c: add a workaround for SQLITE_TRANSIENT being mistranslated

See https://github.com/ziglang/zig/issues/15893

zig's translate-c creates an invalid type for SQLITE_TRANSIENT on some
architectures (aarch64, riscv64 and others).

We can work around this by making a C function that returns -1 cast to
the proper destructor type and use that from zig (thanks
https://github.com/Cloudef for mentioning this in this comment: https://github.com/ziglang/zig/issues/15893#issuecomment-1925092582)

4 files changed, 10 insertions, 0 deletions

diff --git a/c.zig b/c.zig
index 4589aef..3a43106 100644
--- a/c.zig
+++ b/c.zig
@@ -5,6 +5,7 @@ pub const c = if (@hasDecl(root, "loadable_extension"))
 else
     @cImport({
         @cInclude("sqlite3.h");
+        @cInclude("workaround.h");
     });
 
 // versionGreaterThanOrEqualTo returns true if the SQLite version is >= to the major.minor.patch provided.
diff --git a/c/loadable_extension.zig b/c/loadable_extension.zig
index 4b27534..fdfe15e 100644
--- a/c/loadable_extension.zig
+++ b/c/loadable_extension.zig
@@ -1,5 +1,6 @@
 const c = @cImport({
     @cInclude("loadable-ext-sqlite3ext.h");
+    @cInclude("workaround.h");
 });
 
 pub usingnamespace c;
diff --git a/c/workaround.c b/c/workaround.c
new file mode 100644
index 0000000..592d33d
--- /dev/null
+++ b/c/workaround.c
@@ -0,0 +1,5 @@
+#include "workaround.h"
+
+my_sqlite3_destructor_type sqliteTransientAsDestructor() {
+  return (my_sqlite3_destructor_type)-1;
+}
diff --git a/c/workaround.h b/c/workaround.h
new file mode 100644
index 0000000..ae243b8
--- /dev/null
+++ b/c/workaround.h
@@ -0,0 +1,3 @@
+typedef void (*my_sqlite3_destructor_type)(void *);
+
+my_sqlite3_destructor_type sqliteTransientAsDestructor();