(Partial) Merge bitcoin#28629: test: fix usdt undeclared function errors on mantis

4077e43 test: fix usdt undeclared function errors on mantis (willcl-ark)

Pull request description:

  This is one way to fix bitcoin#28600

  Recently usage of undeclared functions became an error rather than a warning, in C2x. https://reviews.llvm.org/D122983?id=420290

  This change has migrated into the build tools of Ubuntu 23.10 which now causes the USDT tests to fail to compile, see
  bitcoin#28600

  I think there are various potential fixes:

  1. Manually declare the functions we use
  2. Fix imports so that manual declarations aren't needed
  3. Revert the new C2X behaviour and don't error on implicit function declarations

  I would have preferred solution 2, but I believe this will require changes to the upstream bcc package. Having played with the imports I can get things working in a standalone C program, using system headers, but when building the program from a python context as we do in the test it uses its own headers (bundled with the python lib) rather than the system ones, and manually importing (some) system headers results in definition mismatches. I also investigated explicitly importing required headers from the package, which use paths like `#import </virtual/bcc/bcc_helpers.h>`, but this seems more obtuse and brittle than simply ignoring the warning.

  Therefore I think that until the upstream python pacakge fixes their declarations, we should fix this by setting `-Wno-error=implicit-function-declaration` for the tracing programs.

  cc maflcko 0xB10C

ACKs for top commit:
  maflcko:
    lgtm ACK 4077e43

Tree-SHA512: 8368bb1155e920a95db128dc893267f8dab64f1ae53f6d63c6d9294e2e4e92bef8515e3697e9113228bedc51c0afdbc5bbcf558c119bf0eb3293dc2ced86b435

Author: fanquake

test/functional/interface_usdt_net.py

@@ -114,7 +114,7 @@ def __repr__(self):
                          fn_name="trace_inbound_message")
         ctx.enable_probe(probe="net:outbound_message",
                          fn_name="trace_outbound_message")
-        bpf = BPF(text=net_tracepoints_program, usdt_contexts=[ctx], debug=0)
+        bpf = BPF(text=net_tracepoints_program, usdt_contexts=[ctx], debug=0, cflags=["-Wno-error=implicit-function-declaration"])
 
         # The handle_* function is a ctypes callback function called from C. When
         # we assert in the handle_* function, the AssertError doesn't propagate

test/functional/interface_usdt_utxocache.py

@@ -177,7 +177,7 @@ def test_uncache(self):
         ctx = USDT(path=str(self.options.bitcoind))
         ctx.enable_probe(probe="utxocache:uncache",
                          fn_name="trace_utxocache_uncache")
-        bpf = BPF(text=utxocache_changes_program, usdt_contexts=[ctx], debug=0)
+        bpf = BPF(text=utxocache_changes_program, usdt_contexts=[ctx], debug=0, cflags=["-Wno-error=implicit-function-declaration"])
 
         # The handle_* function is a ctypes callback function called from C. When
         # we assert in the handle_* function, the AssertError doesn't propagate
@@ -243,7 +243,7 @@ def test_add_spent(self):
         ctx.enable_probe(probe="utxocache:add", fn_name="trace_utxocache_add")
         ctx.enable_probe(probe="utxocache:spent",
                          fn_name="trace_utxocache_spent")
-        bpf = BPF(text=utxocache_changes_program, usdt_contexts=[ctx], debug=0)
+        bpf = BPF(text=utxocache_changes_program, usdt_contexts=[ctx], debug=0, cflags=["-Wno-error=implicit-function-declaration"])
 
         # The handle_* function is a ctypes callback function called from C. When
         # we assert in the handle_* function, the AssertError doesn't propagate
@@ -338,7 +338,7 @@ def test_flush(self):
         ctx = USDT(path=str(self.options.bitcoind))
         ctx.enable_probe(probe="utxocache:flush",
                          fn_name="trace_utxocache_flush")
-        bpf = BPF(text=utxocache_flushes_program, usdt_contexts=[ctx], debug=0)
+        bpf = BPF(text=utxocache_flushes_program, usdt_contexts=[ctx], debug=0, cflags=["-Wno-error=implicit-function-declaration"])
 
         # The handle_* function is a ctypes callback function called from C. When
         # we assert in the handle_* function, the AssertError doesn't propagate

test/functional/interface_usdt_validation.py

@@ -98,7 +98,7 @@ def __repr__(self):
         ctx.enable_probe(probe="validation:block_connected",
                          fn_name="trace_block_connected")
         bpf = BPF(text=validation_blockconnected_program,
-                  usdt_contexts=[ctx], debug=0)
+                  usdt_contexts=[ctx], debug=0, cflags=["-Wno-error=implicit-function-declaration"])
 
         def handle_blockconnected(_, data, __):
             nonlocal expected_blocks, blocks_checked