GCC Newspaper
JUNE 15, 2026
gcc Proposed

Stage2 build failure due to uninitialized variable

GCC trunk fails to bootstrap due to a maybe-uninitialized variable warning being treated as an error in stage2.

Ulrich Drepper reports that the GCC trunk fails to bootstrap in stage2 due to a -Werror=maybe-uninitialized error. The error occurs in tree-vect-stmts.cc where the variable stride_step may be used uninitialized. He asks if he should file a bug report.

In the Thread 1 participant
  1. Sam James <sam@gentoo.org> other

    Implied agreement/acknowledgment that the issue exists.

In Details

This indicates a regression in the GCC trunk. The -Werror flag promotes warnings to errors, which is commonly used in build systems to ensure code quality. The specific error involves tree-vect-stmts.cc, which is part of the tree-vectorization pass in GCC's middle-end.

For Context

When building a compiler like GCC, it's common to use a multi-stage process (bootstrap) where the compiler compiles itself. This report indicates a failure during the second stage of this process. The failure is caused by a warning (about a potentially uninitialized variable) being treated as a fatal error. This usually indicates a recent change in the code introduced the problem.

Filed Under: gccbootstrapbuild failureWerroruninitialized variable