From 44014fa1cdd2b39eaa4e1ef1ee6e2287870ad9fb Mon Sep 17 00:00:00 2001
From: Michael Ernst <mernst@cs.washington.edu>
Date: Sat, 10 Oct 2026 12:02:45 -0700
Subject: [PATCH 1/4] Factor JAVA_HOME detection into scripts/java-home.mak

Use ":=" so the shell commands run once, not on every expansion.
---
 Makefile                                |  2 +-
 java/Makefile                           | 12 +-----------
 scripts/java-home.mak                   | 16 ++++++++++++++++
 tests/Makefile.common                   | 12 +-----------
 tests/daikon-tests/junit/Makefile.user  | 12 +-----------
 tests/daikon-tests/junit5/Makefile.user | 12 +-----------
 6 files changed, 21 insertions(+), 45 deletions(-)
 create mode 100644 scripts/java-home.mak

diff --git a/Makefile b/Makefile
index 3783aa641d..36e6cfe1a3 100644
--- a/Makefile
+++ b/Makefile
@@ -59,7 +59,7 @@ DIST_VERSION_FILES := ${README_PATHS} doc/daikon.texinfo doc/developer.texinfo \
 # Need to include the Dockerfiles as they are referenced from 'Requirements for
 # compiling Daikon' in the Daikon Developer manual; which is in turn referenced
 # from the 'Installation' section of the Daikon manual.
-SCRIPT_FILES := Makefile \
+SCRIPT_FILES := Makefile java-home.mak \
 	daikon.bashrc \
 	dfepl dtrace-perl dtype-perl \
 	java-cpp \
diff --git a/java/Makefile b/java/Makefile
index ce436e5d69..4f152f2186 100644
--- a/java/Makefile
+++ b/java/Makefile
@@ -25,17 +25,7 @@ JAR ?= jar
 
 BuildJDKTool = BuildJDK
 
-ifeq ($(shell uname), Darwin)
-  JAVA_HOME ?= $(shell /usr/libexec/java_home)
-else
-ifeq ($(shell which javac > /dev/null 2>&1 && echo found || echo nonexistent), found)
-  JAVA_HOME ?= $(shell readlink -f $(shell which javac) | sed "s:/bin/javac::")
-else
-  $(info Failure: Here is the output of: which javac)
-  $(info $(shell which javac))
-  $(error 'which javac' had exit status 1)
-endif
-endif
+include ${DAIKONDIR}/scripts/java-home.mak
 
 # The "JAVANN" variables mean "at least version NN", except JAVA8.
 JAVA_VERSION_STRING_WITH_EA := $(shell javac -version 2>&1 | head -1 | cut "-d " -f2)
diff --git a/scripts/java-home.mak b/scripts/java-home.mak
new file mode 100644
index 0000000000..3d614faee8
--- /dev/null
+++ b/scripts/java-home.mak
@@ -0,0 +1,16 @@
+# Sets JAVA_HOME, if it is not already set.
+# Uses ":=" so that the shell commands run only once.
+
+ifndef JAVA_HOME
+ifeq ($(shell uname), Darwin)
+  JAVA_HOME := $(shell /usr/libexec/java_home)
+else
+ifeq ($(shell which javac > /dev/null 2>&1 && echo found || echo nonexistent), found)
+  JAVA_HOME := $(shell readlink -f $(shell which javac) | sed "s:/bin/javac::")
+else
+  $(info Failure: Here is the output of: which javac)
+  $(info $(shell which javac))
+  $(error 'which javac' had exit status 1)
+endif
+endif
+endif
diff --git a/tests/Makefile.common b/tests/Makefile.common
index 38dde8e8cb..661bab293e 100644
--- a/tests/Makefile.common
+++ b/tests/Makefile.common
@@ -186,17 +186,7 @@ ECLAT_SCRATCH = $(SCRATCH_FOR_DAIKON_BASE)/$(PROJECT)_eclat
 # CP_PARENTS := cp -pf --parents
 CP_PARENTS := rsync -aR
 
