JDK-6888954 : argument formatting for assert() and friends
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: runtime
  • Affected Version: hs17
  • Priority: P4
  • Status: Closed
  • Resolution: Fixed
  • OS: generic
  • CPU: generic
  • Submitted: 2009-10-07
  • Updated: 2012-10-13
  • Resolved: 2010-05-18
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JDK 6 JDK 7 Other
6u21pFixed 7Fixed hs18Fixed
Related Reports
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JDK-6956472 - test/runtime/6888954/vmerrors.sh uses ksh-specific syntax
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JDK-6951923 - some uses of fatal1 were missed by 6888954
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JDK-6888953 - some calls to function-like macros are missing semicolons
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JDK-6949301 - G1: extend asserts / guarantees with format strings
Description
The HotSpot assert(), guarantee(), etc., macros require a message argument which is printed if the condition does not hold, e.g.:

   assert(referent->is_oop(), "bad referent");

As currently implemented the message must be a string literal.  It would be much more useful if multiple arguments could be used with format strings to provide more information, e.g.:

   assert(referent->is_oop(), "bad referent %p", referent);
Comments
SUGGESTED FIX Attached as assert-args.patch.zip.
29-04-2010
EVALUATION http://hg.openjdk.java.net/jdk7/hotspot-gc/hotspot/rev/f03d0a26bf83
29-04-2010
EVALUATION The easiest solution, variadic macros from C99, is not an option for HotSpot because they are not supported by Visual Studio 2003 which is used for Windows jdk6 builds. Could instead use a c++ temporary object to format the arguments and return the result via an operator const char*. Sample usage would be: assert(referent->is_oop(), err_msg("bad referent %p", referent)); where err_msg() constructs a temporary object with an internal buffer and formats the arguments. This allows existing, non-formatted asserts to remain unchanged and eliminates the need for numbered macros (assert1, assert2, etc.).
07-10-2009