Hello, when compiling jdk/jdk on Windows, (with VS2017 update level 15.8 and not disabling warnings as errors ) I came across this warning leading to build error :
C:/jdk-just-clone/src/hotspot/share/runtime/flags/jvmFlagRangeList.cpp(341): error C2220: warning treated as error - no 'object' file generated C:/jdk-just-clone/src/hotspot/share/runtime/flags/jvmFlagRangeList.cpp(341): warning C4305: 'argument': truncation from 'const intx' to 'double' Would have been helpful to have a compiler flag set that really ***shows the code*** leading to the warning/error (because it comes from heavy macro expansion). The following CR , Reported by ralf.schmel...@sap.com<mailto:ralf.schmel...@sap.com> , fixes the issue : The flag -XX:EpsilonTLABElasticity (epsilon_globals.hpp, line 77) expects a double value, but uses max_intx in the allowed range. This leads to a truncation warning in the Windows build. If the value should only be guaranteed to be >= 1, then DBL_MAX should have been used instead. Webrev/bug : http://cr.openjdk.java.net/~mbaesken/webrevs/8209942/ https://bugs.openjdk.java.net/browse/JDK-8209942 Please review . Thanks, Matthias
