• no where.com Apr 23 2005
• zwang <nehzgnaw gmail.com> Apr 23 2005
• no where.com Apr 23 2005
• Thomas Kuehne <thomas-dloop kuehne.thisisspam.cn> Apr 24 2005

no where.com writes:

$ cat a.d

template T(int N) {
int[N] array;
}

const int x = 2;
const int y = x * x;

mixin T!(y);


$ dmd -c a.d
a.d(9): Integer constant expression expected instead of x * x

Since y is decl-ed as const, its value is known at compile time.

zwang <nehzgnaw gmail.com> writes:

no where.com wrote:
 $ cat a.d
 
 template T(int N) {
 int[N] array;
 }
 
 const int x = 2;
 const int y = x * x;
 
 mixin T!(y);
 
 
 $ dmd -c a.d
 a.d(9): Integer constant expression expected instead of x * x
 
 Since y is decl-ed as const, its value is known at compile time.
 
 


Although constant propagation and constant folding are nice,
yet I don't think it is a bug if the compiler misses some
optimizing opportunities.

Consider an extreme case:
const double x = cast(double)rand();
const double y = cos(x)*cos(x)+sin(x)*sin(x);
y is obviously 1.0, but it's not that obvious to all the compilers
I have used.

no where.com writes:

$ cat a.d

template T(int N) {
int[N] array;
}

const int x = 2;
const int y = x * x;

int[y] why_here_it_works;
//mixin T!(y);

$ dmd -c a.d
$ ls a.o
a.o



In article <d4f8uv$16q$1 digitaldaemon.com>, zwang says...
no where.com wrote:
 $ cat a.d
 
 template T(int N) {
 int[N] array;
 }
 
 const int x = 2;
 const int y = x * x;
 
 mixin T!(y);
 
 
 $ dmd -c a.d
 a.d(9): Integer constant expression expected instead of x * x
 
 Since y is decl-ed as const, its value is known at compile time.
 
 


Although constant propagation and constant folding are nice,
yet I don't think it is a bug if the compiler misses some
optimizing opportunities.

Consider an extreme case:
const double x = cast(double)rand();
const double y = cos(x)*cos(x)+sin(x)*sin(x);
y is obviously 1.0, but it's not that obvious to all the compilers
I have used.

Thomas Kuehne <thomas-dloop kuehne.thisisspam.cn> writes:

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no where.com schrieb am Sun, 24 Apr 2005 02:40:15 +0000 (UTC):
 $ cat a.d

 template T(int N) {
 int[N] array;
 }

 const int x = 2;
 const int y = x * x;

 mixin T!(y);


 $ dmd -c a.d
 a.d(9): Integer constant expression expected instead of x * x

 Since y is decl-ed as const, its value is known at compile time.


Added to DStress as
http://dstress.kuehne.cn/run/const_18.d
http://dstress.kuehne.cn/run/const_19.d

Thomas


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