Add clang debug sanitizer flag and fix related warnings

CHANGELOG.md

@@ -21,7 +21,7 @@
 - Fix regression where empty namespace in schema does not reset root scope
   correctly in parser (#265).
 - Fix lexer checks that breaks with UTF-8, notably UTF-8 schema comments (#267).
-- Fix UB in memcpy(p, 0, 0) by initializing scope prefix (mostly to silence sanitizers).
+- Add sanitizer flag for clang debug and related warnings (input from several PRs incl. #237)
 
 ## [0.6.1]
 

CMakeLists.txt

@@ -188,6 +188,10 @@ if (CMAKE_C_COMPILER_ID MATCHES "Clang" AND NOT "${CMAKE_CXX_SIMULATE_ID}" STREQ
     if (FLATCC_IGNORE_CONST_COND)
         set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-tautological-constant-out-of-range-compare")
     endif()
+    if (CMAKE_BUILD_TYPE MATCHES Debug)
+        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fsanitize=undefined")
+        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=undefined")
+    endif()
     # Suppress warning relaxed in clang-6, see https://reviews.llvm.org/D28148
     if (CMAKE_C_COMPILER_VERSION VERSION_LESS 6)
         set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-missing-field-initializers")

src/compiler/parser.c

@@ -1270,7 +1270,6 @@ static void push_token(fb_parser_t *P, long id, const char *first, const char *l
     size_t offset;
     fb_token_t *t;
 
-    P->te = P->ts + P->tcapacity;
     if (P->token == P->te) {
         offset = (size_t)(P->token - P->ts);
         P->tcapacity = P->tcapacity ? 2 * P->tcapacity : 1024;

src/runtime/builder.c

@@ -177,7 +177,7 @@ int flatcc_builder_default_alloc(void *alloc_context, iovec_t *b, size_t request
     return 0;
 }
 
-#define T_ptr(base, pos) ((void *)((uint8_t *)(base) + (uoffset_t)(pos)))
+#define T_ptr(base, pos) ((void *)((size_t)(base) + (size_t)(pos)))
 #define ds_ptr(pos) (T_ptr(B->buffers[flatcc_builder_alloc_ds].iov_base, (pos)))
 #define vs_ptr(pos) (T_ptr(B->buffers[flatcc_builder_alloc_vs].iov_base, (pos)))
 #define pl_ptr(pos) (T_ptr(B->buffers[flatcc_builder_alloc_pl].iov_base, (pos)))