When a nested function calls an outer function with a large number of parameters, the first argument becomes corrupted. Test case: void outer( double x, double a, double b, double c, double d, double e, double f, double g, double h) { import std.stdio; writefln("x=%s a=%s b=%s c=%s d=%s e=%s f=%s g=%s h=%s", x, a, b, c, d, e, f, g, h); } void main() { void inner(double x) { outer(x, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0); } inner(999.0); } Here, the value of x in outer() is garbage. That is, the program SHOULD print: x=999 a=1 b=2 c=3 d=4 e=5 f=6 g=7 h=8 But instead, it prints something like: x=6.95253e-310 a=1 b=2 c=3 d=4 e=5 f=6 g=7 h=8 Reducing the number of parameters of outer() makes the problem go away. Also, interestingly, if the program is compiled with -O or -inline, the correct behaviour is restored.
The stack corruption I think is on the expected location of x when calling the function. Note that outer function is not needed, this also produces (same) corrupt output: import std.stdio; void main() { void inner(double x) { if(x == 999) // to show that x itself isn't corrupt { writefln("x=%s a=%s b=%s c=%s d=%s e=%s f=%s g=%s h=%s", x, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0); //outer(x, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0); } } inner(999.0); } Not sure how to edit the description, but definitely the number of parameters plays a role, and probably the inner function.
https://github.com/dlang/dmd/pull/6171
Commits pushed to master at https://github.com/dlang/dmd https://github.com/dlang/dmd/commit/815bb8f7b37882d6590281b3542548632c47be22 Fix issue 16555 - Generate correct code for pushing scalar parameters. https://github.com/dlang/dmd/commit/d91b678235d5357957762005bce7c4b46f265f62 Merge pull request #7890 from JinShil/fix_16555 Fix issue 16555 - Generate correct code for pushing scalar parameters. merged-on-behalf-of: Jacob Carlborg <jacob-carlborg@users.noreply.github.com>