add other OS and fix regression in build-exe for freestanding

lib/std/special/start.zig

@@ -32,14 +32,16 @@ comptime {
             if (!@hasDecl(root, "WinMain") and !@hasDecl(root, "WinMainCRTStartup")) {
                 @export("WinMainCRTStartup", WinMainCRTStartup, .Strong);
             }
-        } else if (is_wasm and builtin.os == .freestanding) {
-            if (!@hasDecl(root, "_start")) @export("_start", wasm_freestanding_start, .Strong);
         } else if (builtin.os == .uefi) {
             if (!@hasDecl(root, "EfiMain")) @export("EfiMain", EfiMain, .Strong);
-        } else if (is_mips) {
-            if (!@hasDecl(root, "__start")) @export("__start", _start, .Strong);
-        } else {
-            if (!@hasDecl(root, "_start")) @export("_start", _start, .Strong);
+        } else if (builtin.os != .freestanding) {
+            if (is_mips) {
+                if (!@hasDecl(root, "__start")) @export("__start", _start, .Strong);
+            } else {
+                if (!@hasDecl(root, "_start")) @export("_start", _start, .Strong);
+            }
+        } else if (is_wasm) {
+            if (!@hasDecl(root, "_start")) @export("_start", wasm_freestanding_start, .Strong);
         }
     }
 }

lib/std/target.zig

@@ -46,6 +46,7 @@ pub const Target = union(enum) {
         wasi,
         emscripten,
         uefi,
+        other,
     };
 
     pub const Arch = union(enum) {
@@ -432,6 +433,7 @@ pub const Target = union(enum) {
             .contiki,
             .amdpal,
             .hermit,
+            .other,
             => return .eabi,
             .openbsd,
             .macosx,

src-self-hosted/c_int.zig

@@ -71,7 +71,7 @@ pub const CInt = struct {
     pub fn sizeInBits(cint: CInt, self: Target) u32 {
         const arch = self.getArch();
         switch (self.getOs()) {
-            .freestanding => switch (self.getArch()) {
+            .freestanding, .other => switch (self.getArch()) {
                 .msp430 => switch (cint.id) {
                     .Short,
                     .UShort,

src/target.cpp

@@ -180,6 +180,7 @@ static const Os os_list[] = {
     OsWASI,
     OsEmscripten,
     OsUefi,
+    OsOther,
 };
 
 // Coordinate with zig_llvm.h
@@ -268,6 +269,7 @@ Os target_os_enum(size_t index) {
 ZigLLVM_OSType get_llvm_os_type(Os os_type) {
     switch (os_type) {
         case OsFreestanding:
+        case OsOther:
             return ZigLLVM_UnknownOS;
         case OsAnanas:
             return ZigLLVM_Ananas;
@@ -425,6 +427,8 @@ const char *target_os_name(Os os_type) {
             return "freestanding";
         case OsUefi:
             return "uefi";
+        case OsOther:
+            return "other";
         case OsAnanas:
         case OsCloudABI:
         case OsDragonFly:
@@ -1005,6 +1009,7 @@ uint32_t target_arch_largest_atomic_bits(ZigLLVM_ArchType arch) {
 uint32_t target_c_type_size_in_bits(const ZigTarget *target, CIntType id) {
     switch (target->os) {
         case OsFreestanding:
+        case OsOther:
             switch (target->arch) {
                 case ZigLLVM_msp430:
                     switch (id) {
@@ -1134,7 +1139,8 @@ bool target_allows_addr_zero(const ZigTarget *target) {
 const char *target_o_file_ext(const ZigTarget *target) {
     if (target->abi == ZigLLVM_MSVC ||
         (target->os == OsWindows && !target_abi_is_gnu(target->abi)) ||
-        target->os == OsUefi) {
+        target->os == OsUefi)
+    {
         return ".obj";
     } else {
         return ".o";
@@ -1376,6 +1382,7 @@ const char *target_dynamic_linker(const ZigTarget *target) {
         case OsUefi:
         case OsWindows:
         case OsEmscripten:
+        case OsOther:
             return nullptr;
 
         case OsAnanas:
@@ -1650,6 +1657,7 @@ ZigLLVM_EnvironmentType target_default_abi(ZigLLVM_ArchType arch, Os os) {
         case OsContiki:
         case OsAMDPAL:
         case OsHermitCore:
+        case OsOther:
             return ZigLLVM_EABI;
         case OsOpenBSD:
         case OsMacOSX:

src/target.hpp

@@ -50,6 +50,7 @@ enum Os {
     OsWASI,
     OsEmscripten,
     OsUefi,
+    OsOther,
 };
 
 // Synchronize with target.cpp::subarch_list_list