[Issue 3276] Recursion broken by alias template parameter
https://issues.dlang.org/show_bug.cgi?id=3276 Andrei Alexandrescu and...@erdani.com changed: What|Removed |Added Version|2.032 |D2 --
[Issue 3276] Recursion broken by alias template parameter
http://d.puremagic.com/issues/show_bug.cgi?id=3276 Walter Bright bugzi...@digitalmars.com changed: What|Removed |Added Status|NEW |RESOLVED CC||bugzi...@digitalmars.com Resolution||FIXED --- Comment #4 from Walter Bright bugzi...@digitalmars.com 2010-12-05 23:00:13 PST --- http://www.dsource.org/projects/dmd/changeset/784 -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
Re: [Issue 3276] Recursion broken by alias template parameter
d-bugm...@puremagic.com wrote: http://d.puremagic.com/issues/show_bug.cgi?id=3276 --- Comment #3 from Shin Fujishiro rsi...@gmail.com 2010-11-02 22:11:39 PDT --- The patch passed dmd, druntime and phobos tests. It couldn't pass the broken test (runnable/interpret.d) though. What do you mean, the broken test? It needs to pass, unless you have modified the file from the one in svn. (It fails on Linux with -O, but that is not part of the test).
[Issue 3276] Recursion broken by alias template parameter
http://d.puremagic.com/issues/show_bug.cgi?id=3276
Shin Fujishiro rsi...@gmail.com changed:
What|Removed |Added
CC||rsi...@gmail.com
--- Comment #2 from Shin Fujishiro rsi...@gmail.com 2010-11-02 22:09:58 PDT
---
The bug happens if a recursive template is instantiated via an alias:
alias Bug3276 W;
alias W!true w;
In template.c, the following if at the line 4304 tries to get the relevant
TemplateDeclaration for doing recursion:
TemplateDeclaration *TemplateInstance::findTemplateDeclaration(Scope *sc)
{
...
TemplateInstance *ti;
if (s-parent
(ti = s-parent-isTemplateInstance()) != NULL)
{
if (
(ti-name == id ||
ti-toAlias()-ident == id)// -- the cause
ti-tempdecl)
...
}
Here 'this' refers to the recursive instantiation Bug3276!(false) and
id=Bug3276 is its identifier. 'ti' is the enclosing TemplateInstance (i.e.
W!(true)).
The test sees if the identifier 'id' used in the instantiation
Bug3276!(false) is the same as the one of enclosing 'ti'. But 'ti' was
instantiated with the aliased identifier (ti-name=W), so the first condition
isn't met.
Then it tests the next condition: ti-toAlias()-ident. It dives into the
following code in TemplateInstance::toAlias():
if (aliasdecl)
{
return aliasdecl-toAlias();
}
Here 'aliasdecl' is the result of the eponymous template Bug3276!(true),
and it's exactly the alias Bug3276!(false) analyzing now.
AliasDeclaration::toAlias() does the follownig check:
if (inSemantic)
{ error(recursive alias declaration);
aliassym = new TypedefDeclaration(loc, ident, Type::terror, NULL);
}
Since it's in semantic, the compiler raises the error.
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[Issue 3276] Recursion broken by alias template parameter
http://d.puremagic.com/issues/show_bug.cgi?id=3276
Shin Fujishiro rsi...@gmail.com changed:
What|Removed |Added
Keywords||patch
--- Comment #3 from Shin Fujishiro rsi...@gmail.com 2010-11-02 22:11:39 PDT
---
Patch against dmd r737.
--- src/template.c
+++ src/template.c
@@ -4304,11 +4304,7 @@ TemplateDeclaration
*TemplateInstance::findTemplateDeclaration(Scope *sc)
if (s-parent
(ti = s-parent-isTemplateInstance()) != NULL)
{
-if (
-(ti-name == id ||
- ti-toAlias()-ident == id)
-
-ti-tempdecl)
+if (ti-tempdecl ti-tempdecl-ident == id)
{
/* This is so that one can refer to the enclosing
* template, even if it has the same name as a member
Getting 'ti' for recognizing recursion is good; but the identifier should be
compared with the one of a TemplateDeclaration, not the TemplateInstance. As
happened in the reported bug, ti-name is not always the appropriate identifier
for recursion check.
The patch removes ti-toAlias() for good. TemplateInstance::toAlias() does
*not* resolve alias of itself; as seen in its implementation, it actually
returns the result of the template and makes no sense. 'id' has to be
compared with ti-tempdecl-ident.
The patch passed dmd, druntime and phobos tests. It couldn't pass the broken
test (runnable/interpret.d) though.
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[Issue 3276] Recursion broken by alias template parameter
http://d.puremagic.com/issues/show_bug.cgi?id=3276
Don clugd...@yahoo.com.au changed:
What|Removed |Added
Keywords||rejects-valid
CC||clugd...@yahoo.com.au
Summary|Mutual recursion broken in |Recursion broken by alias
|type templates |template parameter
--- Comment #1 from Don clugd...@yahoo.com.au 2010-05-12 12:35:28 PDT ---
Reduced test case shows it doesn't involve mutual recursion (original title was
Mutual recursion broken in type templates)
template Bug3276(bool B) {
static if (B)
alias Bug3276!(false) Bug3276;
else
alias double Bug3276;
}
template Bug3276_b(alias W) {
alias W!(true) Bug3276_b;
}
alias Bug3276_b!(Bug3276) Bug3276_c;
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