Bug 20811 – Regression as of 2.066.0 - CTFE static variable retained across calls

Here's a fun one: string bug() { char[1] counter = "0"; counter[$-1]++; return counter.dup; } pragma(msg, bug()); pragma(msg, bug()); pragma(msg, bug()); pragma(msg, bug()); Each call returns something different; the counter variable is apparently retained between calls. And if you call bug() at runtime after that, it retains the last counter. Add this in: void main() { assert(bug == "5"); assert(bug == "5"); assert(bug == "5"); assert(bug == "5"); } and it passes! Unless you change the msgs lolol. Same behavior on Windows and Linux. I almost didn't want to report this because having a compile-time counter like this can actually be pretty useful! But it is also obviously wrong. History output: Random error prior to 63. Worked correctly between 63 and 65, then 2.066.0: Status -6 with output: dmd: interpret.c:4025: void Interpreter::interpretAssignCommon(BinExp*, Expression* (*)(Type*, Expression*, Expression*), int): Assertion `newval->op == TOKarrayliteral' failed. 2.067.1 to 2.071.2: Failure with output: ----- 1 2 3 4

> having a compile-time counter like this can actually be pretty useful There was a plan to add a new primary exp for counting, see the defunct PR https://github.com/dlang/dmd/pull/10131/files. The problem with a CTFE counter is that it must allow static CTFE variables, this is not correct. global and mutable states are forbidden in CTFE, they can only change in a function body

@ibuclaw created dlang/dmd pull request #14729 "fix Issue 20811 - Regression as of 2.066.0 - CTFE static variable retained across calls" fixing this issue: - fix Issue 20811 - Regression as of 2.066.0 - CTFE static variable retained across calls https://github.com/dlang/dmd/pull/14729

dlang/dmd pull request #14729 "fix Issue 20811 - Regression as of 2.066.0 - CTFE static variable retained across calls" was merged into stable: - 6205ad3ebcc936545ae623ec1527dc1fe95cf804 by Iain Buclaw: fix Issue 20811 - Regression as of 2.066.0 - CTFE static variable retained across calls https://github.com/dlang/dmd/pull/14729

dlang/dmd pull request #14765 "merge stable" was merged into master: - 1f286b9cec6c83bf24028113407aee057f4d357a by Iain Buclaw: fix Issue 20811 - Regression as of 2.066.0 - CTFE static variable retained across calls https://github.com/dlang/dmd/pull/14765