15-11-2006, 12:40 AM
We're wondering if rule 10.1 applies to character constants and the \"plain char\" type, and, if so, what their underlying types are. For example,
From the discussion in 6.10.4, we expect that the underlying types of 'a' and 'abc' are 8 bit signed and 32 bit signed, respectively, on a target with 8 bit chars.
The underlying types of c1 and c2 are less clear. We could treat \"plain char\" similarly to signed char or unsigned char based on the implementation's signedness of \"plain char\", or from the discussion following rules 6.1 and 6.2, we could deduce that \"plain char\" is distinct from signed char and unsigned char with respect to rule 10.1.
If rule 10.1 applies to character constants, we expect that the assignment to c2 violates rule 10.1 because it probably requires a conversion of the character constant to a narrower type. If the \"plain char\" type is unsigned on the target system, the assignment to c1 could be considered as violating rule 10.1 because it requires a conversion from a signed type to an unsigned type.
If the \"plain char\" type is considered distinct from the signed char and unsigned char types, both assignments would violate rule 10.1 unless the underlying type of a character constant is also \"plain char\", though this also seems problematic since, for example, the plain char type usually can't represent the value 'abc'.
What are the Committee's positions on these issues?
Code:
char_t c1 = 'a';
char_t c2 = 'abc';The underlying types of c1 and c2 are less clear. We could treat \"plain char\" similarly to signed char or unsigned char based on the implementation's signedness of \"plain char\", or from the discussion following rules 6.1 and 6.2, we could deduce that \"plain char\" is distinct from signed char and unsigned char with respect to rule 10.1.
If rule 10.1 applies to character constants, we expect that the assignment to c2 violates rule 10.1 because it probably requires a conversion of the character constant to a narrower type. If the \"plain char\" type is unsigned on the target system, the assignment to c1 could be considered as violating rule 10.1 because it requires a conversion from a signed type to an unsigned type.
If the \"plain char\" type is considered distinct from the signed char and unsigned char types, both assignments would violate rule 10.1 unless the underlying type of a character constant is also \"plain char\", though this also seems problematic since, for example, the plain char type usually can't represent the value 'abc'.
What are the Committee's positions on these issues?