C import drops object macros whose body is a bare identifier

• Type: bug (C header import, macro export) — Track A.
• Filed: 2026-10-05 from ~/museum_landkaart, the ESP-IDF ABI check.

Repro

cat > mh.h <<'H'
#define LIT 7
#define ALIAS_MACRO LIT
#define EXPR_MACRO (LIT + 1)
#define my_true 1
#define ALIAS_TRUE my_true
enum e { E_ONE = 1, E_TWO };
#define ALIAS_ENUM E_TWO
H
for n in LIT ALIAS_MACRO EXPR_MACRO ALIAS_TRUE ALIAS_ENUM; do
  printf 'program p;\nuses mh;\nvar v: Int64;\nbegin\n  v := %s;\n  writeln(v);\nend.\n' $n > p.pas
  pascal26 -I. p.pas p && ./p
done
# LIT: 7   EXPR_MACRO: 8
# ALIAS_MACRO / ALIAS_TRUE / ALIAS_ENUM: error: undefined variable

Real-world

ESP-IDF esp_wifi.h's WIFI_INIT_CONFIG_DEFAULT() ingredients follow the pattern #if CONFIG_X #define WIFI_X CONFIG_X_NUM #else #define WIFI_X 0 #endif. On the taken branch they're aliases, so these are missing: WIFI_DYNAMIC_TX_BUFFER_NUM, WIFI_RX_MGMT_BUF_NUM_DEF, WIFI_DEFAULT_RX_BA_WIN, WIFI_SOFTAP_BEACON_MAX_LEN, WIFI_MGMT_SBUF_NUM, WIFI_STA_DISCONNECTED_PM_ENABLED (true), WIFI_DUMP_HESIGB_ENABLED (false), SNTP_OPMODE_POLL (enum). The same names on the 0 branch import fine (WIFI_STATIC_TX_BUFFER_NUM). Item D (WIFI_INIT_CONFIG_DEFAULT as a Pascal function) will need these.

Expected

Export an alias the same way as its target: resolve the chain to a constant expression, or to the enum constant.

Acceptance

All five names in the repro print 7, 8, 1, 2. Then ./build.sh qemu-prog test/abi_import_check.pas in ~/museum_landkaart/async prints ABI checked=70 mismatches=0 without -dALIAS_WORKAROUND. Today it fails to compile on exactly those 8; with the workaround the result is 70/70.