Warnings compiling `test/vis_stress.cpp` with g++ 14 and `-Wextra`

[Paul Hargrove]

When using the newly released GCC 14.1 compilers, builds of the vis_stress test generate numerous -Walloc-size warnings for some len=0 template instantiations in testing with -Wextra.

This is new since GCC 13.2. This is independent of CPU (seen wth both x86_64 and aarch64), code mode, thread mode and network.

==============================================================================
$ /[redacted]/upcxx-inst/bin/upcxx -o vis_stress-seq /[redacted]/upcxx/test/vis_stress.cpp
/[redacted]/upcxx/test/vis_stress.cpp: In instantiation of 'void ops_as_regular::put(const T*, upcxx::global_ptr<T>) [with T = unsigned char; int len = 0]':
/[redacted]/upcxx/test/vis_stress.cpp:116:29:   required from 'void test_case(Ops) [with Uint = unsigned char; int len = 0; Ops = ops_as_regular]'
  116 |   ops.template put<Uint,len>((Uint const*)src_data, nebr_ptr);
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/[redacted]/upcxx/test/vis_stress.cpp:141:22:   required from 'void sweep_given_len() [with Uint = unsigned char; int len = 0]'
  141 |   test_case<Uint,len>(ops_as_regular());
      |   ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
/[redacted]/upcxx/test/vis_stress.cpp:148:26:   required from 'void sweep_given_type() [with Uint = unsigned char]'
  148 |   sweep_given_len<Uint,0>();
      |   ~~~~~~~~~~~~~~~~~~~~~~~^~
/[redacted]/upcxx/test/vis_stress.cpp:163:28:   required from here
  163 |   sweep_given_type<uint8_t>();
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~^~
/[redacted]/upcxx/test/vis_stress.cpp:13:21: warning: allocation of insufficient size '0' for type 'const unsigned char*' with size '8' [-Walloc-size]
   13 |     auto src_ptrs = new T const*[len];
      |                     ^~~~~~~~~~~~~~~~~
/[redacted]/upcxx/test/vis_stress.cpp: In instantiation of 'void ops_as_regular::get(upcxx::global_ptr<T>, T*) [with T = unsigned char; int len = 0]':
/[redacted]/upcxx/test/vis_stress.cpp:126:31:   required from 'void test_case(Ops) [with Uint = unsigned char; int len = 0; Ops = ops_as_regular]'
  126 |     ops.template get<Uint,len>(nebr_ptr, got_data);
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~
/[redacted]/upcxx/test/vis_stress.cpp:141:22:   required from 'void sweep_given_len() [with Uint = unsigned char; int len = 0]'
  141 |   test_case<Uint,len>(ops_as_regular());
      |   ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
/[redacted]/upcxx/test/vis_stress.cpp:148:26:   required from 'void sweep_given_type() [with Uint = unsigned char]'
  148 |   sweep_given_len<Uint,0>();
      |   ~~~~~~~~~~~~~~~~~~~~~~~^~
/[redacted]/upcxx/test/vis_stress.cpp:163:28:   required from here
  163 |   sweep_given_type<uint8_t>();
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~^~
/[redacted]/upcxx/test/vis_stress.cpp:30:22: warning: allocation of insufficient size '0' for type 'unsigned char*' with size '8' [-Walloc-size]
   30 |     auto dest_ptrs = new T*[len];
      |                      ^~~~~~~~~~~
/[redacted]/upcxx/test/vis_stress.cpp: In instantiation of 'void ops_as_regular::put(const T*, upcxx::global_ptr<T>) [with T = short unsigned int; int len = 0]':
/[redacted]/upcxx/test/vis_stress.cpp:116:29:   required from 'void test_case(Ops) [with Uint = short unsigned int; int len = 0; Ops = ops_as_regular]'
  116 |   ops.template put<Uint,len>((Uint const*)src_data, nebr_ptr);
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/[redacted]/upcxx/test/vis_stress.cpp:141:22:   required from 'void sweep_given_len() [with Uint = short unsigned int; int len = 0]'
  141 |   test_case<Uint,len>(ops_as_regular());
      |   ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
/[redacted]/upcxx/test/vis_stress.cpp:148:26:   required from 'void sweep_given_type() [with Uint = short unsigned int]'
  148 |   sweep_given_len<Uint,0>();
