[bug#39742] [v2] gnu: java-openjfx-build: Add helpful patch.

[Alexey Abramov]

* gnu/packages/java.scm (java-openjfx-build)[source]: Use it.
* gnu/packages/patches/java-openjfx-build-get_guix_jdk_version.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
---
 gnu/local.mk                                  |  1 +
 gnu/packages/java.scm                         |  3 +-
 ...a-openjfx-build-get_guix_jdk_version.patch | 37 +++++++++++++++++++
 3 files changed, 40 insertions(+), 1 deletion(-)
 create mode 100644 
gnu/packages/patches/java-openjfx-build-get_guix_jdk_version.patch

diff --git a/gnu/local.mk b/gnu/local.mk
index f6c56ceb28..0bcbde7301 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -1033,6 +1033,7 @@ dist_patch_DATA =                                         
\
   %D%/packages/patches/java-apache-ivy-port-to-latest-bouncycastle.patch       
\
   %D%/packages/patches/java-commons-collections-fix-java8.patch \
   %D%/packages/patches/java-jeromq-fix-tests.patch             \
+  %D%/packages/patches/java-openjfx-build-get_guix_jdk_version.patch    \
   %D%/packages/patches/java-powermock-fix-java-files.patch             \
   %D%/packages/patches/java-simple-xml-fix-tests.patch         \
   %D%/packages/patches/java-svg-salamander-Fix-non-det.patch   \
diff --git a/gnu/packages/java.scm b/gnu/packages/java.scm
index 5229eeda06..a46d4013d8 100644
--- a/gnu/packages/java.scm
+++ b/gnu/packages/java.scm
@@ -2361,7 +2361,8 @@ new Date();"))
                   #t))
               (sha256
                (base32
-                "0yg38mwpivswccv9n96k06x3iv82i4px1a9xg9l8dswzwmfj259f"))))
+                "0yg38mwpivswccv9n96k06x3iv82i4px1a9xg9l8dswzwmfj259f"))
+              (patches (search-patches 
"java-openjfx-build-get_guix_jdk_version.patch"))))
     (build-system ant-build-system)
     (arguments
      `(#:jar-name "java-openjfx.jar"
diff --git a/gnu/packages/patches/java-openjfx-build-get_guix_jdk_version.patch 
b/gnu/packages/patches/java-openjfx-build-get_guix_jdk_version.patch
new file mode 100644
index 0000000000..4ebdadc671
--- /dev/null
+++ b/gnu/packages/patches/java-openjfx-build-get_guix_jdk_version.patch
@@ -0,0 +1,37 @@
+From d156313340d3edcd78751ea8ed5e66c7668275c3 Mon Sep 17 00:00:00 2001
+From: Alexey Abramov <address@hidden>
+Date: Sun, 8 Mar 2020 20:07:22 +0100
+Subject: [PATCH] openjfx: Determine the version of Java in JDK_HOME
+
+Icedtea contains guix in its version, so build.gradle failes to run. Openjfx
+packaging is not trivial, so you will probably need to try build it with
+gradlew.
+
+---
+ build.gradle | 5 ++---
+ 1 file changed, 2 insertions(+), 3 deletions(-)
+
+diff --git a/build.gradle b/build.gradle
+index df82f63..2c626cd 100644
+--- a/build.gradle
++++ b/build.gradle
+@@ -742,9 +742,9 @@ try {
+     if (inStream.readLine() != null) {
+         String v = inStream.readLine();
+         if (v != null) {
+-            int ib = v.indexOf(" (build ");
++            int ib = v.indexOf(" (guix build ");
+             if (ib != -1) {
+-                String ver = v.substring(ib + 8, v.size() - 1);
++                String ver = v.substring(ib + 13, v.size() - 1);
+ 
+                 defineProperty("jdkRuntimeVersion", ver)
+                 defineProperty("jdkVersion", jdkRuntimeVersion.split("-")[0])
+@@ -3540,4 +3540,3 @@ compileTargets { t ->
+         }
+     )
+ }
+-
+-- 
+2.24.1
+
-- 
2.24.1