GNU and Clang C++ modes: members skipped by a designated initializer #260

^{Originally posted by wchilders-nvidia October 9, 2026}

Issue Summary

In GNU C++ modes before C++20 and in all Clang C++ modes, a member that was
not designated, but that precedes a designated member, can be zero-initialized
instead of being initialized from its default member initializer.

Reproducing Source Code

struct P { int x = 1, y = 2, z = 3; };
P p = { .x = 10, .z = 30 };  // p.y was is 0.  It should be 2.

Command-line Options

cpfe --gnu_version=170100

Type of Issue

[Front End] This code SHOULD compile with these options.

Additional Details

No response

Reproducing (Standard) Configuration(s)

linux-gcc-debug

Reproducing (Non-standard) Configuration

No response

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