-ifeq ($(shell uname), Darwin)
-  JAVA_HOME ?= $(/usr/libexec/java_home)
-else
-ifeq ($(shell which javac > /dev/null 2>&1 && echo found || echo nonexistent), found)
-  JAVA_HOME ?= $(shell readlink -f $(shell which javac) | sed "s:/bin/javac::")
-else
-  $(info Failure: Here is the output of: which javac)
-  $(info $(shell which javac))
-  $(error 'which javac' had exit status 1)
-endif
-endif
+include ${DAIKONDIR}/scripts/java-home.mak
 JAVA  := ${JAVA_HOME}/bin/java
 JAVAC ?= ${JAVA_HOME}/bin/javac
 
diff --git a/tests/daikon-tests/junit/Makefile.user b/tests/daikon-tests/junit/Makefile.user
index 9c2889b925..487fe63617 100644
--- a/tests/daikon-tests/junit/Makefile.user
+++ b/tests/daikon-tests/junit/Makefile.user
@@ -1,16 +1,6 @@
 ###########################################################################
 
-ifeq ($(shell uname), Darwin)
-  JAVA_HOME ?= $(/usr/libexec/java_home)
-else
-ifeq ($(shell which javac > /dev/null 2>&1 && echo found || echo nonexistent), found)
-  JAVA_HOME ?= $(shell readlink -f $(shell which javac) | sed "s:/bin/javac::")
-else
-  $(info Failure: Here is the output of: which javac)
-  $(info $(shell which javac))
-  $(error 'which javac' had exit status 1)
-endif
-endif
+include ${DAIKONDIR}/scripts/java-home.mak
 
 # need junit.jar on classpath to compile all junit references
 JUNIT_CLASSPATH := ${DAIKONDIR}/java/lib/*
diff --git a/tests/daikon-tests/junit5/Makefile.user b/tests/daikon-tests/junit5/Makefile.user
index d10d1f57d7..08ccc10c01 100644
--- a/tests/daikon-tests/junit5/Makefile.user
+++ b/tests/daikon-tests/junit5/Makefile.user
@@ -1,16 +1,6 @@
 ###########################################################################
 
-ifeq ($(shell uname), Darwin)
-  JAVA_HOME ?= $(/usr/libexec/java_home)
-else
-ifeq ($(shell which javac > /dev/null 2>&1 && echo found || echo nonexistent), found)
-  JAVA_HOME ?= $(shell readlink -f $(shell which javac) | sed "s:/bin/javac::")
-else
-  $(info Failure: Here is the output of: which javac)
-  $(info $(shell which javac))
-  $(error 'which javac' had exit status 1)
-endif
-endif
+include ${DAIKONDIR}/scripts/java-home.mak
 
 # need junit.jar on classpath to compile all junit references
 # explicit order is necessary to get versions built with JDK 8 not 5

From 3a24a837ff67a15c714472c822679bf5c09b1423 Mon Sep 17 00:00:00 2001
From: Michael Ernst <mernst@cs.washington.edu>
Date: Sat, 10 Oct 2026 12:33:35 -0700
Subject: [PATCH 2/4] Address code review of java-home.mak

Check that javac is on the PATH even when JAVA_HOME is set, report a
failure of /usr/libexec/java_home, warn when JAVA_HOME disagrees with the
javac on the PATH, compute JAVA_HOME with Make built-ins, and export it.
Include the fragment once in tests/Makefile.common, relative to that file
rather than DAIKONDIR, and after the Makefile.user includes.

Co-Authored-By: Claude <noreply@anthropic.com>
---
 Makefile                                |  2 +-
 scripts/java-home.mak                   | 36 ++++++++++++++++---------
 tests/Makefile.common                   |  8 ++++--
 tests/daikon-tests/junit/Makefile.user  |  5 ++--
 tests/daikon-tests/junit5/Makefile.user |  5 ++--
 5 files changed, 35 insertions(+), 21 deletions(-)

