Bug 5531 – Erratic type deduction with pointers and type modifiers

Type deduction should match types which are a specialization of the given base type, but this doesn't work when type modifiers are involved. Here is a list of test cases which have been rigged to pass with the current compiler, but each test with a FIXME on should be considered wrong. template ap(T : int*) { enum ap = 1; } static assert(ap!(int*)); static assert(ap!(const(int*))); // FIXME: should not match static assert(ap!(const(int)*)); // FIXME: should not match static assert(ap!(immutable(int*))); // FIXME: should not match static assert(ap!(immutable(int)*)); // FIXME: should not match static assert(ap!(shared(int*))); // FIXME: should not match static assert(ap!(shared(int)*)); // FIXME: should not match template bp(T : const(int*)) { enum bp = 1; } static assert(bp!(int*)); static assert(bp!(const(int*))); static assert(bp!(const(int)*)); static assert(bp!(immutable(int*))); static assert(bp!(immutable(int)*)); static assert(bp!(shared(int*))); // FIXME: should not match static assert(bp!(shared(int)*)); // FIXME: should not match template cp(T : const(int)*) { enum cp = 1; } static assert(cp!(int*)); static assert(cp!(const(int*))); // FIXME: should not match (const ptr) static assert(cp!(const(int)*)); static assert(cp!(immutable(int*))); // FIXME: should not match (immutable ptr) static assert(cp!(immutable(int)*)); static assert(cp!(shared(int*))); // FIXME: should not match static assert(cp!(shared(int)*)); // FIXME: should not match template dp(T : U*, U) { alias U dp; } static assert(is(dp!(int*) == int)); static assert(is(dp!(const(int*)) == const(int))); // FIXME: should not match (const ptr) static assert(is(dp!(const(int)*) == const(int))); static assert(is(dp!(immutable(int*)) == immutable(int))); // FIXME: should not match (immutable ptr) static assert(is(dp!(immutable(int)*) == immutable(int))); static assert(is(dp!(shared(int*)) == shared(int))); // FIXME: should not match (shared ptr) static assert(is(dp!(shared(int)*) == shared(int))); template ep(T : const(U*), U) { alias U ep; } static assert(is(ep!(int*) == int)); static assert(is(ep!(const(int*)) == int)); static assert(is(ep!(const(int)*) == int)); static assert(is(ep!(immutable(int*)) == int)); static assert(is(ep!(immutable(int)*) == int)); static assert(!is(ep!(shared(int*)))); // no match static assert(!is(ep!(shared(int)*))); // no match template fp(T : const(U)*, U) { alias U fp; } static assert(is(fp!(int*) == int)); static assert(is(fp!(const(int*)) == int)); // FIXME: should not match (const ptr) static assert(is(fp!(const(int)*) == int)); static assert(is(fp!(immutable(int*)) == int)); // FIXME: should not match (immutable ref) static assert(is(fp!(immutable(int)*) == int)); static assert(!is(fp!(shared(int*)))); // no match static assert(!is(fp!(shared(int)*))); // no match

These seem to have been mostly fixed (or, at least, changed) since they were posted. (In reply to Michel Fortin from comment #0) > template ap(T : int*) { > enum ap = 1; > } > > static assert(ap!(int*)); > static assert(ap!(const(int*))); // FIXME: should not match > static assert(ap!(const(int)*)); // FIXME: should not match > static assert(ap!(immutable(int*))); // FIXME: should not match > static assert(ap!(immutable(int)*)); // FIXME: should not match > static assert(ap!(shared(int*))); // FIXME: should not match > static assert(ap!(shared(int)*)); // FIXME: should not match All fixed. > template bp(T : const(int*)) { > enum bp = 1; > } > > static assert(bp!(int*)); > static assert(bp!(const(int*))); > static assert(bp!(const(int)*)); > static assert(bp!(immutable(int*))); > static assert(bp!(immutable(int)*)); > static assert(bp!(shared(int*))); // FIXME: should not match > static assert(bp!(shared(int)*)); // FIXME: should not match Also fixed. > template cp(T : const(int)*) { > enum cp = 1; > } > > static assert(cp!(int*)); > static assert(cp!(const(int*))); // FIXME: should not match (const ptr) > static assert(cp!(const(int)*)); > static assert(cp!(immutable(int*))); // FIXME: should not match (immutable > ptr) > static assert(cp!(immutable(int)*)); Here it looks like it's intentionally allowing it to strip head const, which is generally harmless. > template dp(T : U*, U) { > alias U dp; > } > > static assert(is(dp!(int*) == int)); > static assert(is(dp!(const(int*)) == const(int))); // FIXME: should not > match (const ptr) > static assert(is(dp!(const(int)*) == const(int))); > static assert(is(dp!(immutable(int*)) == immutable(int))); // FIXME: should > not match (immutable ptr) > static assert(is(dp!(immutable(int)*) == immutable(int))); > > template fp(T : const(U)*, U) { > alias U fp; > } > > static assert(is(fp!(int*) == int)); > static assert(is(fp!(const(int*)) == int)); // FIXME: should not match > (const ptr) > static assert(is(fp!(const(int)*) == int)); > static assert(is(fp!(immutable(int*)) == int)); // FIXME: should not match > (immutable ref) > static assert(is(fp!(immutable(int)*) == int)); Ditto. > static assert(cp!(shared(int*))); // FIXME: should not match > static assert(cp!(shared(int)*)); // FIXME: should not match > > static assert(is(dp!(shared(int*)) == shared(int))); // FIXME: should not > match (shared ptr) > static assert(is(dp!(shared(int)*) == shared(int))); > > template ep(T : const(U*), U) { > alias U ep; > } > > static assert(!is(ep!(shared(int*)))); // no match > static assert(!is(ep!(shared(int)*))); // no match > > static assert(!is(fp!(shared(int*)))); // no match > static assert(!is(fp!(shared(int)*))); // no match Not sure about shared. I believe finalizing shared is still a work in progress. In any case, if any of these are still pertinent, they need to be filed as separate bugs. Aggregate bugs are not very actionable. I'll close this as it looks like the situation changed quite a bit in the 6 years since this was posted. Please file any remaining problems you believe are still pertinent today as new issues.