[flang] Fix references to destroyed objects (#111582)

ProgramTree instances are created as the value of a local variable in
the Pre(const parser::ProgramUnit &) member function in name resolution.
But references to these ProgramTree instances can persist in
SubprogramNameDetails symbol table entries that might survive that
function call's lifetime, and lead to trouble later when (e.g.)
expression semantics needs to deal with a possible forward reference in
a function reference in an expression being processed later in
expression checking.

So put those ProgramTree instances into a longer-lived linked list
within the SemanticsContext.

Might fix some weird crashes reported on big-endian targets (AIX &
Solaris).

0 files changed, 0 insertions, 0 deletions