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authorPeter Maydell <peter.maydell@linaro.org>2015-01-20 15:19:32 +0000
committerPeter Maydell <peter.maydell@linaro.org>2015-01-20 15:19:32 +0000
commit83ecb22ba2c91a4674ae109595a8ed1da8de4d7a (patch)
tree2491e3feb3edcaa258ba80ff1ee7585cfba538bb
parenta5bd4470ed34b7cf49bda7ea3dcad3a269c99ada (diff)
downloadqemu-arm-83ecb22ba2c91a4674ae109595a8ed1da8de4d7a.tar.gz
scripts/qapi-types.py: Add dummy member to empty structs
Make sure that all generated C structs have at least one field; this avoids potential issues with attempting to malloc space for zero-length structs in C (g_malloc(sizeof struct) would return NULL). It also avoids an incompatibility with C++ (where an empty struct is size 1); that isn't important to us now but might be in future. Generated empty structures look like this: struct Abort { char qapi_dummy_field_for_empty_struct; }; This silences clang warnings like: ./qapi-types.h:3752:1: warning: empty struct has size 0 in C, size 1 in C++ [-Wextern-c-compat] struct Abort ^ Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Eric Blake <eblake@redhat.com> Message-id: 1419359069-16611-1-git-send-email-peter.maydell@linaro.org
-rw-r--r--scripts/qapi-types.py8
1 files changed, 8 insertions, 0 deletions
diff --git a/scripts/qapi-types.py b/scripts/qapi-types.py
index d2f815bca2..1eb272dd26 100644
--- a/scripts/qapi-types.py
+++ b/scripts/qapi-types.py
@@ -99,6 +99,14 @@ struct %(name)s
ret += generate_struct_fields(members)
+ # Make sure that all structs have at least one field; this avoids
+ # potential issues with attempting to malloc space for zero-length structs
+ # in C, and also incompatibility with C++ (where an empty struct is size 1).
+ if not base and not members:
+ ret += mcgen('''
+ char qapi_dummy_field_for_empty_struct;
+''')
+
if len(fieldname):
fieldname = " " + fieldname
ret += mcgen('''