      |   ~~~~~~~~~~~~~~~~~~~~~~~^~
/[redacted]/upcxx/test/vis_stress.cpp:164:29:   required from here
  164 |   sweep_given_type<uint16_t>();
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~^~
/[redacted]/upcxx/test/vis_stress.cpp:13:21: warning: allocation of insufficient size '0' for type 'const short unsigned int*' with size '8' [-Walloc-size]
   13 |     auto src_ptrs = new T const*[len];
      |                     ^~~~~~~~~~~~~~~~~
/[redacted]/upcxx/test/vis_stress.cpp: In instantiation of 'void ops_as_regular::get(upcxx::global_ptr<T>, T*) [with T = short unsigned int; int len = 0]':
/[redacted]/upcxx/test/vis_stress.cpp:126:31:   required from 'void test_case(Ops) [with Uint = short unsigned int; int len = 0; Ops = ops_as_regular]'
  126 |     ops.template get<Uint,len>(nebr_ptr, got_data);
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~
/[redacted]/upcxx/test/vis_stress.cpp:141:22:   required from 'void sweep_given_len() [with Uint = short unsigned int; int len = 0]'
  141 |   test_case<Uint,len>(ops_as_regular());
      |   ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
/[redacted]/upcxx/test/vis_stress.cpp:148:26:   required from 'void sweep_given_type() [with Uint = short unsigned int]'
  148 |   sweep_given_len<Uint,0>();
      |   ~~~~~~~~~~~~~~~~~~~~~~~^~
/[redacted]/upcxx/test/vis_stress.cpp:164:29:   required from here
  164 |   sweep_given_type<uint16_t>();
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~^~
/[redacted]/upcxx/test/vis_stress.cpp:30:22: warning: allocation of insufficient size '0' for type 'short unsigned int*' with size '8' [-Walloc-size]
   30 |     auto dest_ptrs = new T*[len];
      |                      ^~~~~~~~~~~
/[redacted]/upcxx/test/vis_stress.cpp: In instantiation of 'void ops_as_regular::put(const T*, upcxx::global_ptr<T>) [with T = unsigned int; int len = 0]':
/[redacted]/upcxx/test/vis_stress.cpp:116:29:   required from 'void test_case(Ops) [with Uint = unsigned int; int len = 0; Ops = ops_as_regular]'
  116 |   ops.template put<Uint,len>((Uint const*)src_data, nebr_ptr);
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/[redacted]/upcxx/test/vis_stress.cpp:141:22:   required from 'void sweep_given_len() [with Uint = unsigned int; int len = 0]'
  141 |   test_case<Uint,len>(ops_as_regular());
      |   ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
/[redacted]/upcxx/test/vis_stress.cpp:148:26:   required from 'void sweep_given_type() [with Uint = unsigned int]'
  148 |   sweep_given_len<Uint,0>();
      |   ~~~~~~~~~~~~~~~~~~~~~~~^~
/[redacted]/upcxx/test/vis_stress.cpp:165:29:   required from here
  165 |   sweep_given_type<uint32_t>();
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~^~
/[redacted]/upcxx/test/vis_stress.cpp:13:21: warning: allocation of insufficient size '0' for type 'const unsigned int*' with size '8' [-Walloc-size]
   13 |     auto src_ptrs = new T const*[len];
      |                     ^~~~~~~~~~~~~~~~~
/[redacted]/upcxx/test/vis_stress.cpp: In instantiation of 'void ops_as_regular::get(upcxx::global_ptr<T>, T*) [with T = unsigned int; int len = 0]':
/[redacted]/upcxx/test/vis_stress.cpp:126:31:   required from 'void test_case(Ops) [with Uint = unsigned int; int len = 0; Ops = ops_as_regular]'
  126 |     ops.template get<Uint,len>(nebr_ptr, got_data);
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~
/[redacted]/upcxx/test/vis_stress.cpp:141:22:   required from 'void sweep_given_len() [with Uint = unsigned int; int len = 0]'
  141 |   test_case<Uint,len>(ops_as_regular());
      |   ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
/[redacted]/upcxx/test/vis_stress.cpp:148:26:   required from 'void sweep_given_type() [with Uint = unsigned int]'
  148 |   sweep_given_len<Uint,0>();
      |   ~~~~~~~~~~~~~~~~~~~~~~~^~
/[redacted]/upcxx/test/vis_stress.cpp:165:29:   required from here
  165 |   sweep_given_type<uint32_t>();
