digitalmars.D.bugs - [Issue 2521] New: Not possible to return immutable value by ref
- d-bugmail puremagic.com (23/23) Dec 17 2008 http://d.puremagic.com/issues/show_bug.cgi?id=2521
- d-bugmail puremagic.com (14/14) Dec 17 2008 http://d.puremagic.com/issues/show_bug.cgi?id=2521
- d-bugmail puremagic.com (19/19) Dec 17 2008 http://d.puremagic.com/issues/show_bug.cgi?id=2521
- d-bugmail puremagic.com (8/8) Dec 18 2008 http://d.puremagic.com/issues/show_bug.cgi?id=2521
- d-bugmail puremagic.com (8/8) Dec 22 2008 http://d.puremagic.com/issues/show_bug.cgi?id=2521
- d-bugmail puremagic.com (35/35) Jun 07 2011 http://d.puremagic.com/issues/show_bug.cgi?id=2521
- d-bugmail puremagic.com (10/10) Jun 17 2011 http://d.puremagic.com/issues/show_bug.cgi?id=2521
- d-bugmail puremagic.com (12/12) Jun 30 2011 http://d.puremagic.com/issues/show_bug.cgi?id=2521
http://d.puremagic.com/issues/show_bug.cgi?id=2521 Summary: Not possible to return immutable value by ref Product: D Version: 2.022 Platform: PC OS/Version: Windows Status: NEW Severity: normal Priority: P2 Component: DMD AssignedTo: bugzilla digitalmars.com ReportedBy: aarti interia.pl module Test; immutable int val = 23; ref int func() { return val; } void main() { } ---- Result - compilation error: quicktest.d(3): Error: cast(int)23 is not an lvalue --
Dec 17 2008
http://d.puremagic.com/issues/show_bug.cgi?id=2521 2korden gmail.com changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Resolution| |INVALID Immutable variables are not lvalues, you can't take address of them because they might not present in a final executable. For example, everywhere you use val, it is replaced with 23. You can't return 23 by reference, can you? Besides, returning immutable values by mutable reference is disallowed: func() = 42; //what should this do if func() returns reference to immutable val? --
Dec 17 2008
http://d.puremagic.com/issues/show_bug.cgi?id=2521 torhu yahoo.com changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |torhu yahoo.com Status|RESOLVED |REOPENED Resolution|INVALID | From the docs (Const and Invariant page): "Invariant declarations can appear as lvalues, i.e. they can have their address taken, and occupy storage." This one works: immutable(int)* func() { return &val; } I assume that this is supposed to work too: ref immutable(int) func() { return val; } --
Dec 17 2008
http://d.puremagic.com/issues/show_bug.cgi?id=2521 I was not sure if this was supposed to work. But please notice that it is bug anyway as the line number in error message and message itself is totally misleading. It suggest that problem is with variable declaration, instead of with function. --
Dec 18 2008
http://d.puremagic.com/issues/show_bug.cgi?id=2521 This is definitely an invalid bug! Func has a return type of "ref int". The ref means that what gets returned by the function can be modified (and affect the underlying data used by func). If the return type of func was int, I would hope the code would compile, but that's a whole other issue... --
Dec 22 2008
http://d.puremagic.com/issues/show_bug.cgi?id=2521 yebblies <yebblies gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |patch, rejects-valid CC| |yebblies gmail.com This bug addresses two issues. This does not currently work: ------------------------------- immutable int val = 23; ref immutable(int) func() { return val; } Error: constant 23 is not an lvalue ------------------------------- And this gives the same terrible error message: ------------------------------- immutable int val = 23; ref int func() { return val; } Error: constant 23 is not an lvalue ------------------------------- The proposed fix (dmd pull 92) allows the first case, and changes the error to the following for the second case: Error: cast(int)val is not an lvalue The root cause of this bug is the fact that while running semantic on the return expression, the immutable variable's value is known at compile time, and is optimized without checking if the function returns an lvalue. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 07 2011
http://d.puremagic.com/issues/show_bug.cgi?id=2521 Kenji Hara <k.hara.pg gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |dsimcha yahoo.com *** Issue 2780 has been marked as a duplicate of this issue. *** -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 17 2011
http://d.puremagic.com/issues/show_bug.cgi?id=2521 Walter Bright <bugzilla digitalmars.com> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|REOPENED |RESOLVED CC| |bugzilla digitalmars.com Resolution| |FIXED 13:23:06 PDT --- https://github.com/D-Programming-Language/dmd/commit/099ed3c987c8cca5dbb8614e21b2a5de99a49252 -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 30 2011