shafik added inline comments.
================
Comment at: clang/test/AST/Interp/shifts.cpp:57
+ //c >>= 999999; // expected-warning {{shift count >= width of type}}
+ //c <<= CHAR_BIT; // expected-warning {{shift count >= width of type}}
+ //c >>= CHAR_BIT; // expected-warning {{shift count >= width of type}}
----------------
This is not correct, the operands go through integral promotions first and the
result is the promoted type of the left operand see [dcl.shift
p1](https://eel.is/c++draft/expr.shift#1).
Also see godbolt: https://godbolt.org/z/7qzKjojMb
================
Comment at: clang/test/AST/Interp/shifts.cpp:70
+ i = 1 << (WORD_BIT - 1); // cxx17-warning-not {{sets the sign bit of the
shift expression}}
+ i = -1 << (WORD_BIT - 1); // cxx17-warning {{shifting a negative signed
value is undefined}} \
+ // ref-cxx17-warning {{shifting a negative
signed value is undefined}}
----------------
A negative left operand was made well-formed in C++20 I believe see godbolt:
https://godbolt.org/z/7qzKjojMb
My reference from above for `expr.shift/p1` also applies.
Although a negative right operand is still UB.
Also note shifting into the sign bit was made well-formed in C++11:
https://stackoverflow.com/questions/19593938/is-left-shifting-a-negative-integer-undefined-behavior-in-c11#comment29091986_19593938
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D136532/new/
https://reviews.llvm.org/D136532
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
