diff --git a/library/core/src/ffi/mod.rs b/library/core/src/ffi/mod.rs index dc107c5d22cdd..2bff42c2517c6 100644 --- a/library/core/src/ffi/mod.rs +++ b/library/core/src/ffi/mod.rs @@ -92,58 +92,76 @@ pub type c_ssize_t = isize; mod c_char_definition { cfg_if! { // These are the targets on which c_char is unsigned. - if #[cfg(any( - all( - target_os = "linux", - any( - target_arch = "aarch64", - target_arch = "arm", - target_arch = "hexagon", - target_arch = "powerpc", - target_arch = "powerpc64", - target_arch = "s390x", - target_arch = "riscv64", - target_arch = "riscv32", - target_arch = "csky" - ) + // These should match the Clang's defaults, except when Clang does not match the ABI's defaults. + // + // aarch64: + // Section 10 "Arm C and C++ language mappings" in Procedure Call Standard for the Arm® + // 64-bit Architecture (AArch64) says C/C++ char is unsigned byte. + // https://github.com/ARM-software/abi-aa/blob/2024Q3/aapcs64/aapcs64.rst#arm-c-and-c-language-mappings + // arm: + // Section 8 "Arm C and C++ Language Mappings" in Procedure Call Standard for the Arm® + // Architecture says C/C++ char is unsigned byte. + // https://github.com/ARM-software/abi-aa/blob/2024Q3/aapcs32/aapcs32.rst#arm-c-and-c-language-mappings + // csky: + // Section 2.1.2 "Primary Data Type" in C-SKY V2 CPU Applications Binary Interface + // Standards Manual says ANSI C char is unsigned byte. + // https://github.com/c-sky/csky-doc/blob/9f7121f7d40970ba5cc0f15716da033db2bb9d07/C-SKY_V2_CPU_Applications_Binary_Interface_Standards_Manual.pdf + // Note: this doesn't seem to match Clang's default (https://github.com/rust-lang/rust/issues/129945). + // hexagon: + // Section 3.1 "Basic data type" in Qualcomm Hexagon™ Application + // Binary Interface User Guide says "By default, the `char` data type is unsigned." + // https://docs.qualcomm.com/bundle/publicresource/80-N2040-23_REV_K_Qualcomm_Hexagon_Application_Binary_Interface_User_Guide.pdf + // msp430: + // Section 2.1 "Basic Types" in MSP430 Embedded Application Binary + // Interface says "The char type is unsigned by default". + // https://www.ti.com/lit/an/slaa534a/slaa534a.pdf + // Note: this doesn't seem to match Clang's default (https://github.com/rust-lang/rust/issues/129945). + // powerpc/powerpc64: + // - PPC32 SysV: "Table 3-1 Scalar Types" in System V Application Binary Interface PowerPC + // Processor Supplement says ANSI C char is unsigned byte + // https://refspecs.linuxfoundation.org/elf/elfspec_ppc.pdf + // - PPC64 ELFv1: Section 3.1.4 "Fundamental Types" in 64-bit PowerPC ELF Application + // Binary Interface Supplement 1.9 says ANSI C is unsigned byte + // https://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi.html#FUND-TYPE + // - PPC64 ELFv2: Section 2.1.2.2 "Fundamental Types" in 64-Bit ELF V2 ABI Specification + // says char is unsigned byte + // https://openpowerfoundation.org/specifications/64bitelfabi/ + // - AIX: XL C for AIX Language Reference says "By default, char behaves like an unsigned char." + // https://www.ibm.com/docs/en/xl-c-aix/13.1.3?topic=specifiers-character-types + // riscv32/riscv64: + // C/C++ type representations section in RISC-V Calling Conventions + // page in RISC-V ELF psABI Document says "char is unsigned." + // https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/draft-20240829-13bfa9f54634cb60d86b9b333e109f077805b4b3/riscv-cc.adoc#cc-type-representations + // s390x: + // - ELF: "Table 1.1.: Scalar types" in ELF Application Binary Interface s390x Supplement + // Version 1.6.1 categorize ISO C char in unsigned integer + // https://github.com/IBM/s390x-abi/releases/tag/v1.6.1 + // - z/OS: XL C/C++ Language Reference says: "By default, char behaves like an unsigned char." + // https://www.ibm.com/docs/en/zos/3.1.0?topic=specifiers-character-types + // + // On the following systems, c_char is signed by default, regardless of architecture. + // Darwin (macOS, iOS, etc.): + // Apple targets' c_char is signed by default even on arm + // https://developer.apple.com/documentation/xcode/writing-arm64-code-for-apple-platforms#Handle-data-types-and-data-alignment-properly + // Windows: + // Windows MSVC C++ Language Reference says "Microsoft-specific: Variables of type char + // are promoted to int as if from type signed char by default, unless the /J compilation + // option is used." + // https://learn.microsoft.com/en-us/cpp/cpp/fundamental-types-cpp?view=msvc-170#character-types) + if #[cfg(all( + not(any(target_vendor = "apple", windows)), + any( + target_arch = "aarch64", + target_arch = "arm", + target_arch = "csky", + target_arch = "hexagon", + target_arch = "msp430", + target_arch = "powerpc", + target_arch = "powerpc64", + target_arch = "riscv32", + target_arch = "riscv64", + target_arch = "s390x", ), - all(target_os = "android", any(target_arch = "aarch64", target_arch = "arm")), - all(target_os = "l4re", target_arch = "x86_64"), - all( - any(target_os = "freebsd", target_os = "openbsd", target_os = "rtems"), - any( - target_arch = "aarch64", - target_arch = "arm", - target_arch = "powerpc", - target_arch = "powerpc64", - target_arch = "riscv64" - ) - ), - all( - target_os = "netbsd", - any( - target_arch = "aarch64", - target_arch = "arm", - target_arch = "powerpc", - target_arch = "riscv64" - ) - ), - all( - target_os = "vxworks", - any( - target_arch = "aarch64", - target_arch = "arm", - target_arch = "powerpc64", - target_arch = "powerpc" - ) - ), - all( - target_os = "fuchsia", - any(target_arch = "aarch64", target_arch = "riscv64") - ), - all(target_os = "nto", target_arch = "aarch64"), - target_os = "horizon", - target_os = "aix", ))] { pub type c_char = u8; } else {