univalue: avoid warning: array subscript is of type 'char' #4714

pull isghe wants to merge 3 commits into bitcoin:master from isghe:univalue_avoid_wchar_subscripts changing 1 files +8 −8

isghe commented at 3:15 PM on August 17, 2014: contributor

To avoid on: g++ --version Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1 Apple LLVM version 5.1 (clang-503.0.40) (based on LLVM 3.4svn) Target: x86_64-apple-darwin13.3.0 Thread model: posix

the following warnings: CXX univalue/univalue_write.o univalue/univalue_write.cpp:33:12: warning: array subscript is of type 'char' [-Wchar-subscripts] escapes['"'] = "\""; ^~~~ univalue/univalue_write.cpp:34:12: warning: array subscript is of type 'char' [-Wchar-subscripts] escapes[''] = "\"; ^~~~~ univalue/univalue_write.cpp:35:12: warning: array subscript is of type 'char' [-Wchar-subscripts] escapes['/'] = "/"; ^~~~ univalue/univalue_write.cpp:36:12: warning: array subscript is of type 'char' [-Wchar-subscripts] escapes['\b'] = "\b"; ^~~~~ univalue/univalue_write.cpp:37:12: warning: array subscript is of type 'char' [-Wchar-subscripts] escapes['\f'] = "\f"; ^~~~~ univalue/univalue_write.cpp:38:12: warning: array subscript is of type 'char' [-Wchar-subscripts] escapes['\n'] = "\n"; ^~~~~ univalue/univalue_write.cpp:39:12: warning: array subscript is of type 'char' [-Wchar-subscripts] escapes['\r'] = "\r"; ^~~~~ univalue/univalue_write.cpp:40:12: warning: array subscript is of type 'char' [-Wchar-subscripts] escapes['\t'] = "\t"; ^~~~~ 8 warnings generated.
univalue: avoid warning: array subscript is of type 'char' 8cfbd17d51

in src/univalue/univalue_write.cpp:None in 8cfbd17d51 outdated

  21 | -    escapes['\b'] = "\\b";
  22 | -    escapes['\f'] = "\\f";
  23 | -    escapes['\n'] = "\\n";
  24 | -    escapes['\r'] = "\\r";
  25 | -    escapes['\t'] = "\\t";
  26 | +    escapes[static_cast <unsigned char> ('"')] = "\\\"";

sipa commented at 3:35 PM on August 17, 2014:

Can you avoid the spaces before and after < and >?

jgarzik commented at 3:43 PM on August 17, 2014: contributor

Ugh. The compiler is being very dumb here, as the value range is self-evidently known at compile time.

I wonder if a 256-element initializer would do the trick with less ugliness...
univalue: avoid warning: array subscript is of type 'char'
removed extra spaces before and after <>
c356616f41
Merge branch 'univalue_avoid_wchar_subscripts' of https://github.com/isghe/bitcoin into univalue_avoid_wchar_subscripts
Conflicts: src/univalue/univalue_write.cpp
0362aaf525
jgarzik referenced this in commit f30b421531 on Aug 17, 2014
jgarzik commented at 4:20 PM on August 17, 2014: contributor

A better solution is to avoid initializing this array at runtime at every program invocation.
laanwj commented at 7:11 AM on August 18, 2014: member

Right, I understand the reason of this warning. Using chars for array indexes is dangerous as they can be negative. However in this case the exact value is known to the compiler and larger than 0 so it's quite silly...
laanwj commented at 7:19 AM on August 18, 2014: member

Closing in favor of #4715
laanwj closed this on Aug 18, 2014
jgarzik referenced this in commit 3cceba7abb on Aug 18, 2014
reddink referenced this in commit cc589f2ccd on May 27, 2020
MarcoFalke locked this on Sep 8, 2021

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#4715 Univalue: Do not build JSON escape list at runtime