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~^~
/[redacted]/upcxx/test/vis_stress.cpp:30:22: warning: allocation of insufficient size '0' for type 'unsigned int*' with size '8' [-Walloc-size]
   30 |     auto dest_ptrs = new T*[len];
      |                      ^~~~~~~~~~~
/[redacted]/upcxx/test/vis_stress.cpp: In instantiation of 'void ops_as_regular::put(const T*, upcxx::global_ptr<T>) [with T = long unsigned int; int len = 0]':
/[redacted]/upcxx/test/vis_stress.cpp:116:29:   required from 'void test_case(Ops) [with Uint = long unsigned int; int len = 0; Ops = ops_as_regular]'
  116 |   ops.template put<Uint,len>((Uint const*)src_data, nebr_ptr);
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/[redacted]/upcxx/test/vis_stress.cpp:141:22:   required from 'void sweep_given_len() [with Uint = long unsigned int; int len = 0]'
  141 |   test_case<Uint,len>(ops_as_regular());
      |   ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
/[redacted]/upcxx/test/vis_stress.cpp:148:26:   required from 'void sweep_given_type() [with Uint = long unsigned int]'
  148 |   sweep_given_len<Uint,0>();
      |   ~~~~~~~~~~~~~~~~~~~~~~~^~
/[redacted]/upcxx/test/vis_stress.cpp:166:29:   required from here
  166 |   sweep_given_type<uint64_t>();
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~^~
/[redacted]/upcxx/test/vis_stress.cpp:13:21: warning: allocation of insufficient size '0' for type 'const long unsigned int*' with size '8' [-Walloc-size]
   13 |     auto src_ptrs = new T const*[len];
      |                     ^~~~~~~~~~~~~~~~~
/[redacted]/upcxx/test/vis_stress.cpp: In instantiation of 'void ops_as_regular::get(upcxx::global_ptr<T>, T*) [with T = long unsigned int; int len = 0]':
/[redacted]/upcxx/test/vis_stress.cpp:126:31:   required from 'void test_case(Ops) [with Uint = long unsigned int; int len = 0; Ops = ops_as_regular]'
  126 |     ops.template get<Uint,len>(nebr_ptr, got_data);
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~
/[redacted]/upcxx/test/vis_stress.cpp:141:22:   required from 'void sweep_given_len() [with Uint = long unsigned int; int len = 0]'
  141 |   test_case<Uint,len>(ops_as_regular());
      |   ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
/[redacted]/upcxx/test/vis_stress.cpp:148:26:   required from 'void sweep_given_type() [with Uint = long unsigned int]'
  148 |   sweep_given_len<Uint,0>();
      |   ~~~~~~~~~~~~~~~~~~~~~~~^~
/[redacted]/upcxx/test/vis_stress.cpp:166:29:   required from here
  166 |   sweep_given_type<uint64_t>();
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~^~
/[redacted]/upcxx/test/vis_stress.cpp:30:22: warning: allocation of insufficient size '0' for type 'long unsigned int*' with size '8' [-Walloc-size]
   30 |     auto dest_ptrs = new T*[len];
      |                      ^~~~~~~~~~~
==============================================================================

[Paul Hargrove]

The 2-line patch below is sufficient to eliminate the warning, with the test still passing. However, since I do not know if this change is dependent on undefined behavior I include it here rather "for reference" rather than proposing to commit it.

diff --git a/test/vis_stress.cpp b/test/vis_stress.cpp
index 1418fdb..7c87441 100644
--- a/test/vis_stress.cpp
+++ b/test/vis_stress.cpp
@@ -10,7 +10,7 @@ struct ops_as_regular {
   template<typename T, int len>
   void put(T const *src, global_ptr<T> dest) {
     auto dest_ptrs = new global_ptr<T>[len];
-    auto src_ptrs = new T const*[len];
+    auto src_ptrs = len ? new T const*[len] : NULL;

     for(int i=0; i < len; i++) {
       dest_ptrs[i] = dest + i;
@@ -27,7 +27,7 @@ struct ops_as_regular {
   template<typename T, int len>
   void get(global_ptr<T> src, T *dest) {
     auto src_ptrs = new global_ptr<T>[len];
-    auto dest_ptrs = new T*[len];
+    auto dest_ptrs = len ? new T*[len] : NULL;

     for(int i=0; i < len; i++) {
       dest_ptrs[i] = dest + i;