From 50ae1b0cadd8a23c7d8290cd72e172c9861aec1c Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Sun, 10 Dec 2023 14:14:57 -0700
Subject: [PATCH] Use GNU89 for kernel C

C99/GNU99 is obviously well established and a sensible choice of
standard for a C code base. Still, in some environments where it
remains useful to compile Chez Scheme, the default `gcc` mode is
GNU89.

Since C isn't the main development language for Chez Scheme, since
it's easy to stick to GNU89, and since that usefully reduces build
friction, this commit makes the few changes needs to get back to
GNU89. GitHub CI is configured to use `-std=gnu89` for two builds to
help maintain the choice.

GNU89 is a little more flexible than C89 (ANSI C), because it allows
declarations in the middle of a block, but it does not allow variables
defined in the parentheses after `for`. We also rely on GNU extensions
for inlining declarations.
---
 .github/workflows/ci.yml |  2 ++
 c/foreign.c              |  3 ++-
 c/self-exe.c             | 12 ++++++++----
 3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 5f1eb914c..1140a9f4b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -23,6 +23,7 @@ jobs:
             os: ubuntu-22.04
           - machine: ta6le
             os: ubuntu-22.04
+            configure: CFLAGS+=-std=gnu89
           - machine: ta6le
             os: ubuntu-22.04
             variant: reboot
@@ -44,6 +45,7 @@ jobs:
           - machine: ta6nt
             os: windows-2022
             toolchain: gcc
+            configure: CFLAGS+=-std=gnu89
     runs-on: ${{ matrix.config.os }}
     env:
       TARGET_MACHINE: ${{ matrix.config.machine }}
diff --git a/c/foreign.c b/c/foreign.c
index c8493e122..42c7a6e63 100644
--- a/c/foreign.c
+++ b/c/foreign.c
@@ -134,7 +134,8 @@ static ptr lookup_dynamic(const char *s, ptr tbl) {
         if (!handle) {
             HMODULE *modules = S_enum_process_modules();
             if (modules) {
-                for (HMODULE *m = modules; *m; ++m) {
+                HMODULE *m;
+                for (m = modules; *m; ++m) {
                     value = dlsym(*m, s);
                     if (value != NULL) break;
                 }
diff --git a/c/self-exe.c b/c/self-exe.c
index 3259d0e7d..fecc82fb1 100644
--- a/c/self-exe.c
+++ b/c/self-exe.c
@@ -73,7 +73,8 @@ static char *wide_to_utf8(const wchar_t *arg) {
 
 static char *get_process_executable_path(const char *exec_file) {
   wchar_t *path = NULL;
-  for (DWORD n = 0, sz = 256;; sz *= 2) {
+  DWORD n, sz;
+  for (n = 0, sz = 256;; sz *= 2) {
     path = (wchar_t *)malloc(sz * sizeof(wchar_t));
     if (path == NULL) {
       return NULL;
@@ -153,7 +154,8 @@ static char *get_self_path_platform() {
      sysctl may not return the desired path if there are multiple hardlinks
      to the file. */
 #if __FreeBSD_version >= 1300057
-  for (size_t bufsize = 256;; bufsize *= 2) {
+  size_t bufsize;
+  for (bufsize = 256;; bufsize *= 2) {
     char *buf = (char *)malloc(bufsize);
     if (buf == NULL) {
       return NULL;
@@ -174,7 +176,8 @@ static char *get_self_path_platform() {
   while (*p++ != 0)
     ;
   /* Iterate through auxiliary vectors for AT_EXECPATH. */
-  for (Elf_Auxinfo *aux = (Elf_Auxinfo *)p; aux->a_type != AT_NULL; aux++) {
+  Elf_Auxinfo *aux;
+  for (aux = (Elf_Auxinfo *)p; aux->a_type != AT_NULL; aux++) {
     if (aux->a_type == AT_EXECPATH) {
       return copy_string((char *)aux->a_un.a_ptr);
     }
@@ -238,7 +241,8 @@ static char *get_self_path_generic(const char *exec_file) {
   if (s == NULL) {
     return NULL;
   }
-  for (char *p = s + strspn(s, ":"); *p != '\0'; p += strspn(p, ":")) {
+  char *p;
+  for (p = s + strspn(s, ":"); *p != '\0'; p += strspn(p, ":")) {
     char *t = p;
     p += strcspn(p, ":");
     if (*p != '\0') {