build: check for SetThreadDescription() at configure time #36057

ViniciusCestarii commented at 2:14 PM on August 22, 2026: contributor

SetThreadDescription() is missing from mingw-w64 headers before 12.0.0, so the Windows cross-compile fails on distro toolchains, e.g. Ubuntu 24.04. Reported by hebasto in #35884 (comment).

Check for the symbol at configure time and guard its use with a new HAVE_SETTHREADDESCRIPTION guard, as cmake/introspection.cmake already does for other optional symbols. This avoids having to declare a minimum mingw-w64 version: toolchains that have the symbol get OS-level thread names, older ones build fine without them.

DrahtBot added the label Build system on Aug 22, 2026

DrahtBot commented at 2:14 PM on August 22, 2026: contributor

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For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/36057.

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maflcko commented at 2:24 PM on August 22, 2026: member

Seems fine. An alternative would be to document the minimum required version (fac0aa7799f96c615fe361dff1a01531f741a9b5):

diff --git a/doc/build-windows.md b/doc/build-windows.md
index 0af73681d8..c47359cea3 100644
--- a/doc/build-windows.md
+++ b/doc/build-windows.md
@@ -17,2 +17,3 @@ The instructions below work on Ubuntu and Debian. Make sure the distribution's `
 package meets the minimum required GCC version specified in [dependencies.md](dependencies.md).
+At least Mingw version 12.0 is required.
 If compiling with the GUI (default in depends), at least GCC version 13 is required.

maflcko added this to the milestone 32.0 on Aug 22, 2026

hebasto commented at 2:40 PM on August 22, 2026: member

Seems fine. An alternative would be to document the minimum required version (fac0aa7):

diff --git a/doc/build-windows.md b/doc/build-windows.md
index 0af73681d8..c47359cea3 100644
--- a/doc/build-windows.md
+++ b/doc/build-windows.md
@@ -17,2 +17,3 @@ The instructions below work on Ubuntu and Debian. Make sure the distribution's `
 package meets the minimum required GCC version specified in [dependencies.md](dependencies.md).
+At least Mingw version 12.0 is required.
 If compiling with the GUI (default in depends), at least GCC version 13 is required.

I think it would be good to document the minimum required version regardless of whether we check for symbol availability. Setting it to 12.0 seems fine to me.

maflcko commented at 2:47 PM on August 22, 2026: member

Hmm, if it is set to 12, then we don't really need the changes here?

No strong opinion, but maybe do the changes here for 32.x and then remove them again and bump mingw to 13 for 33.x, as that is required for the next QT bump and libmultiprocess+Windows anyway?

hebasto commented at 2:53 PM on August 22, 2026: member

No strong opinion, but maybe do the changes here for 32.x and then remove them again and bump mingw to 13 for 33.x, as that is required for the next QT bump and libmultiprocess+Windows anyway?

I agree. @ViniciusCestarii Please add documenting commit.

hebasto commented at 2:55 PM on August 22, 2026: member

And please consider the related #36029.

ViniciusCestarii commented at 7:34 PM on August 22, 2026: contributor

Pushed ecb5bf8400686183c40731da19dd3c9e46bb7c19 documenting the minimum required Mingw-w64 version.

hebasto commented at 9:51 AM on August 24, 2026: member

Hmm, if it is set to 12, then we don't really need the changes here?

I do apologise for the confusion I caused. Indeed, only one of the two commits is needed.

ViniciusCestarii force-pushed on Aug 24, 2026

ViniciusCestarii commented at 12:33 PM on August 24, 2026: contributor

Forced push fd4e1636ed1a4d691c2a345b9881cd88f8b31fa7 removing the minimum required Mingw-w64 version from docs. Better to enforce Mingw-w64 minimum version with the next QT bump and libmultiprocess+Windows as justification than only named Windows threads.

hebasto approved

hebasto commented at 2:22 PM on August 24, 2026: member

ACK fd4e1636ed1a4d691c2a345b9881cd88f8b31fa7. Tested here.

in cmake/introspection.cmake:81 in fd4e1636ed

  75 | @@ -76,6 +76,12 @@ check_cxx_source_compiles("
  76 |    " HAVE_STRONG_GETAUXVAL
  77 |  )
  78 |  
  79 | +# Check for SetThreadDescription(), which is missing from mingw-w64 headers
  80 | +# before 12.0.0.
  81 | +if(WIN32)

fanquake commented at 2:27 PM on August 24, 2026:

This doesn't need to be gated on WIN32.

ViniciusCestarii commented at 4:45 PM on August 26, 2026:

true, thanks. Done on bed46bd16c2b34eec62849b96cebbbdbcdd2c1ac

fanquake commented at 3:09 PM on August 24, 2026: member

Looking at this further. #32380 changed our minimum supported/tested Windows version to Windows 10 (version 1903), and SetThreadDescription has been available since Windows 10, version 1607. Devs should be free to use any functions available in a version earlier than 1903, without having to check for availability. So it seems like the mingw-w64 requirements were missing from #32380, or we are still trying to support a version of mingw-w64 which isn't compatible with our minimum version requirements?

fanquake commented at 1:20 PM on August 26, 2026: member

@hebasto can you followup here in regards to #32380, and what our minimum supported build/runtime Windows versions already are?

maflcko commented at 1:43 PM on August 26, 2026: member

I think it is fine to have this check for 32.x. A larger sweep+bump can happen in 33.x

hebasto commented at 1:49 PM on August 26, 2026: member

Looking at this further. #32380 changed our minimum supported/tested Windows version to Windows 10 (version 1903), and SetThreadDescription has been available since Windows 10, version 1607. Devs should be free to use any functions available in a version earlier than 1903, without having to check for availability. So it seems like the mingw-w64 requirements were missing from #32380...

I concur. Indeed, #32380 implicitly set the minimum required mingw-w64 version to 12.0.

or we are still trying to support a version of mingw-w64 which isn't compatible with our minimum version requirements?

No, I don't think we should.

build: check for SetThreadDescription() at configure time bed46bd16c

ViniciusCestarii force-pushed on Aug 26, 2026

ViniciusCestarii commented at 4:48 PM on August 26, 2026: contributor

Thanks for the reviews. Forced push bed46bd16c2b34eec62849b96cebbbdbcdd2c1ac dropping the unnecessary check for WIN on introspection.cmake, addressing #36057 (review)

fanquake commented at 2:50 PM on August 27, 2026: member

utACK bed46bd16c2b34eec62849b96cebbbdbcdd2c1ac - could be reverted + docs updated post branch-off.

DrahtBot requested review from hebasto on Aug 27, 2026

hebasto approved

hebasto commented at 10:10 PM on August 27, 2026: member

re-ACK bed46bd16c2b34eec62849b96cebbbdbcdd2c1ac.

hebasto merged this on Aug 27, 2026

hebasto closed this on Aug 27, 2026

maflcko commented at 8:22 AM on August 28, 2026: member

So I guess there could be a new pull request (with a target of the next 33.x milestone), which:

Reverts this commit
Applies the doc min version of 12.0 (https://github.com/bitcoin/bitcoin/pull/36057#issuecomment-5380890754)
open question: Requires that version/symbol in cmake/module/CheckCXXFeatures.cmake for a nicer UX to fail compile early instead of later? (not sure if worth it)