diff --git a/Makefile b/Makefile
index 36e6cfe1a3..0449aa2ec7 100644
--- a/Makefile
+++ b/Makefile
@@ -454,7 +454,7 @@ staging:
 	@echo "]2;Building Javadoc"
 	mkdir ${STAGING_DIR}/download/api
 	# Javadoc is skipped on Java 8.  Hard-coded JAVA_HOME path is a hack.
-	(export PATH=/usr/lib/jvm/java-11/bin:${PATH}; cd java; ${MAKE} SKIP_JAVADOC=0 'JAVADOC_DEST=${STAGING_DIR}/download/api' javadoc)
+	(export JAVA_HOME=/usr/lib/jvm/java-11 PATH=/usr/lib/jvm/java-11/bin:${PATH}; cd java; ${MAKE} SKIP_JAVADOC=0 'JAVADOC_DEST=${STAGING_DIR}/download/api' javadoc)
 	# Copy the documentation
 	@echo "]2;Copying documentation"
 	mkdir ${STAGING_DIR}/download/doc
diff --git a/scripts/java-home.mak b/scripts/java-home.mak
index 3d614faee8..f43d1527b5 100644
--- a/scripts/java-home.mak
+++ b/scripts/java-home.mak
@@ -1,16 +1,28 @@
-# Sets JAVA_HOME, if it is not already set.
-# Uses ":=" so that the shell commands run only once.
+# Sets JAVA_HOME, if it is not already set, and exports it so that sub-makes
+# do not recompute it.  Requires javac to be on the PATH.
+
+JAVAC_ON_PATH := $(shell command -v javac 2>/dev/null)
+ifeq (,$(JAVAC_ON_PATH))
+  $(error javac is not on the PATH)
+endif
 
-ifndef JAVA_HOME
 ifeq ($(shell uname), Darwin)
-  JAVA_HOME := $(shell /usr/libexec/java_home)
-else
-ifeq ($(shell which javac > /dev/null 2>&1 && echo found || echo nonexistent), found)
-  JAVA_HOME := $(shell readlink -f $(shell which javac) | sed "s:/bin/javac::")
+  # On macOS, /usr/bin/javac is a stub that uses JAVA_HOME, so JAVA_HOME and
+  # the javac on the PATH always agree.
+  ifndef JAVA_HOME
+    JAVA_HOME := $(shell /usr/libexec/java_home)
+    ifeq (,$(JAVA_HOME))
+      $(error /usr/libexec/java_home did not find a JDK; set JAVA_HOME)
+    endif
+  endif
 else
-  $(info Failure: Here is the output of: which javac)
-  $(info $(shell which javac))
-  $(error 'which javac' had exit status 1)
-endif
-endif
+  # Resolve symbolic links such as /usr/bin/javac -> /etc/alternatives/javac.
+  JAVAC_ON_PATH_REALPATH := $(realpath $(JAVAC_ON_PATH))
+  ifndef JAVA_HOME
+    JAVA_HOME := $(patsubst %/bin/javac,%,$(JAVAC_ON_PATH_REALPATH))
+  else ifneq ($(realpath $(JAVA_HOME)/bin/javac),$(JAVAC_ON_PATH_REALPATH))
+    $(warning JAVA_HOME is $(JAVA_HOME), but the javac on the PATH is $(JAVAC_ON_PATH_REALPATH))
+  endif
 endif
+
+export JAVA_HOME
diff --git a/tests/Makefile.common b/tests/Makefile.common
index 661bab293e..84c35bee1d 100644
--- a/tests/Makefile.common
+++ b/tests/Makefile.common
@@ -133,12 +133,15 @@ ifdef ESC_ON
 endif
 
 
+# MAKEFILE_COMMON_DIR is the directory containing this file, even if the user set DAIKONDIR.
+MAKEFILE_COMMON_DIR := $(realpath $(dir $(lastword $(MAKEFILE_LIST))))
+
 # DAIKONDIR is the clone of the 'daikon' project.
 # Would like to use simple '?=' but this is recursively expanded while ':=' is simply expanded.
 # The include of Makefile.user (if it exists) will change the value of MAKEFILE_LIST and thus
 # '?=' will not evaluate as we desire.
 ifeq ($(origin DAIKONDIR), undefined)
-  DAIKONDIR := $(realpath $(dir $(lastword $(MAKEFILE_LIST)))..)
+  DAIKONDIR := $(realpath ${MAKEFILE_COMMON_DIR}/..)
 endif
 
