actually link to <sqlite3.h> when -tags libsqlite3

sqlite3-binding.c

@@ -17,6 +17,7 @@
 ** language. The code for the "sqlite3" command-line shell is also in a
 ** separate file. This file contains only code for the core SQLite library.
 */
+#ifndef USE_LIBSQLITE3
 #define SQLITE_CORE 1
 #define SQLITE_AMALGAMATION 1
 #ifndef SQLITE_PRIVATE
@@ -197846,5 +197847,9 @@ static int sqlite3Fts5VocabInit(Fts5Global *pGlobal, sqlite3 *db){
 
 
 #endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS5) */
+#else // USE_LIBSQLITE3
+// If users really want to link against the system sqlite3 we
+// need to make this file a noop.
+#endif
 
 /************** End of fts5.c ************************************************/

sqlite3-binding.h

@@ -30,6 +30,7 @@
 ** the version number) and changes its name to "sqlite3.h" as
 ** part of the build process.
 */
+#ifndef USE_LIBSQLITE3
 #ifndef SQLITE3_H
 #define SQLITE3_H
 #include <stdarg.h>     /* Needed for the definition of va_list */
@@ -10338,5 +10339,9 @@ struct fts5_api {
 #endif
 
 #endif /* _FTS5_H */
+#else // USE_LIBSQLITE3
+// If users really want to link against the system sqlite3 we
+// need to make this file a noop.
+#endif
 
 /******** End of fts5.h *********/

sqlite3ext.h

@@ -1,3 +1,4 @@
+#ifndef USE_LIBSQLITE3
 /*
 ** 2006 June 7
 **
@@ -12,7 +13,7 @@
 ** This header file defines the SQLite interface for use by
 ** shared libraries that want to be imported as extensions into
 ** an SQLite instance.  Shared libraries that intend to be loaded
-** as extensions by SQLite should #include this file instead of 
+** as extensions by SQLite should #include this file instead of
 ** sqlite3.h.
 */
 #ifndef SQLITE3EXT_H
@@ -543,18 +544,22 @@ typedef int (*sqlite3_loadext_entry)(
 #endif /* !defined(SQLITE_CORE) && !defined(SQLITE_OMIT_LOAD_EXTENSION) */
 
 #if !defined(SQLITE_CORE) && !defined(SQLITE_OMIT_LOAD_EXTENSION)
-  /* This case when the file really is being compiled as a loadable 
+  /* This case when the file really is being compiled as a loadable
   ** extension */
 # define SQLITE_EXTENSION_INIT1     const sqlite3_api_routines *sqlite3_api=0;
 # define SQLITE_EXTENSION_INIT2(v)  sqlite3_api=v;
 # define SQLITE_EXTENSION_INIT3     \
     extern const sqlite3_api_routines *sqlite3_api;
 #else
-  /* This case when the file is being statically linked into the 
+  /* This case when the file is being statically linked into the
   ** application */
 # define SQLITE_EXTENSION_INIT1     /*no-op*/
 # define SQLITE_EXTENSION_INIT2(v)  (void)v; /* unused parameter */
 # define SQLITE_EXTENSION_INIT3     /*no-op*/
 #endif
 
 #endif /* SQLITE3EXT_H */
+#else // USE_LIBSQLITE3
+ // If users really want to link against the system sqlite3 we
+// need to make this file a noop.
+ #endif

tool/upgrade.go

@@ -37,18 +37,21 @@ func main() {
 	if err != nil {
 		log.Fatal(err)
 	}
-	defer resp.Body.Close()
 
 	b, err := ioutil.ReadAll(resp.Body)
 	if err != nil {
+		resp.Body.Close()
 		log.Fatal(err)
 	}
 
 	fmt.Printf("extracting %v\n", path.Base(url))
 	r, err := zip.NewReader(bytes.NewReader(b), resp.ContentLength)
 	if err != nil {
+		resp.Body.Close()
 		log.Fatal(err)
 	}
+	resp.Body.Close()
+
 	for _, zf := range r.File {
 		var f *os.File
 		switch path.Base(zf.Name) {
@@ -68,11 +71,27 @@ func main() {
 		if err != nil {
 			log.Fatal(err)
 		}
+
+		_, err = io.WriteString(f, "#ifndef USE_LIBSQLITE3\n")
+		if err != nil {
+			zr.Close()
+			f.Close()
+			log.Fatal(err)
+		}
 		_, err = io.Copy(f, zr)
-		f.Close()
 		if err != nil {
+			zr.Close()
+			f.Close()
 			log.Fatal(err)
 		}
+		_, err = io.WriteString(f, "#else // USE_LIBSQLITE3\n // If users really want to link against the system sqlite3 we\n// need to make this file a noop.\n #endif")
+		if err != nil {
+			zr.Close()
+			f.Close()
+			log.Fatal(err)
+		}
+		zr.Close()
+		f.Close()
 		fmt.Printf("extracted %v\n", filepath.Base(f.Name()))
 	}
 }