fix(interop): initialise the x265 CSV column indices so gcc -O2 sees no maybe-uninitialized

.github/workflows/ci.yml

@@ -45,6 +45,10 @@ jobs:
           glslangValidator --version
       - name: Configure + build
         run: meson setup build && ninja -C build
+      - name: Optimised gcc build (-O2, warnings are errors)
+        # gcc raises -Wmaybe-uninitialized only with the optimiser on, which the
+        # default debug build above does not run.
+        run: CC=gcc meson setup build-o2 --buildtype=debugoptimized && ninja -C build-o2
       - name: Test (fast suite — interop ABI + shader compile)
         run: meson test -C build --suite=fast --print-errorlogs
       - name: clang-format (touched-tree clean)

CHANGELOG.md

@@ -103,6 +103,14 @@ All notable changes to Pelorus are documented here. The format is
   `base` and `n1.2.3` branches and wrote `core.hooksPath`, `commit.gpgsign` and
   `user.name` into the repository's config. The checker now drops the
   repository-selecting variables first, and a regression proves it.
+- **The x265 CSV reader initialises its column indices before the header row
+  sets them.** `x265_csv_read_rows()` left the column-index struct
+  uninitialised until the header was read, and gcc 16 at `-O2` reported seven
+  `-Wmaybe-uninitialized` warnings (`type`, `poc`, `qp`, `bits`, `psnr_y/u/v`).
+  Every index now starts at -1 ("absent"), which the readers already treat as a
+  missing column, so behaviour is unchanged. CI gains an optimised gcc build
+  with warnings as errors; the default debug build never ran the optimiser and
+  could not see this class of warning.
 
 ### Security
 

changelog.d/fixed/qp-report-csv-cols-initialised.md

@@ -0,0 +1,8 @@
+- **The x265 CSV reader initialises its column indices before the header row
+  sets them.** `x265_csv_read_rows()` left the column-index struct
+  uninitialised until the header was read, and gcc 16 at `-O2` reported seven
+  `-Wmaybe-uninitialized` warnings (`type`, `poc`, `qp`, `bits`, `psnr_y/u/v`).
+  Every index now starts at -1 ("absent"), which the readers already treat as a
+  missing column, so behaviour is unchanged. CI gains an optimised gcc build
+  with warnings as errors; the default debug build never ran the optimiser and
+  could not see this class of warning.

libpelorus/src/qp_report_csv.c

@@ -414,7 +414,9 @@ static pel_result x265_csv_read_rows(FILE *fp, PelorusX265Frame *out_frames, siz
 {
     char line[PEL_CSV_LINE_MAX]; /* bounded, fixed (Po10): no heap, no VLA  */
     char *fields[PEL_CSV_MAX_FIELDS];
-    csv_cols cols;
+    /* Every index starts "absent" (-1): a row is then never admitted before a header has set the
+     * real indices, and the compiler sees a defined value on every path. */
+    csv_cols cols = {-1, -1, -1, -1, -1, -1, -1};
 
     while (fgets(line, (int)sizeof(line), fp) != NULL) {
         size_t nf = split_fields(line, fields, PEL_CSV_MAX_FIELDS);