 # COMMON_HERE is where the Makefile.common is located.
@@ -186,7 +189,8 @@ ECLAT_SCRATCH = $(SCRATCH_FOR_DAIKON_BASE)/$(PROJECT)_eclat
 # CP_PARENTS := cp -pf --parents
 CP_PARENTS := rsync -aR
 
-include ${DAIKONDIR}/scripts/java-home.mak
+# This follows the Makefile.user includes, so that a JAVA_HOME set there takes precedence.
+include ${MAKEFILE_COMMON_DIR}/../scripts/java-home.mak
 JAVA  := ${JAVA_HOME}/bin/java
 JAVAC ?= ${JAVA_HOME}/bin/javac
 
diff --git a/tests/daikon-tests/junit/Makefile.user b/tests/daikon-tests/junit/Makefile.user
index 487fe63617..7e277bae7a 100644
--- a/tests/daikon-tests/junit/Makefile.user
+++ b/tests/daikon-tests/junit/Makefile.user
@@ -1,7 +1,6 @@
 ###########################################################################
 
-include ${DAIKONDIR}/scripts/java-home.mak
-
 # need junit.jar on classpath to compile all junit references
 JUNIT_CLASSPATH := ${DAIKONDIR}/java/lib/*
-JAVAC := $(JAVA_HOME)/bin/javac -cp .:$(JUNIT_CLASSPATH)
+# "=" because Makefile.common sets JAVA_HOME after including this file.
+JAVAC = $(JAVA_HOME)/bin/javac -cp .:$(JUNIT_CLASSPATH)
diff --git a/tests/daikon-tests/junit5/Makefile.user b/tests/daikon-tests/junit5/Makefile.user
index 08ccc10c01..a15d1be4ff 100644
--- a/tests/daikon-tests/junit5/Makefile.user
+++ b/tests/daikon-tests/junit5/Makefile.user
@@ -1,8 +1,7 @@
 ###########################################################################
 
-include ${DAIKONDIR}/scripts/java-home.mak
-
 # need junit.jar on classpath to compile all junit references
 # explicit order is necessary to get versions built with JDK 8 not 5
 JUNIT_CLASSPATH := ${DAIKONDIR}/java/lib/junit-4.13.2-Daikon.jar:${DAIKONDIR}/java/lib/hamcrest-core-1.3-Daikon.jar:${DAIKONDIR}/java/lib/*
-JAVAC := $(JAVA_HOME)/bin/javac -cp .:$(JUNIT_CLASSPATH)
+# "=" because Makefile.common sets JAVA_HOME after including this file.
+JAVAC = $(JAVA_HOME)/bin/javac -cp .:$(JUNIT_CLASSPATH)

From 4ccfbbc341cad16036f5ed055ad636e6d1fce996 Mon Sep 17 00:00:00 2001
From: Michael Ernst <mernst@cs.washington.edu>
Date: Sat, 10 Oct 2026 12:47:02 -0700
Subject: [PATCH 3/4] Make java-home.mak stricter and simplify its clients

On macOS, use /usr/libexec/java_home only when the javac on the PATH is the
/usr/bin/javac stub; otherwise derive JAVA_HOME from the javac on the PATH.
Check that the derived JAVA_HOME contains bin/javac.  Make a mismatch between
JAVA_HOME and the javac on the PATH an error.  Do not export JAVA_HOME.
Simplify DAIKONDIR in tests/Makefile.common, and let Makefile.common add
JUNIT_CLASSPATH to JAVAC rather than redefining JAVAC in Makefile.user files.
---
 scripts/java-home.mak                   | 44 ++++++++++++++++---------
 tests/Makefile.common                   | 10 ++----
 tests/daikon-tests/junit/Makefile.user  |  2 --
 tests/daikon-tests/junit5/Makefile.user |  2 --
 4 files changed, 30 insertions(+), 28 deletions(-)

diff --git a/scripts/java-home.mak b/scripts/java-home.mak
index f43d1527b5..ef9e0a554f 100644
--- a/scripts/java-home.mak
+++ b/scripts/java-home.mak
@@ -1,28 +1,40 @@
-# Sets JAVA_HOME, if it is not already set, and exports it so that sub-makes
-# do not recompute it.  Requires javac to be on the PATH.
+# Sets JAVA_HOME, if it is not already set, to the JDK that contains the javac
+# on the PATH.  If JAVA_HOME is already set, checks that it agrees with the
+# javac on the PATH.  Requires javac to be on the PATH.
 
