[vlc-devel] [PATCH] contrib: sidplay2: fix signed char stored as int8_t

[Steve Lhomme]

On 2020-01-11 3:47, Rémi Denis-Courmont wrote:
> Is overflowing conversion to signed type well defined in C++? I'm pretty 
> sure it's implementation-defined in C.

The literal constants are signed by default. The casting from int to 
int8_t is also signed so the values are preserved correctly. (verified 
with gcc and llvm)

> Le 10 janvier 2020 18:54:08 GMT+09:00, Steve Lhomme <robux4 at ycbcr.xyz> a 
> écrit :
> 
>     When using 0xXX notation the issue we also have to adjust the width.
> 
>     Fixes compilation with gcc 9 for Raspberry:
> 
>     compile:  arm-linux-gnueabihf-g++ -DHAVE_CONFIG_H -Icontrib/arm-linux-gnueabihf/include -Icontrib/arm-linux-gnueabihf/include -g -O2 -DHAVE_UNIX -I../../include -I../../include/sidplay -c xsid.cpp -fPIC -DPIC -o xsid.o
>     xsid.cpp:101:1: error: narrowing conversion of ‘'\200'’ from ‘char’ to ‘int8_t’ {aka ‘signed char’} [-Wnarrowing]
>        101 | };
>            | ^
>     xsid.cpp:101:1: error: narrowing conversion of ‘'\224'’ from ‘char’ to ‘int8_t’ {aka ‘signed char’} [-Wnarrowing]
>     xsid.cpp:101:1: error: narrowing conversion of ‘'\251'’ from ‘char’ to ‘int8_t’ {aka ‘signed char’} [-Wnarrowing]
>     xsid.cpp:101:1: error: narrowing conversion of ‘'\274'’ from ‘char’ to ‘int8_t’ {aka ‘signed char’} [-Wnarrowing]
>     xsid.cpp:101:1: error: narrowing conversion of ‘'\316'’ from ‘char’ to ‘int8_t’ {aka ‘signed char’} [-Wnarrowing]
>     xsid.cpp:101:1: error: narrowing conversion of ‘'\341'’ from ‘char’ to ‘int8_t’ {aka ‘signed char’} [-Wnarrowing]
>     xsid.cpp:101:1: error: narrowing conversion of ‘'\362'’ from ‘char’ to ‘int8_t’ {aka ‘signed char’} [-Wnarrowing]
>     make[4]: *** [Makefile:409: xsid.lo] Error 1
>     ------------------------------------------------------------------------
>       contrib/src/sidplay2/rules.mak                |  1 +
>       contrib/src/sidplay2/sidplay2-char-cast.patch | 13 +++++++++++++
>       2 files changed, 14 insertions(+)
>       create mode 100644 contrib/src/sidplay2/sidplay2-char-cast.patch
> 
>     diff --git a/contrib/src/sidplay2/rules.mak b/contrib/src/sidplay2/rules.mak
>     index 84c35ccfee7..de77935774a 100644
>     --- a/contrib/src/sidplay2/rules.mak
>     +++ b/contrib/src/sidplay2/rules.mak
>     @@ -25,6 +25,7 @@ sidplay-libs: sidplay-libs-$(SID_VERSION).tar.gz .sum-sidplay2
>       	$(APPLY) $(SRC)/sidplay2/sidplay2-string.patch
>       	$(APPLY) $(SRC)/sidplay2/sidplay-fix-ln-s.patch
>       	$(APPLY) $(SRC)/sidplay2/sidplay2-resid-dependency.patch
>     +	$(APPLY) $(SRC)/sidplay2/sidplay2-char-cast.patch
>       	$(MOVE)
>       
>       .sidplay2: sidplay-libs
>     diff --git a/contrib/src/sidplay2/sidplay2-char-cast.patch b/contrib/src/sidplay2/sidplay2-char-cast.patch
>     new file mode 100644
>     index 00000000000..14eda139606
>     --- /dev/null
>     +++ b/contrib/src/sidplay2/sidplay2-char-cast.patch
>     @@ -0,0 +1,13 @@
>     +--- sidplay-libs/libsidplay/src/xsid/xsid.cpp.char	2004-06-14 22:08:02.000000000 +0200
>     ++++ sidplay-libs/libsidplay/src/xsid/xsid.cpp	2020-01-10 08:41:49.454974200 +0100
>     +@@ -96,8 +96,8 @@ const int8_t XSID::sampleConvertTable[16
>     + */
>     + const int8_t XSID::sampleConvertTable[16] =
>     + {
>     +-    '\x80', '\x94', '\xa9', '\xbc', '\xce', '\xe1', '\xf2', '\x03',
>     +-    '\x1b', '\x2a', '\x3b', '\x49', '\x58', '\x66', '\x73', '\x7f'
>     ++    (int8_t)0x80, (int8_t)0x94, (int8_t)0xa9, (int8_t)0xbc, (int8_t)0xce, (int8_t)0xe1, (int8_t)0xf2, (int8_t)0x03,
>     ++    (int8_t)0x1b, (int8_t)0x2a, (int8_t)0x3b, (int8_t)0x49, (int8_t)0x58, (int8_t)0x66, (int8_t)0x73, (int8_t)0x7f
>     + };
>     +
>     + const char *XSID::credit =
> 
> 
> -- 
> Envoyé de mon appareil Android avec Courriel K-9 Mail. Veuillez excuser 
> ma brièveté.
> 
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