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Fix another compile error related to generic visitors.

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This commit is contained in:
Sönke Ludwig 2020-04-04 15:15:53 +02:00
parent ab3e8c5cf8
commit a3078c34fc
1 changed files with 16 additions and 1 deletions
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17
source/taggedalgebraic/visit.d
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@ -128,6 +128,21 @@ unittest {
//static assert(!is(typeof(u.visit!((int) {}, (float) {}, () {}, (_) {})))); // superfluous generic handler
}
unittest {
// make sure that the generic handler is not instantiated with types for
// which it doesn't compile
class C {}
union U { int i; C c; }
TaggedUnion!U u;
u.visit!(
(C c) => c !is null,
(v) {
static assert(is(typeof(v) == int));
return v != 0;
}
);
}
/** The same as `visit`, except that failure to handle types is checked at runtime.
@ -258,7 +273,7 @@ private template selectHandler(T, VISITORS...)
static if (i < VISITORS.length) {
alias fun = VISITORS[i];
static if (!isSomeFunction!fun) {
static if (isSomeFunction!(fun!T)) {
static if (__traits(compiles, fun!T) && isSomeFunction!(fun!T)) {
static if (ParameterTypeTuple!(fun!T).length == 1) {
static if (matched_index >= 0) enum genericIndex = "Only one generic visitor allowed";
else enum genericIndex = genericIndex!(i+1, i);