This led to crashes as the line number cache would report a bogus line number
for a line of code, and we'd try to find a nonexistent column within the line
when printing diagnostics.
llvm-svn: 309503
When a diagnostic includes a highlighted range spanning multiple lines, clang
now supports printing out multiple lines of context if necessary to show the
highlighted ranges. This is not yet exposed in the driver, but can be enabled
by "-Xclang -fcaret-diagnostics-max-lines -Xclang N".
This is experimental until we can find out whether it works well in practice,
and if so, what a good default for the maximum number of lines is.
llvm-svn: 303589
Richard Smith