 JAVAC_ON_PATH := $(shell command -v javac 2>/dev/null)
 ifeq (,$(JAVAC_ON_PATH))
   $(error javac is not on the PATH)
 endif
+# Resolve symbolic links such as /usr/bin/javac -> /etc/alternatives/javac.
+JAVAC_ON_PATH_REALPATH := $(realpath $(JAVAC_ON_PATH))
 
+# On macOS, /usr/bin/javac is a stub that runs the javac of JAVA_HOME if it is
+# set, or else of the JDK that /usr/libexec/java_home reports.
+JAVAC_ON_PATH_IS_MACOS_STUB :=
 ifeq ($(shell uname), Darwin)
-  # On macOS, /usr/bin/javac is a stub that uses JAVA_HOME, so JAVA_HOME and
-  # the javac on the PATH always agree.
-  ifndef JAVA_HOME
-    JAVA_HOME := $(shell /usr/libexec/java_home)
+  ifeq ($(JAVAC_ON_PATH_REALPATH), /usr/bin/javac)
+    JAVAC_ON_PATH_IS_MACOS_STUB := 1
+  endif
+endif
+
+ifndef JAVA_HOME
+  ifdef JAVAC_ON_PATH_IS_MACOS_STUB
+    JAVA_HOME := $(shell /usr/libexec/java_home 2>/dev/null)
     ifeq (,$(JAVA_HOME))
-      $(error /usr/libexec/java_home did not find a JDK; set JAVA_HOME)
+      $(error /usr/libexec/java_home did not find a JDK; set JAVA_HOME or put a JDK's bin directory on the PATH)
     endif
-  endif
-else
-  # Resolve symbolic links such as /usr/bin/javac -> /etc/alternatives/javac.
-  JAVAC_ON_PATH_REALPATH := $(realpath $(JAVAC_ON_PATH))
-  ifndef JAVA_HOME
+  else
     JAVA_HOME := $(patsubst %/bin/javac,%,$(JAVAC_ON_PATH_REALPATH))
-  else ifneq ($(realpath $(JAVA_HOME)/bin/javac),$(JAVAC_ON_PATH_REALPATH))
-    $(warning JAVA_HOME is $(JAVA_HOME), but the javac on the PATH is $(JAVAC_ON_PATH_REALPATH))
+  endif
+  ifeq (,$(wildcard $(JAVA_HOME)/bin/javac))
+    $(error Cannot determine JAVA_HOME from $(JAVAC_ON_PATH) (which resolves to $(JAVAC_ON_PATH_REALPATH)); set JAVA_HOME)
+  endif
+else ifndef JAVAC_ON_PATH_IS_MACOS_STUB
+  # A javac that is not within a JDK, such as a jenv shim script, is not checked.
+  ifneq ($(filter %/bin/javac,$(JAVAC_ON_PATH_REALPATH)),)
+  ifneq ($(realpath $(JAVA_HOME)/bin/javac),$(JAVAC_ON_PATH_REALPATH))
+    $(error JAVA_HOME is $(JAVA_HOME), but the javac on the PATH is $(JAVAC_ON_PATH_REALPATH); make them agree)
+  endif
   endif
 endif
-
-export JAVA_HOME
diff --git a/tests/Makefile.common b/tests/Makefile.common
index 84c35bee1d..e8bdab9098 100644
--- a/tests/Makefile.common
+++ b/tests/Makefile.common
@@ -137,12 +137,7 @@ endif
 MAKEFILE_COMMON_DIR := $(realpath $(dir $(lastword $(MAKEFILE_LIST))))
 
 # DAIKONDIR is the clone of the 'daikon' project.
-# Would like to use simple '?=' but this is recursively expanded while ':=' is simply expanded.
-# The include of Makefile.user (if it exists) will change the value of MAKEFILE_LIST and thus
-# '?=' will not evaluate as we desire.
-ifeq ($(origin DAIKONDIR), undefined)
-  DAIKONDIR := $(realpath ${MAKEFILE_COMMON_DIR}/..)
-endif
+DAIKONDIR ?= $(realpath ${MAKEFILE_COMMON_DIR}/..)
 
