public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "ludovic at ludovic-brenta dot org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug ada/30740] Improper semantics in gnat's compilation of certain expressions involving modular arithmetic Date: Fri, 09 Feb 2007 14:34:00 -0000 [thread overview] Message-ID: <20070209143412.30576.qmail@sourceware.org> (raw) In-Reply-To: <bug-30740-14071@http.gcc.gnu.org/bugzilla/> ------- Comment #1 from ludovic at ludovic-brenta dot org 2007-02-09 14:34 ------- Shorter test case that reproduces the problem. with Ada.Text_IO; procedure test1 is type T1 is mod 9; package T1_IO is new Ada.Text_IO.Modular_IO(T1); X: T1 := 8; J1: constant := 5; begin for J2 in 5..5 loop pragma assert(X*(2**J1) = X*(2**J2)); if X*(2**J1) /= X*(2**J2) then Ada.Text_IO.Put_Line("Failed"); T1_IO.Put(X*(2**J1)); T1_IO.Put(X*(2**J2)); Ada.Text_IO.New_Line; end if; end loop; end test1; prints: Failed 4 0 To reproduce: gnatmake test1 To reproduce with correct behaviour (no output): gnatmake -gnato test1 Notice that when multiplying by 2**J1, the result is always correct because J2 is a named number and the calculation is done at compile time with the correct semantics. In contrast, J2 is non-static and exhibits the wrong semantics unless we add -gnato. Problem reproduced with GCC 4.1.1 but it's been there ever since 3.15p or even before. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30740
next prev parent reply other threads:[~2007-02-09 14:34 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2007-02-09 0:53 [Bug ada/30740] New: " jaffem at erau dot edu 2007-02-09 14:34 ` ludovic at ludovic-brenta dot org [this message] 2007-02-10 0:22 ` [Bug ada/30740] " jaffem at erau dot edu 2007-11-25 14:26 ` sam at gcc dot gnu dot org 2008-05-20 12:39 ` charlet at gcc dot gnu dot org 2008-05-20 12:46 ` charlet at gcc dot gnu dot org 2008-05-20 13:08 ` charlet at gcc dot gnu dot org 2008-05-20 20:26 ` sam at gcc dot gnu dot org
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20070209143412.30576.qmail@sourceware.org \ --to=gcc-bugzilla@gcc.gnu.org \ --cc=gcc-bugs@gcc.gnu.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).