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authorEric Blake <eblake@redhat.com>2017-12-01 17:24:32 -0600
committerPaolo Bonzini <pbonzini@redhat.com>2018-01-16 14:54:52 +0100
commit2562755ee78983930d0662fa4d3bc5e2ac166350 (patch)
tree0dd521d04be12d99cabc73ca928c862eabc0c348 /hw/timer/stm32f2xx_timer.c
parent241187c11818e5223c4bdfac79f28fdf63731733 (diff)
downloadfocaccia-qemu-2562755ee78983930d0662fa4d3bc5e2ac166350.tar.gz
focaccia-qemu-2562755ee78983930d0662fa4d3bc5e2ac166350.zip
maint: Fix macros with broken 'do/while(0); ' usage
The point of writing a macro embedded in a 'do { ... } while (0)'
loop (particularly if the macro has multiple statements or would
otherwise end with an 'if' statement) is so that the macro can be
used as a drop-in statement with the caller supplying the
trailing ';'.  Although our coding style frowns on brace-less 'if':
  if (cond)
    statement;
  else
    something else;
that is the classic case where failure to use do/while(0) wrapping
would cause the 'else' to pair with any embedded 'if' in the macro
rather than the intended outer 'if'.  But conversely, if the macro
includes an embedded ';', then the same brace-less coding style
would now have two statements, making the 'else' a syntax error
rather than pairing with the outer 'if'.  Thus, even though our
coding style with required braces is not impacted, ending a macro
with ';' makes our code harder to port to projects that use
brace-less styles.

The change should have no semantic impact.  I was not able to
fully compile-test all of the changes (as some of them are
examples of the ugly bit-rotting debug print statements that are
completely elided by default, and I didn't want to recompile
with the necessary -D witnesses - cleaning those up is left as a
bite-sized task for another day); I did, however, audit that for
all files touched, all callers of the changed macros DID supply
a trailing ';' at the callsite, and did not appear to be used
as part of a brace-less conditional.

Found mechanically via: $ git grep -B1 'while (0);' | grep -A1 \\\\

Signed-off-by: Eric Blake <eblake@redhat.com>
Acked-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20171201232433.25193-7-eblake@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'hw/timer/stm32f2xx_timer.c')
-rw-r--r--hw/timer/stm32f2xx_timer.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/hw/timer/stm32f2xx_timer.c b/hw/timer/stm32f2xx_timer.c
index e5f5e14a90..58fc7b1188 100644
--- a/hw/timer/stm32f2xx_timer.c
+++ b/hw/timer/stm32f2xx_timer.c
@@ -34,7 +34,7 @@
     if (STM_TIMER_ERR_DEBUG >= lvl) { \
         qemu_log("%s: " fmt, __func__, ## args); \
     } \
-} while (0);
+} while (0)
 
 #define DB_PRINT(fmt, args...) DB_PRINT_L(1, fmt, ## args)