Created attachment 67 [details]
sample

gdc -O1 and gdc -O2 produces faulty code for Adam Ruppe's jsvar.d.

how to reproduce:

get jsvar.d from here: https://github.com/adamdruppe/arsd/blob/master/jsvar.d

comment out line 47 (version=new_std_json;)

compile attached sample with -O0 and run it. it works ok.

compile attached sample with -O1 (or -O2) and run it. it segfaults.