Add a debug context for generics (#2455)

Author: fredrik-johansson

doc/source/gr_domains.rst

@@ -55,6 +55,31 @@ Domain properties
 
     Sets or retrieves the floating-point precision in bits.
 
+Debugging
+-------------------------------------------------------------------------------
+
+.. function:: void gr_ctx_init_debug(gr_ctx_t ctx, gr_ctx_t elem_ctx, int flags, double unable_probability)
+
+    Initialize *ctx* to a wrapper around *elem_ctx* for debugging.
+    This will execute supported methods (currently only a handful
+    of methods are supported, e.g. ``gr_add``) as if one is computing
+    directly over *elem_ctx*, but with added debugging features.
+
+    If *unable_probability* is positive, some methods will randomly return
+    ``GR_UNABLE`` and predicates will randomly return ``T_UNKNOWN``.
+
+    The following flags are supported:
+
+    * ``GR_DEBUG_WRAP`` - wrap elements in a box with a pointer. This allows
+      performing extra checks such as whether a variable is being cleared
+      twice or whether the wrong context object is passed as input. It can
+      also help catch some bugs that are not revealed when entries are
+      stored shallowly.
+
+    * ``GR_DEBUG_VERBOSE`` - print debugging information for each operation.
+
+    * ``GR_DEBUG_TIMING`` - print elapsed time for each operation.
+
 
 Groups
 -------------------------------------------------------------------------------

src/gr.h

@@ -725,6 +725,7 @@ typedef enum
     GR_CTX_GR_VEC,
     GR_CTX_PSL2Z, GR_CTX_DIRICHLET_GROUP, GR_CTX_PERM,
     GR_CTX_FEXPR,
+    GR_CTX_DEBUG,
     GR_CTX_UNKNOWN_DOMAIN,
     GR_CTX_WHICH_STRUCTURE_TAB_SIZE
 }
@@ -1516,6 +1517,13 @@ int gr_ctx_cmp_coercion(gr_ctx_t ctx1, gr_ctx_t ctx2);
 
 /* Testing */
 
+#define GR_DEBUG_WRAP                     1
+#define GR_DEBUG_VERBOSE                  2
+#define GR_DEBUG_CHECK_ALWAYS_ABLE        4
+#define GR_DEBUG_TIMING                   8
+
+void gr_ctx_init_debug(gr_ctx_t ctx, gr_ctx_t elem_ctx, int flags, double unable_probability);
+
 #define GR_TEST_VERBOSE 8
 #define GR_TEST_ALWAYS_ABLE 16