digitalmars.D.bugs - [Issue 3162] New: can't fully use floats computed in CTFE as template parameters
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http://d.puremagic.com/issues/show_bug.cgi?id=3162
Summary: can't fully use floats computed in CTFE as template
parameters
Product: D
Version: 2.028
Platform: Other
OS/Version: Linux
Status: NEW
Keywords: rejects-valid
Severity: major
Priority: P2
Component: DMD
AssignedTo: nobody puremagic.com
ReportedBy: baryluk smp.if.uj.edu.pl
/** Computes square root at compile time */
real ctfe_sqrt(real x) {
real root = x / 2.0;
for (int ntries = 0; ntries < 10; ntries++) {
if (root * root - x == 0)
break;
root = (root + x / root) / 2.0;
}
return root;
}
/** Square root of 2 */
static const double sqrt2 = ctfe_sqrt(2.0);
import std.metastrings;
pragma(msg, Format!("s=", cast(int)(1000*sqrt2))); // works
pragma(msg, Format!("s=", cast(int)(1000*sqrt2), " ", cast(int)(1000*sqrt2), "
")); // doesn't work
//pragma(msg, Format!("s=", cast(int)(1000*sqrt2))); // also doesn't work
pragma(msg, Format!("s=", cast(int)((1.0+sqrt2/2.0))); // doesn't works
Looks that only first occurence of value derived from constant derived using
ctfs can be used.
It was working in some older releases.
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Jul 10 2009
d-bugmail puremagic.com http://d.puremagic.com/issues/show_bug.cgi?id=3162 07:34:37 PDT --- s=1414 /home/baryluk/ProjektyZSempa/D/onpd/onp/../onp/utils/misc.d(187): Error: expression cast(int)(1000 * sqrt2) is not a valid template value argument /home/baryluk/ProjektyZSempa/D/onpd/onp/../onp/utils/misc.d(187): Error: expression cast(int)(1000 * sqrt2) is not a valid template value argument /home/baryluk/ProjektyZSempa/D/onpd/onp/../onp/utils/misc.d(186): Error: expression cast(int)(1000 * (1 + sqrt2 / 2)) is not a valid template value argument ... -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jul 10 2009
http://d.puremagic.com/issues/show_bug.cgi?id=3162 07:48:34 PDT --- Created an attachment (id=420) --> (http://d.puremagic.com/issues/attachment.cgi?id=420) Source code which should compile Test case -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jul 10 2009
http://d.puremagic.com/issues/show_bug.cgi?id=3162
08:07:07 PDT ---
Simpler example
/** Square root of 2 */
static const double sqrt2 = ctfe_sqrt(2.0);
template X(E ...) { alias E X; }
//alias X!(sqrt2/1.0, sqrt2/2.0) X2; // doesn't work
//alias X!(sqrt2*sqrt2) X3; // doesn't work
static const double sqrt22 = sqrt2*sqrt2;
//alias X!(sqrt22) X4; // doesn't work
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Jul 10 2009
http://d.puremagic.com/issues/show_bug.cgi?id=3162
08:15:21 PDT ---
Additionally if i omit "double" in "static const double", it compiles! It is
the same type!
I was also testing this ctfe function
T i(T)(T x) {
return x;
}
and only with T=float,double,real i got errors.
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Jul 10 2009
http://d.puremagic.com/issues/show_bug.cgi?id=3162
Don <clugdbug yahoo.com.au> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |patch
CC| |clugdbug yahoo.com.au
Platform|Other |All
Summary|can't fully use floats |can't fully use
|computed in CTFE as |compile-time floats as
|template parameters |template parameters
OS/Version|Linux |All
Reduced test case shows it doesn't require CTFE:
-----
enum float one = 1 * 1;
template X(float E) { int X = 2; }
alias X!(one * one) X3;
----
This is really complicated, and took me ages to track down.
First problem is in declaration.c, near the end of VarDeclaration::semantic().
It calculates the value of the manifest constant, but discards the result
unless
it was an int or a string! That's a waste, since it was successfully
calculated.
In optimize.c expandVar() copys the exprInitializer and semantically analyzes
it, but it doesn't change the exprInitializer. So ei->type remains null the
next time expandVar is called for that same variable.
And since expandVar sets v->scope to NULL, it never gets another chance to
evaluate it.
So in optimize.c line 92, it bypasses the call to e = ei->copy(), returning
NULL from the function.
--> it cannot be evaluated at compile time.
The final patch is tiny: add floating point variables to the list of values
which get saved.
// line 1150 declaration.c || e->op==TOKfloat64
e = e->optimize(WANTvalue | WANTinterpret);
else
e = e->optimize(WANTvalue);
- if (e->op == TOKint64 || e->op == TOKstring)
+ if (e->op == TOKint64 || e->op == TOKstring || e->op==TOKfloat64)
{
ei->exp = e; // no errors, keep result
}
However, I think the logic in expandVar() is probably also wrong.
The bug can also be fixed by adding this line in optimize.c, line 89:
e = e->semantic(v->scope);
e = e->implicitCastTo(v->scope, v->type);
+ ei->type = e->type;
v->scope = NULL;
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Jul 13 2009
http://d.puremagic.com/issues/show_bug.cgi?id=3162
Walter Bright <bugzilla digitalmars.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
CC| |bugzilla digitalmars.com
Resolution| |FIXED
13:40:51 PDT ---
Fixed dmd 2.032
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Sep 03 2009