Bug 12839 – std.parallelism with nested functions and lambdas. Segfault

import std.parallelism; import std.algorithm; auto loo(int a, int[] b) { auto inner(int c) { return a; } return b.map!((x) => () => inner(x)); } void main() { defaultPoolThreads = 1; auto res = loo(3, [1,2,3]); auto jobs = taskPool.map!"a()"(res); } This segfaults. More details to come.

Interestingly, the following works fine. It should be the same as the lambda-based version, no? import std.parallelism; import std.algorithm; auto loo(int a, int[] b) { auto inner(int c) { return a; } auto wrapper(int x) { auto wrapperInner() { return inner(x); } return &wrapperInner; } return b.map!wrapper; } void main() { defaultPoolThreads = 1; auto res = loo(3, [1,2,3]); auto jobs = taskPool.map!"a()"(res); assert(jobs.front() == 3); }

sorry, ignore the () on jobs.front

Fails on win64 too.

Even replacing "taskPool.amap" with "map!"a()".array", it still segfaults. import std.algorithm; import std.array; auto loo(int a, int[] b) { auto inner(int c) { return a; // debugger caught SEGV at this line } return b.map!((x) => () => inner(x)); } void main() { auto res = loo(3, [1,2,3]); auto jobs = map!"a()"(res).array; // evaluate eagerly } I reduced 'map' version, and found that just returning "() => () => inner()" and calling it segfaults. IIUC this seems a compiler bug. auto loo(int a) { auto inner() { return a; // debugger caught SEGV at this line } return () => () => inner(); } void main() { assert(loo(3)()() == 3); }

Now it gives ice. auto loo(int a) { auto inner() { return a; // debugger caught SEGV at this line } return () => () => inner(); } void main() { assert(loo(3)()() == 3); } DMD v2.068-devel-df9b8af-dirty DEBUG dmd: toir.c:183: elem* getEthis(Loc, IRState*, Dsymbol*): Assertion `thisfd->isNested() || thisfd->vthis' failed. Aborted

See also issue #16051, which deals with the same ICE. Not sure if it's a duplicate, though.

All the examples in this bug report now compile successfully. However, Issue 16051 is still valid. Closing as fixed.