Bug 18870 – Link failure only with -allinst for code in isExpression

Hi, I'm using version 2.080. Here's a reduced version of some code I had a problem with: import std.datetime.date; import std.stdio; void main() { writef("%s", TimeOfDay()); } It compiles and runs fine for me with no flags to dmd, but here's what happens with -allinst: $ dmd -allinst broken.d broken.o: In function `_D3std5range10primitives__T5doPutTSQBh6format__T11hasToStringTSQCj8datetime4date9TimeOfDayTaZ9__lambda2MFZ1STaZQDgFNaNbNiNfKQDmKaZv': broken.d:(.text._D3std5range10primitives__T5doPutTSQBh6format__T11hasToStringTSQCj8datetime4date9TimeOfDayTaZ9__lambda2MFZ1STaZQDgFNaNbNiNfKQDmKaZv[_D3std5range10primitives__T5doPutTSQBh6format__T11hasToStringTSQCj8datetime4date9TimeOfDayTaZ9__lambda2MFZ1STaZQDgFNaNbNiNfKQDmKaZv]+0x14): undefined reference to `_D3std6format__T11hasToStringTSQBd8datetime4date9TimeOfDayTaZ9__lambda2MFZ1S3putMFNaNbNiNfaZv' broken.o: In function `_D3std5range10primitives__T5doPutTSQBh6format__T11hasToStringTSQCj8datetime4date9TimeOfDayTaZ9__lambda2MFZ1STaZQDgFNaNbNiNfKQDmaZv': broken.d:(.text._D3std5range10primitives__T5doPutTSQBh6format__T11hasToStringTSQCj8datetime4date9TimeOfDayTaZ9__lambda2MFZ1STaZQDgFNaNbNiNfKQDmaZv[_D3std5range10primitives__T5doPutTSQBh6format__T11hasToStringTSQCj8datetime4date9TimeOfDayTaZ9__lambda2MFZ1STaZQDgFNaNbNiNfKQDmaZv]+0x14): undefined reference to `_D3std6format__T11hasToStringTSQBd8datetime4date9TimeOfDayTaZ9__lambda2MFZ1S3putMFNaNbNiNfaZv' broken.o: In function `_D3std5range10primitives__T5doPutTSQBh6format__T11hasToStringTSQCj8datetime4date9TimeOfDayTaZ9__lambda2MFZ1STxaZQDhFNaNbNiNfKQDnKxaZv': broken.d:(.text._D3std5range10primitives__T5doPutTSQBh6format__T11hasToStringTSQCj8datetime4date9TimeOfDayTaZ9__lambda2MFZ1STxaZQDhFNaNbNiNfKQDnKxaZv[_D3std5range10primitives__T5doPutTSQBh6format__T11hasToStringTSQCj8datetime4date9TimeOfDayTaZ9__lambda2MFZ1STxaZQDhFNaNbNiNfKQDnKxaZv]+0x14): undefined reference to `_D3std6format__T11hasToStringTSQBd8datetime4date9TimeOfDayTaZ9__lambda2MFZ1S3putMFNaNbNiNfaZv' collect2: error: ld returned 1 exit status Error: linker exited with status 1 The missing symbol demangles to this: pure nothrow @nogc @safe void std.format.hasToString!(const(std.datetime.date.TimeOfDay), char).__lambda2().S.put(char) (That __lambda2 is from an isExpression, so it makes sense for it to be missing from the object file.)

Reduced: ---- void put(R)(R r) { r.put(); } enum hasToString = is(typeof({ static struct S { void put() {} } enum e = is(typeof(put(S.init))); })); static assert(hasToString); void main() {} ----

Because the isExpression code isn't being used at runtime, I've been working around the problem with hacks like this. (Not pretty, but at least it stops the bug from being a blocker.) pragma(mangle, "_D3std6format__T11hasToStringTSQBd8datetime4date9TimeOfDayTaZ9__lambda2MFZ1S3putMFNaNbNiNfaZv") void bug18870kludge1(char c) { import logger = std.experimental.logger; logger.fatal("https://issues.dlang.org/show_bug.cgi?id=18870"); }

Both the original and reduced examples seem to link successfully when compiled with dmd 2.098 (with -allinst). Please add any relevant tests and close.