Forcing a compile time error of a JDK class by inserting some bad code is just ignored and the build continues, and appears to complete successfully.

Example:

# Running javac: 18 files; in /export2/Users/chris/repos/jdk8/tl/buildFail/make/com/sun/net/ssl
/java/re/jdk/1.8.0/promoted/latest/binaries/solaris-i586/bin/javac -J-XX:ThreadStackSize=768 -J-XX:-PrintVMOptions -J-XX:+UnlockDiagnosticVMOptions -J-XX:-LogVMOutput -J-client -J-Xmx512m -J-Xms512m -J-XX:PermSize=32m -J-XX:MaxPermSize=160m -g -Werror -Xlint:all,-deprecation -Xlint:all -Xlint:-path -source 7 -target 7 -encoding ascii -Xbootclasspath:../../../../../build/solaris-i586/classes -sourcepath ../../../../../src/closed/solaris/classes:../../../../../src/closed/share/classes:../../../../../build/solaris-i586/gensrc:../../../../../src/solaris/classes:../../../../../src/share/classes -d ../../../../../build/solaris-i586/classes @../../../../../build/solaris-i586/tmp/sun/com.sun.net.ssl/.classes.list.filtered
../../../../../src/share/classes/sun/net/www/protocol/http/HttpURLConnection.java:438: error: missing return statement
    }
    ^
Note: Some input files use or override a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
1 error
# javac finished
make381[3]: Leaving directory `/export2/Users/chris/repos/jdk8/tl/buildFail/make/com/sun/net/ssl'
make381[3]: Entering directory `/export2/Users/chris/repos/jdk8/tl/buildFail/make/com/sun/jarsigner'
make381[3]: Leaving directory `/export2/Users/chris/repos/jdk8/tl/buildFail/make/com/sun/jarsigner'
make381[3]: Entering directory `/export2/Users/chris/repos/jdk8/tl/buildFail/make/com/sun/image'