Bug 16047 – Range violation in setting multi-dimensional AA entries

The following code results in a range violation for the second assignment to `aa`, while the first assignment to `aa` works as expected: unittest { import std.datetime; struct S { string s; this(string s) { this.s = s; } } SysTime[string][string] aa; aa["bar"]["bar"] = SysTime.init; aa[S("baz").s]["baz"] = SysTime.init; // Range violation } Any further reduction of the example eliminates the issue.

Workaround: use `require` aa.require(S("baz").s, null)["baz"] = SysTime.init;

Tighter repro: struct Reassignable { void opAssign(Reassignable) {} } int s() { return 1; } void main() { Reassignable[int][int] aa; aa[0][0] = Reassignable.init; aa[s()][0] = Reassignable.init; // range violation }

What happens here is that the complex expression for the first index forces DMD to allocate a temporary. In the course of doing so, it forgets to indicate that the temporary is for a nested assignment, and the temporary (which is a plain IndexExp, not an assignment) runs into a range error.

@FeepingCreature updated dlang/dmd pull request #10422 "fix issue 16048: range error when assigning nested aa with temporary" fixing this issue: - fix issue 16047: when extracting temporaries from an index expression for assignment, mark the expression as assigning. This avoids the temporaries encountering a range error with nested associative arrays. https://github.com/dlang/dmd/pull/10422

dlang/dmd pull request #10422 "fix issue 16047: range error when assigning nested aa with temporary" was merged into master: - c3d94591422f5d9366639683c5a0c50f4c48aa64 by Mathis Beer: fix issue 16047: when extracting temporaries from an index expression for assignment, mark the expression as assigning. This avoids the temporaries encountering a range error with nested associative arrays. https://github.com/dlang/dmd/pull/10422