lightningd: fix compilation for older compilers.
What the developer wrote
Authored by Rusty Russell
lightningd: fix compilation for older compilers.
gcc 9.3.0-10 (Ubunto Focal):
```
cc lightningd/offer.c
In file included from ccan/ccan/cast/cast.h:6,
from lightningd/offer.c:2:
lightningd/offer.c: In function 'json_createoffer':
ccan/ccan/cast/cast.h:115:13: error: dereferencing pointer to incomplete type 'struct json_escape'
115 | __typeof__(**(union { int z; __typeof__(expr) x; }){0}.x)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ccan/ccan/build_assert/build_assert.h:38:24: note: in definition of macro 'BUILD_ASSERT_OR_ZERO'
38 | (sizeof(char [1 - 2*!(cond)]) - 1)
| ^~~~
ccan/ccan/cast/cast.h:122:31: note: in expansion of macro 'cast_const_strip2'
122 | __builtin_types_compatible_p(cast_const_strip2(expr), \
| ^~~~~~~~~~~~~~~~~
ccan/ccan/cast/cast.h:59:35: note: in expansion of macro 'cast_const_compat2'
59 | (0 ? BUILD_ASSERT_OR_ZERO(cast_const_compat2((expr), type)) : \
| ^~~~~~~~~~~~~~~~~~
lightningd/offer.c:105:12: note: in expansion of macro 'cast_const2'
105 | cast_const2(const struct json_escape **,
| ^~~~~~~~~~~
ccan/ccan/cast/cast.h:115:13: error: dereferencing pointer to incomplete type 'const struct json_escape'
115 | __typeof__(**(union { int z; __typeof__(expr) x; }){0}.x)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ccan/ccan/build_assert/build_assert.h:38:24: note: in definition of macro 'BUILD_ASSERT_OR_ZERO'
38 | (sizeof(char [1 - 2*!(cond)]) - 1)
| ^~~~
ccan/ccan/cast/cast.h:123:10: note: in expansion of macro 'cast_const_strip2'
123 | cast_const_strip2(type))
| ^~~~~~~~~~~~~~~~~
ccan/ccan/cast/cast.h:59:35: note: in expansion of macro 'cast_const_compat2'
59 | (0 ? BUILD_ASSERT_OR_ZERO(cast_const_compat2((expr), type)) : \
| ^~~~~~~~~~~~~~~~~~
lightningd/offer.c:105:12: note: in expansion of macro 'cast_const2'
105 | cast_const2(const struct json_escape **,
| ^~~~~~~~~~~
make: *** [Makefile:320: lightningd/offer.o] Error 1
```
Reported-by: Shahana
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
What changed, and why it matters
This commit fixes a build failure on older GCC compilers by adding a missing header file. It does not change runtime behavior or fix any security vulnerability.
No security action needed. This is a build-compatibility fix.
Security signals we found
No strong security signals were identified.
Evidence from the diff
The commit adds #include <ccan/json_escape/json_escape.h> to lightningd/offer.c. The cast_const2 macro in ccan/cast/cast.h dereferences a pointer to determine types at compile time, which requires struct json_escape to be a complete type. On Ubuntu Focal’s gcc 9.3.0-10, the incomplete type caused a compilation error. Including the header provides the full definition, allowing the build to succeed. There is no functional code change.
Changed components
lightningd/offer.cInspect captured patch +1 / −0
diff --git a/lightningd/offer.c b/lightningd/offer.c
index dd8871cb..27996281 100644
--- a/lightningd/offer.c
+++ b/lightningd/offer.c
@@ -1,5 +1,6 @@
#include "config.h"
#include <ccan/cast/cast.h>
+#include <ccan/json_escape/json_escape.h> /* Ubuntu focal's gcc needs json_escape defined */
#include <common/bolt12_id.h>
#include <common/bolt12_merkle.h>
#include <common/json_command.h>
Why this scored 15/100
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