)
    message(ERROR "Swift Compiler not found and SWIFT_BUILD_RUNTIME_WITH_HOST_COMPILER is set")
  endif()
endif()

compnerd · 2021-07-03T03:41:56Z

Huh? That sounds like the issue, but why?

Add a workaround for `NOT CMAKE_Swift_COMPILER` not evaluating properly.

compnerd · 2021-07-03T03:54:19Z

@davezarzycki - I added a horrible workaround to the CMake in the hopes that it evaluates properly.

davezarzycki

So overall, after the STREQUAL fix, the net result is the same to me. I can't use SWIFT_BUILD_RUNTIME_WITH_HOST_COMPILER anymore unless I supply a pre-built Swift, which if that's the goal, then fine, I can live without SWIFT_BUILD_RUNTIME_WITH_HOST_COMPILER.

CC @gottesmm

davezarzycki · 2021-07-03T11:20:12Z

CMakeLists.txt

 if (SWIFT_BUILD_RUNTIME_WITH_HOST_COMPILER)
-  if (NOT CMAKE_Swift_COMPILER AND NOT SWIFT_PREBUILT_SWIFT)
+  if ("${CMAKE_Swift_COMPILER}" STREQUAL "CMAKE_Swift_COMPILER-NOTFOUND" AND NOT SWIFT_PREBUILT_SWIFT)


In my testing and debugging, it needs to be: "${CMAKE_Swift_COMPILER}" STREQUAL "NOTFOUND"

compnerd · 2021-07-04T05:01:20Z

Wait, I'm not sure how the build is supposed to work in this case. You are saying that CMake doesn't find the Swift compiler nor is SWIFT_PREBUILT_SWIFT set, so how is it supposed to find swiftc? Is the expectation that it will find it in the path?

davezarzycki · 2021-07-04T11:30:02Z

One of the supported build modes uses the just built swiftc to compile swift code (see the top level CMakeLists.txt, line 578). But after @gottesmm's change, this mode became incompatible with SWIFT_BUILD_RUNTIME_WITH_HOST_COMPILER.

compnerd · 2021-07-04T16:54:45Z

Ah, for that I think that we should definitely get @gottesmm's opinion on introducing a more precise SWIFT_BUILD_SWIFT_STANDARD_LIBRARY_WITH_HOST_COMPILER instead of misattributing the compilation of the standard library to the runtime. The runtime is technically below the standard library, and building that with the host compiler is different than building the stdlib with the host compiler.

davezarzycki · 2021-07-04T18:07:09Z

Right, I was allowing for a liberal definition of "runtime" or that the build variable name was no longer ideal but otherwise ya, we need @gottesmm's input.

davezarzycki · 2021-07-12T11:57:46Z

@gottesmm -- ping?

davezarzycki · 2021-08-28T10:15:00Z

@gottesmm -- ping?

compnerd · 2023-03-29T01:11:26Z

This is woefully out of date at this point, closing this off. I imagine that is now longer valuable.

compnerd mentioned this pull request Jul 2, 2021

Revert "[CMake] Better dependency checking" #38238

Merged

davezarzycki self-requested a review July 3, 2021 02:26

davezarzycki approved these changes Jul 3, 2021

View reviewed changes

davezarzycki requested changes Jul 3, 2021

View reviewed changes

Update CMakeLists.txt

6cc8721

Add a workaround for `NOT CMAKE_Swift_COMPILER` not evaluating properly.

davezarzycki requested changes Jul 3, 2021

View reviewed changes

compnerd closed this Mar 29, 2023

compnerd deleted the lax-checking branch March 29, 2023 01:11

build: allow fallback for CMAKE_Swift_COMPILER migration #38239

build: allow fallback for CMAKE_Swift_COMPILER migration #38239

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build: allow fallback for `CMAKE_Swift_COMPILER` migration #38239

build: allow fallback for `CMAKE_Swift_COMPILER` migration #38239