 # COMMON_HERE is where the Makefile.common is located.
 COMMON_HERE?=${DAIKONDIR}/tests
@@ -192,9 +187,8 @@ CP_PARENTS := rsync -aR
 # This follows the Makefile.user includes, so that a JAVA_HOME set there takes precedence.
 include ${MAKEFILE_COMMON_DIR}/../scripts/java-home.mak
 JAVA  := ${JAVA_HOME}/bin/java
-JAVAC ?= ${JAVA_HOME}/bin/javac
-
 JUNIT_CLASSPATH ?=
+JAVAC ?= ${JAVA_HOME}/bin/javac$(if ${JUNIT_CLASSPATH}, -cp .:${JUNIT_CLASSPATH})
 
 JAVALIB_CLASSPATH := ${JAVA_HOME}/jre/lib/rt.jar:${JAVA_HOME}/lib/tools.jar
 
diff --git a/tests/daikon-tests/junit/Makefile.user b/tests/daikon-tests/junit/Makefile.user
index 7e277bae7a..c0917ab212 100644
--- a/tests/daikon-tests/junit/Makefile.user
+++ b/tests/daikon-tests/junit/Makefile.user
@@ -2,5 +2,3 @@
 
 # need junit.jar on classpath to compile all junit references
 JUNIT_CLASSPATH := ${DAIKONDIR}/java/lib/*
-# "=" because Makefile.common sets JAVA_HOME after including this file.
-JAVAC = $(JAVA_HOME)/bin/javac -cp .:$(JUNIT_CLASSPATH)
diff --git a/tests/daikon-tests/junit5/Makefile.user b/tests/daikon-tests/junit5/Makefile.user
index a15d1be4ff..8a61e160f6 100644
--- a/tests/daikon-tests/junit5/Makefile.user
+++ b/tests/daikon-tests/junit5/Makefile.user
@@ -3,5 +3,3 @@
 # need junit.jar on classpath to compile all junit references
 # explicit order is necessary to get versions built with JDK 8 not 5
 JUNIT_CLASSPATH := ${DAIKONDIR}/java/lib/junit-4.13.2-Daikon.jar:${DAIKONDIR}/java/lib/hamcrest-core-1.3-Daikon.jar:${DAIKONDIR}/java/lib/*
-# "=" because Makefile.common sets JAVA_HOME after including this file.
-JAVAC = $(JAVA_HOME)/bin/javac -cp .:$(JUNIT_CLASSPATH)

From f0dd11dd9dad1ca8cdddfb1b83e2b70bbc6397c0 Mon Sep 17 00:00:00 2001
From: Michael Ernst <mernst@cs.washington.edu>
Date: Sat, 10 Oct 2026 13:24:30 -0700
Subject: [PATCH 4/4] Address code review of PR 896

- daikon.bashrc uses the same PATH-first JAVA_HOME logic as java-home.mak.
- java-home.mak recognizes a JDK by its release file, so a javac wrapper
  is neither used to infer JAVA_HOME nor checked against it.
- java-home.mak reports a nonexistent JAVA_HOME and paths with whitespace.
- The staging target sets JAVA_HOME only if /usr/lib/jvm/java-11 exists.
- JUnit tests use JUNIT_CLASSPATH even if JAVAC is set in the environment.
- tests/Makefile.common includes java-home.mak via DAIKONDIR.
---
 Makefile              |  2 +-
 scripts/daikon.bashrc | 16 ++++++++++++----
 scripts/java-home.mak | 37 +++++++++++++++++++++++++++++--------
 tests/Makefile.common |  9 +++++++--
 4 files changed, 49 insertions(+), 15 deletions(-)

