Bug 17703 – __traits(compiles, a[] = b[]) generates errors without surrounding parentheses

void Test(T...)() { static assert(__traits(compiles, T[0] = T[1]), "Doesn't compile"); } void main() { int x; int y; Test!(x, y)(); } This code fails to compile with: (3): Error: found '=' when expecting ')' following template argument list (3): Error: found 'T' when expecting ')' (3): Error: found '[' when expecting ';' (3): Error: found ']' when expecting ';' following statement (3): Error: found ')' instead of statement It used to compile a few years ago. Enclosing `T[0] = T[1]` in parentheses will allow it to compile. void Test(T...)() { static assert(__traits(compiles, (T[0] = T[1])), "Doesn't compile"); } void main() { int x; int y; Test!(x, y)(); }

Looks like the assignment expression parsing isn't fully working, below example works. void works(int a, int b) { static assert(__traits(compiles, a = b)); } Also the specs support the case http://dlang.org/spec/grammar.html#TraitsArgument I went back until 2.050 and it still wouldn't accept the code, downgrading to a normal bug. Simple workaround: __traits(compiles, { exp; })

Just ran into this too.

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