[Bug c++/79937] [5/6/7 Regression] ICE in replace_placeholders_r

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79937

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |mpolacek at gcc dot gnu.org

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
The problem here is that we're messing with placeholders in an unrelated
object:
For
C c = bar(X{1});
store_init_value sees:
c = TARGET_EXPR <D.2332, bar (TARGET_EXPR <D.2298, {.i=1,
.n=(&<PLACEHOLDER_EXPR struct X>)->i}>)>
We call replace_placeholders for the RHS.  It's a TARGET_EXPR so we look at its
TARGET_EXPR_INITIAL, which is
bar (TARGET_EXPR <D.2298, {.i=1, .n=(&<PLACEHOLDER_EXPR struct X>)->i}>)
Then we walk this tree, find the
{.i=1, .n=(&<PLACEHOLDER_EXPR struct X>)->i}
CONSTRUCTOR, and recursively replace_placeholders_r for each value.  Eventually
we find the <PLACEHOLDER_EXPR struct X> but that's for another object, so we
crash.

I.e., we shouldn't look into the second TARGET_EXPR, it has nothing to do with
"C c".