[Bug ada/84142] New: Implicit_Dereference with Generic Formal Incomplete Types

[jhb.chat at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84142

            Bug ID: 84142
           Summary: Implicit_Dereference with Generic Formal Incomplete
                    Types
           Product: gcc
           Version: 7.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: ada
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jhb.chat at gmail dot com
  Target Milestone: ---
              Host: Windows 10 mingw64 from MSYS2
            Target: x86_64-w64-mingw32

I've found a few different ways to crash GNAT using the Implicit_Dereference
aspect coupled with generic formal incomplete types.  I've attached 3 different
projects that all cause a GNAT crash.  It is important to note that the first
one (Implicit_Dereference1) does NOT cause GNAT GPL 2017 to crash while the
remaining two projects do crash GNAT GPL 2017.  That might indicate that it is
a different bug for the first project.  A typical crash on GNAT 7.2.0 (FSF)
results in text similar to:

$ gprbuild default.gpr
gcc -c -gnato -gnatE -fstack-check -gnat12 main.adb
+===========================GNAT BUG DETECTED==============================+
| 7.2.0 (x86_64-w64-mingw32) Segmentation fault                            |
| Error detected at main.adb:56:9                                          |
| Please submit a bug report; see https://gcc.gnu.org/bugs/ .              |
| Use a subject line meaningful to you and us to track the bug.            |
| Include the entire contents of this bug box in the report.               |
| Include the exact command that you entered.                              |
| Also include sources listed below.                                       |
+==========================================================================+

Please include these source files with error report
Note that list may not be accurate in some cases,
so please double check that the problem can still
be reproduced with the set of files listed.
Consider also -gnatd.n switch (see debug.adb).

.\Implicit_Dereference3\src\main.adb

compilation abandoned
gprbuild: *** compilation phase failed

Just for comparison sake, I am also providing the GNAT GPL crash report as it
lists it as a different type of crash (which may help hint to the FSF version's
problem).  The GNAT GPL 2017 report is as follows:

Compile
   [Ada]          main.adb
+===========================GNAT BUG DETECTED==============================+
| GPL 2017 (20170515-63) (i686-pc-mingw32) Program_Error
EXCEPTION_ACCESS_VIOLATION|
| Error detected at s-stoele.adb:36:20                                     |
| Please submit a bug report by email to report@adacore.com.               |
| GAP members can alternatively use GNAT Tracker:                          |
| http://www.adacore.com/ section 'send a report'.                         |
| See gnatinfo.txt for full info on procedure for submitting bugs.         |
| Use a subject line meaningful to you and us to track the bug.            |
| Include the entire contents of this bug box in the report.               |
| Include the exact command that you entered.                              |
| Also include sources listed below.                                       |
| Use plain ASCII or MIME attachment(s).                                   |
+==========================================================================+

Please include these source files with error report
Note that list may not be accurate in some cases,
so please double check that the problem can still
be reproduced with the set of files listed.
Consider also -gnatd.n switch (see debug.adb).

.\Implicit_Dereference3\src\main.adb

compilation abandoned
gprbuild: *** compilation phase failed
[2018-01-30 20:31:25] process exited with status 4, elapsed time: 01.85s