Add header dep graph script for cleanup verification

scripts/gen_header_dep_graph.sh

@@ -0,0 +1,100 @@
+#!/bin/bash
+# Generate header dependency graph + tsort cycle check.
+#
+# Outputs (under build/):
+#   header_deps_baseline.txt   - sorted, unique header->header (and .c->header)
+#                                edges derived from #include "..." directives.
+#   header_tsort_order.txt     - topological order produced by tsort.
+#   header_tsort_cycles.txt    - stderr from tsort; non-empty if there's a cycle.
+#   per_tu_deps.txt            - per-translation-unit transitive header lists
+#                                (one TU per line; basenames only; sorted).
+#
+# All headers / sources are reduced to basenames so renames in the cleanup are
+# easy to spot in the diff.
+
+set -euo pipefail
+
+repo_root="$(cd "$(dirname "$0")/.." && pwd)"
+cd "$repo_root"
+mkdir -p build
+
+edges_raw=build/header_edges_raw.txt
+edges_baseline=build/header_deps_baseline.txt
+tsort_order=build/header_tsort_order.txt
+tsort_cycles=build/header_tsort_cycles.txt
+per_tu=build/per_tu_deps.txt
+
+: > "$edges_raw"
+
+extract_edges() {
+    local src="$1"
+    local bn
+    bn=$(basename "$src")
+    # Match `#include "..."` (skip `<...>` system includes). Strip path, keep
+    # only the basename of the included file, so the graph collapses
+    # `../jemalloc.h` and similar relative paths into a single node.
+    awk '
+        /^[[:space:]]*#[[:space:]]*include[[:space:]]+"/ {
+            match($0, /"[^"]+"/)
+            inc = substr($0, RSTART + 1, RLENGTH - 2)
+            n = split(inc, parts, "/")
+            print parts[n]
+        }
+    ' "$src" | while read -r dep; do
+        printf '%s %s\n' "$bn" "$dep"
+    done
+}
+
+# Headers (include/jemalloc/internal/) — these are the nodes we care about for
+# cycle detection.
+for f in include/jemalloc/internal/*.h include/jemalloc/*.h; do
+    extract_edges "$f" >> "$edges_raw"
+done
+
+# Translation units (src/*.c) — included so that .c files appear as graph
+# sources in the baseline. They can't introduce cycles (nothing #includes a
+# .c), but the edges are useful when diffing later.
+for f in src/*.c; do
+    extract_edges "$f" >> "$edges_raw"
+done
+
+sort -u "$edges_raw" > "$edges_baseline"
+
+# tsort consumes "A B" pairs and reports cycles on stderr.
+: > "$tsort_cycles"
+if ! tsort "$edges_baseline" > "$tsort_order" 2> "$tsort_cycles"; then
+    echo "tsort exited non-zero; see $tsort_cycles" >&2
+fi
+
+# Per-translation-unit transitive header lists, harvested from the .d files
+# the build already produced (CC_MM=1 in the Makefile).
+: > "$per_tu"
+for d in src/*.d; do
+    [ -f "$d" ] || continue
+    tu=$(basename "${d%.d}.c")
+    # Strip the make rule prefix ("foo.o: foo.c \"), drop line continuations,
+    # collapse to basenames, sort+uniq.
+    deps=$(
+        tr '\n' ' ' < "$d" \
+            | sed -E 's/\\//g' \
+            | tr ' ' '\n' \
+            | grep -E '\.h$' \
+            | awk -F/ '{print $NF}' \
+            | sort -u \
+            | tr '\n' ' ' \
+            | sed -E 's/[[:space:]]+$//'
+    )
+    printf '%s: %s\n' "$tu" "$deps" >> "$per_tu"
+done
+sort -o "$per_tu" "$per_tu"
+
+edge_count=$(wc -l < "$edges_baseline" | tr -d ' ')
+cycle_bytes=$(wc -c < "$tsort_cycles" | tr -d ' ')
+tu_count=$(wc -l < "$per_tu" | tr -d ' ')
+echo "edges: $edge_count"
+echo "translation units: $tu_count"
+echo "tsort cycle output bytes: $cycle_bytes"
+if [ "$cycle_bytes" -gt 0 ]; then
+    echo "---- tsort cycle report ----"
+    cat "$tsort_cycles"
+fi