NOTE: Although the original bug report could be closed as "Not an Issue," it was difficult enough to track down the true source of the error that it's worth making a code changes to help anyone else who hits the problem.

ORIGINAL DESCRIPTION

The build of JavaFX on Windows fails with the messages:

  FAILURE: Build failed with an exception.

  * Where:
  Script 'C:\cygwin64\home\john\src\jfx\buildSrc\win.gradle' line: 105

  * What went wrong:
  A problem occurred evaluating script.
  > FAIL: WINSDK_DIR not defined

SYSTEM / OS / JAVA RUNTIME INFORMATION

Microsoft Windows 10 Pro Version 10.0.19042

  $ uname -srm
  CYGWIN_NT-10.0 3.2.0(0.340/5/3) x86_64

Oracle OpenJDK 15.0.2

  $ java --version
  openjdk 15.0.2 2021-01-19
  OpenJDK Runtime Environment (build 15.0.2+7-27)
  OpenJDK 64-Bit Server VM (build 15.0.2+7-27, mixed mode, sharing)

Apache Ant 1.10.9

  $ ant -version
  Apache Ant(TM) version 1.10.9 compiled on September 27 2020

Gradle 6.3

  $ gradle --version

  ------------------------------------------------------------
  Gradle 6.3
  ------------------------------------------------------------

  Build time: 2020-03-24 19:52:07 UTC
  Revision: bacd40b727b0130eeac8855ae3f9fd9a0b207c60

  Kotlin: 1.3.70
  Groovy: 2.5.10
  Ant: Apache Ant(TM) version 1.10.7 compiled on September 1 2019
  JVM: 15.0.2 (Oracle Corporation 15.0.2+7-27)
  OS: Windows 10 10.0 amd64

STEPS TO REPRODUCE

Follow the instructions for building JavaFX on Windows found here:

Building OpenJFX
https://wiki.openjdk.java.net/display/OpenJFX/Building+OpenJFX

Run a build. For example, I ran:

  $ gradle sdk jmods javadoc

EXPECTED RESULTS

The build succeeds:

  BUILD SUCCESSFUL in 7m 11s
  139 actionable tasks: 139 executed

ACTUAL RESULT

The build fails:

  FAILURE: Build failed with an exception.

  * Where:
  Script 'C:\cygwin64\home\john\src\jfx\buildSrc\win.gradle' line: 105

  * What went wrong:
  A problem occurred evaluating script.
  > FAIL: WINSDK_DIR not defined
  ...
  BUILD FAILED in 11s

SOURCE CODE FOR AN EXECUTABLE TEST CASE

None.

WORKAROUND

I was able to work around the problem by manually creating the file 'windows_tools.properties' as instructed in the section below:

Missing paths issue
https://wiki.openjdk.java.net/display/OpenJFX/Building+OpenJFX#BuildingOpenJFX-Missingpathsissue

The following files are attached to this bug report:

  windows_tools.properties - the file I used
  windows_tools.properties.txt - a version that's easier to read