diff --git a/Makefile b/Makefile
index 0449aa2ec7..1e7a12d0b4 100644
--- a/Makefile
+++ b/Makefile
@@ -454,7 +454,7 @@ staging:
 	@echo "]2;Building Javadoc"
 	mkdir ${STAGING_DIR}/download/api
 	# Javadoc is skipped on Java 8.  Hard-coded JAVA_HOME path is a hack.
-	(export JAVA_HOME=/usr/lib/jvm/java-11 PATH=/usr/lib/jvm/java-11/bin:${PATH}; cd java; ${MAKE} SKIP_JAVADOC=0 'JAVADOC_DEST=${STAGING_DIR}/download/api' javadoc)
+	(if [ -d /usr/lib/jvm/java-11 ]; then export JAVA_HOME=/usr/lib/jvm/java-11 PATH=/usr/lib/jvm/java-11/bin:$${PATH}; fi; cd java; ${MAKE} SKIP_JAVADOC=0 'JAVADOC_DEST=${STAGING_DIR}/download/api' javadoc)
 	# Copy the documentation
 	@echo "]2;Copying documentation"
 	mkdir ${STAGING_DIR}/download/doc
diff --git a/scripts/daikon.bashrc b/scripts/daikon.bashrc
index 9949bdde44..6ef2d27bed 100644
--- a/scripts/daikon.bashrc
+++ b/scripts/daikon.bashrc
@@ -8,10 +8,18 @@
 ##        files to .class files but have not re-made the daikon.jar file.
 ## You should not need to edit this file.
 
-if [ "$(uname)" = "Darwin" ] ; then
-  export JAVA_HOME=${JAVA_HOME:-$(/usr/libexec/java_home)}
-else
-  export JAVA_HOME=${JAVA_HOME:-$(dirname $(dirname $(readlink -f $(which javac))))}
+# This logic is the same as in java-home.mak:  use the JDK that contains the
+# javac on the PATH.  On macOS, /usr/bin/javac is a stub; then use the JDK that
+# /usr/libexec/java_home reports.
+if [ -z "$JAVA_HOME" ] ; then
+  DAIKON_JAVAC_REALPATH=$(type -P javac > /dev/null && readlink -f "$(type -P javac)")
+  if [ "$(uname)" = "Darwin" ] && [ "$DAIKON_JAVAC_REALPATH" = "/usr/bin/javac" ] ; then
+    JAVA_HOME=$(/usr/libexec/java_home)
+  elif [ -n "$DAIKON_JAVAC_REALPATH" ] ; then
+    JAVA_HOME=$(dirname "$(dirname "$DAIKON_JAVAC_REALPATH")")
+  fi
+  unset DAIKON_JAVAC_REALPATH
+  export JAVA_HOME
 fi
 if [ ! -d "$JAVA_HOME" ]; then
   echo "Cannot infer JAVA_HOME; please set it.  Aborting daikon.bashrc ."
diff --git a/scripts/java-home.mak b/scripts/java-home.mak
index ef9e0a554f..a6aeb1af98 100644
--- a/scripts/java-home.mak
+++ b/scripts/java-home.mak
@@ -1,11 +1,16 @@
 # Sets JAVA_HOME, if it is not already set, to the JDK that contains the javac
 # on the PATH.  If JAVA_HOME is already set, checks that it agrees with the
 # javac on the PATH.  Requires javac to be on the PATH.
+# A JDK is recognized by its "release" file.
+# Paths that contain whitespace are not supported, because Make splits on it.
 
 JAVAC_ON_PATH := $(shell command -v javac 2>/dev/null)
 ifeq (,$(JAVAC_ON_PATH))
   $(error javac is not on the PATH)
 endif
+ifneq (1,$(words $(JAVAC_ON_PATH)))
+  $(error The javac on the PATH, "$(JAVAC_ON_PATH)", contains whitespace, which is not supported)
+endif
 # Resolve symbolic links such as /usr/bin/javac -> /etc/alternatives/javac.
 JAVAC_ON_PATH_REALPATH := $(realpath $(JAVAC_ON_PATH))
 
