digitalmars.D.learn - Inferred attributes errors in template function.
- vit (47/47) May 27 2022 Hello, I have this problem:
- user1234 (3/24) May 27 2022 on a side note that's funny how dmd manages to systematically
- user1234 (5/8) May 27 2022 They are actually correct, I dont know why at some point I
- Tejas (25/72) May 27 2022 Use `-verrors=context` for dmd
- Paul Backus (5/18) May 27 2022 No, there is nothing like this, at least not yet. It's being
Hello, I have this problem:
```d
static int i;
void bar(T)(){
static if(is(T == int))
(() system => 1)();
static if(is(T == float))
i = 42;
}
void foo(T)(){
bar!T();
}
void main() safe pure{
foo!long();
foo!float(); //Error: `pure` function `D main` cannot call
impure function `onlineapp.foo!float.foo`
foo!int(); //Error: ` safe` function `D main` cannot call
` system` function `onlineapp.foo!int.foo`
}
```
When template function foo is called and its inferred attributes
are not compatible with attributes of main, errors are not really
useful. Compiler print that foo!float is not pure or foo!int is
not safe but doesn't tell why. Is in dmd some flag that print
errors similarly to this?:
```d
void main() safe pure{
foo!long();
foo!float();
//Error: `pure` function `D main` cannot call impure
function `onlineapp.foo!float.foo`
//Error: potentially `pure` function
`onlineapp.foo!float.foo` cannot call impure function
`onlineapp.bar!float.bar`
//Error: potentially `pure` function
`onlineapp.bar!float.bar` cannot access mutable static data `i`
foo!int();
//Error: ` safe` function `D main` cannot call ` system`
function `onlineapp.foo!int.foo`
//Error: potentially ` safe` function
`onlineapp.foo!int.foo` cannot call ` system` function
`onlineapp.bar!int.bar`
//Error: potentially ` safe` function
`onlineapp.bar!int.bar` cannot call ` system` delegate
`onlineapp.bar!int.bar.__lambda1`
}
```
May 27 2022
On Friday, 27 May 2022 at 08:39:08 UTC, vit wrote:
Hello, I have this problem:
```d
static int i;
void bar(T)(){
static if(is(T == int))
(() system => 1)();
static if(is(T == float))
i = 42;
}
void foo(T)(){
bar!T();
}
void main() safe pure{
foo!long();
foo!float(); //Error: `pure` function `D main` cannot call
impure function `onlineapp.foo!float.foo`
foo!int(); //Error: ` safe` function `D main` cannot call
` system` function `onlineapp.foo!int.foo`
}
```
[...]
on a side note that's funny how dmd manages to systematically
print the less interesting message in both case.
May 27 2022
user1234 <user1234 12.de> On Friday, 27 May 2022 at 09:41:32 UTC, user1234 wrote:They are actually correct, I dont know why at some point I thought there was a problem. For the float one it's oviously not pure and for the int one it's not safe... OP wants better error message.[...]on a side note that's funny how dmd manages to systematically print the less interesting message in both case.
May 27 2022
On Friday, 27 May 2022 at 08:39:08 UTC, vit wrote:
Hello, I have this problem:
```d
static int i;
void bar(T)(){
static if(is(T == int))
(() system => 1)();
static if(is(T == float))
i = 42;
}
void foo(T)(){
bar!T();
}
void main() safe pure{
foo!long();
foo!float(); //Error: `pure` function `D main` cannot call
impure function `onlineapp.foo!float.foo`
foo!int(); //Error: ` safe` function `D main` cannot call
` system` function `onlineapp.foo!int.foo`
}
```
When template function foo is called and its inferred
attributes are not compatible with attributes of main, errors
are not really useful. Compiler print that foo!float is not
pure or foo!int is not safe but doesn't tell why. Is in dmd
some flag that print errors similarly to this?:
```d
void main() safe pure{
foo!long();
foo!float();
//Error: `pure` function `D main` cannot call impure
function `onlineapp.foo!float.foo`
//Error: potentially `pure` function
`onlineapp.foo!float.foo` cannot call impure function
`onlineapp.bar!float.bar`
//Error: potentially `pure` function
`onlineapp.bar!float.bar` cannot access mutable static data `i`
foo!int();
//Error: ` safe` function `D main` cannot call ` system`
function `onlineapp.foo!int.foo`
//Error: potentially ` safe` function
`onlineapp.foo!int.foo` cannot call ` system` function
`onlineapp.bar!int.bar`
//Error: potentially ` safe` function
`onlineapp.bar!int.bar` cannot call ` system` delegate
`onlineapp.bar!int.bar.__lambda1`
}
```
Use `-verrors=context` for dmd
```d
static int i;
void bar(T)(){
static if(is(T == int))
(() system => 1)();
static if(is(T == float))
i = 42;
}
void foo(T)(){
bar!T();
}
void main() safe pure{
foo!long();
foo!float(); /+ onlineapp.d(16): Error: `pure` function `D main`
cannot call impure function `onlineapp.foo!float.foo`
foo!float();
^ +/
foo!int(); /+onlineapp.d(18): Error: ` safe` function `D main`
cannot call ` system` function `onlineapp.foo!int.foo`
foo!int();
^ +/
}
```
May 27 2022
On Friday, 27 May 2022 at 08:39:08 UTC, vit wrote:
Is in dmd some flag that print errors similarly to this?:
```d
void main() safe pure{
foo!long();
foo!float();
//Error: `pure` function `D main` cannot call impure
function `onlineapp.foo!float.foo`
//Error: potentially `pure` function
`onlineapp.foo!float.foo` cannot call impure function
`onlineapp.bar!float.bar`
//Error: potentially `pure` function
`onlineapp.bar!float.bar` cannot access mutable static data `i`
```
No, there is nothing like this, at least not yet. It's being
worked on, though.
https://github.com/dlang/dmd/pull/13957
https://github.com/dlang/dmd/pull/12383
May 27 2022