On Friday, 23 June 2023 at 14:22:24 UTC, DLearner wrote:
Hi
Was looking for compile-time detection of a struct variable.
However, the following test code gave the two 'FAILS' shown
below.
Comments?
```
void main() {
import std.stdio : writeln;
import std.traits;
string mxnTst(string VarName) {
return
`static if (is(typeof(` ~ VarName ~ `) == char)) {` ~
`writeln("` ~ VarName ~ ` ", " is a char");` ~
`} else static if (__traits(isPOD, typeof(` ~ VarName ~
`))) {` ~
`writeln("` ~ VarName ~ ` ", " is a struct");` ~
`} else static if (is(typeof(` ~ VarName ~ `) == int)) {`
~
`writeln("` ~ VarName ~ ` ", " is an int");` ~
`} else {` ~
`static assert(false, "mxnTst Variable '` ~ VarName ~
`' is of unknown type");` ~
`}`
;
}
char char1;
int int1;
byte byte1;
struct foo {
int fooint;
char foochar;
}
foo foovar1;
mixin(mxnTst("char1")); // Expected: char1 is a char.
Actual: char1 is a char. (ok)
mixin(mxnTst("int1")); // Expected: int1 is an int.
Actual: int1 is a struct. (FAIL)
mixin(mxnTst("foovar1")); // Expected: foovar1 is a struct.
Actual: foovar1 is a struct. (ok)
mixin(mxnTst("byte1")); // Expected: Run to fail with the
static assert message. Actual: byte1 is a struct. (FAIL)
}
```
```
static assert(__traits(isPOD, int)); // ok.
static assert(__traits(isPOD, byte)); // ok.
```
It's a bug in either the spec or the compiler.