@@ -18,23 +23,39 @@ ifeq ($(shell uname), Darwin)
   endif
 endif
 
+# The JDK that contains the javac on the PATH, or empty if that javac is not
+# within a JDK (for example, it is a wrapper script or a jenv shim).
+JAVAC_ON_PATH_JDK :=
+ifndef JAVAC_ON_PATH_IS_MACOS_STUB
+  ifneq (,$(filter %/bin/javac,$(JAVAC_ON_PATH_REALPATH)))
+    ifneq (,$(wildcard $(patsubst %/bin/javac,%,$(JAVAC_ON_PATH_REALPATH))/release))
+      JAVAC_ON_PATH_JDK := $(patsubst %/bin/javac,%,$(JAVAC_ON_PATH_REALPATH))
+    endif
+  endif
+endif
+
 ifndef JAVA_HOME
   ifdef JAVAC_ON_PATH_IS_MACOS_STUB
     JAVA_HOME := $(shell /usr/libexec/java_home 2>/dev/null)
     ifeq (,$(JAVA_HOME))
       $(error /usr/libexec/java_home did not find a JDK; set JAVA_HOME or put a JDK's bin directory on the PATH)
     endif
+  else ifdef JAVAC_ON_PATH_JDK
+    JAVA_HOME := $(JAVAC_ON_PATH_JDK)
   else
-    JAVA_HOME := $(patsubst %/bin/javac,%,$(JAVAC_ON_PATH_REALPATH))
+    $(error Cannot determine JAVA_HOME: $(JAVAC_ON_PATH) (which resolves to $(JAVAC_ON_PATH_REALPATH)) is not within a JDK; set JAVA_HOME)
   endif
-  ifeq (,$(wildcard $(JAVA_HOME)/bin/javac))
-    $(error Cannot determine JAVA_HOME from $(JAVAC_ON_PATH) (which resolves to $(JAVAC_ON_PATH_REALPATH)); set JAVA_HOME)
+else
+  ifneq (1,$(words $(JAVA_HOME)))
+    $(error JAVA_HOME, "$(JAVA_HOME)", contains whitespace, which is not supported)
   endif
-else ifndef JAVAC_ON_PATH_IS_MACOS_STUB
-  # A javac that is not within a JDK, such as a jenv shim script, is not checked.
-  ifneq ($(filter %/bin/javac,$(JAVAC_ON_PATH_REALPATH)),)
-  ifneq ($(realpath $(JAVA_HOME)/bin/javac),$(JAVAC_ON_PATH_REALPATH))
-    $(error JAVA_HOME is $(JAVA_HOME), but the javac on the PATH is $(JAVAC_ON_PATH_REALPATH); make them agree)
+  ifeq (,$(wildcard $(JAVA_HOME)/bin/javac))
+    $(error JAVA_HOME is $(JAVA_HOME), but $(JAVA_HOME)/bin/javac does not exist)
   endif
+  # A javac that is not within a JDK is not checked.
+  ifdef JAVAC_ON_PATH_JDK
+    ifneq ($(realpath $(JAVA_HOME)/bin/javac),$(JAVAC_ON_PATH_REALPATH))
+      $(error JAVA_HOME is $(JAVA_HOME), but the javac on the PATH is $(JAVAC_ON_PATH_REALPATH); make them agree)
+    endif
   endif
 endif
diff --git a/tests/Makefile.common b/tests/Makefile.common
index e8bdab9098..ba9216ad45 100644
--- a/tests/Makefile.common
+++ b/tests/Makefile.common
@@ -185,10 +185,15 @@ ECLAT_SCRATCH = $(SCRATCH_FOR_DAIKON_BASE)/$(PROJECT)_eclat
 CP_PARENTS := rsync -aR
 
 # This follows the Makefile.user includes, so that a JAVA_HOME set there takes precedence.
-include ${MAKEFILE_COMMON_DIR}/../scripts/java-home.mak
+include ${DAIKONDIR}/scripts/java-home.mak
 JAVA  := ${JAVA_HOME}/bin/java
 JUNIT_CLASSPATH ?=
-JAVAC ?= ${JAVA_HOME}/bin/javac$(if ${JUNIT_CLASSPATH}, -cp .:${JUNIT_CLASSPATH})
+ifneq (,${JUNIT_CLASSPATH})
+  # The JUnit tests require JUNIT_CLASSPATH, even if the environment sets JAVAC.
+  JAVAC := ${JAVA_HOME}/bin/javac -cp .:${JUNIT_CLASSPATH}
+else
+  JAVAC ?= ${JAVA_HOME}/bin/javac
+endif
 
 JAVALIB_CLASSPATH := ${JAVA_HOME}/jre/lib/rt.jar:${JAVA_HOME}/lib/tools.jar