Add a SWIFT_STDLIB_HAS_STDIN flag to compile out the readLine API (for the 'freestanding' preset)

stdlib/CMakeLists.txt

@@ -76,8 +76,12 @@ option(SWIFT_RUNTIME_MACHO_NO_DYLD
        FALSE)
 
 option(SWIFT_STDLIB_HAS_DARWIN_LIBMALLOC
-  "Build stdlib assuming the Darwin build of stdlib can use extended libmalloc APIs"
-  )
+       "Build stdlib assuming the Darwin build of stdlib can use extended libmalloc APIs"
+       TRUE)
+
+option(SWIFT_STDLIB_HAS_STDIN
+       "Build stdlib assuming the platform supports stdin and getline API."
+       TRUE)
 
 option(SWIFT_STDLIB_SINGLE_THREADED_RUNTIME
        "Build the standard libraries assuming that they will be used in an environment with only a single thread."

stdlib/cmake/modules/AddSwiftStdlib.cmake

@@ -329,6 +329,10 @@ function(_add_target_variant_c_compile_flags)
     list(APPEND result "-DSWIFT_STDLIB_HAS_DARWIN_LIBMALLOC=0")
   endif()
 
+  if(SWIFT_STDLIB_HAS_STDIN)
+    list(APPEND result "-DSWIFT_STDLIB_HAS_STDIN")
+  endif()
+
   if(SWIFT_STDLIB_SINGLE_THREADED_RUNTIME)
     list(APPEND result "-DSWIFT_STDLIB_SINGLE_THREADED_RUNTIME")
   endif()

stdlib/cmake/modules/SwiftSource.cmake

@@ -280,6 +280,10 @@ function(_add_target_variant_swift_compile_flags
     list(APPEND result "-D" "SWIFT_RUNTIME_OS_VERSIONING")
   endif()
 
+  if(SWIFT_STDLIB_HAS_STDIN)
+    list(APPEND result "-D" "SWIFT_STDLIB_HAS_STDIN")
+  endif()
+
   set("${result_var_name}" "${result}" PARENT_SCOPE)
 endfunction()
 

stdlib/public/core/InputStream.swift

@@ -12,6 +12,8 @@
 
 import SwiftShims
 
+#if SWIFT_STDLIB_HAS_STDIN
+
 /// Returns a string read from standard input through the end of the current
 /// line or until EOF is reached.
 ///
@@ -42,3 +44,5 @@ public func readLine(strippingNewline: Bool = true) -> String? {
   }
   return result
 }
+
+#endif

stdlib/public/stubs/Stubs.cpp

@@ -202,6 +202,8 @@ uint64_t swift_float80ToString(char *Buffer, size_t BufferLength,
 }
 #endif
 
+#if SWIFT_STDLIB_HAS_STDIN
+
 /// \param[out] LinePtr Replaced with the pointer to the malloc()-allocated
 /// line.  Can be NULL if no characters were read. This buffer should be
 /// freed by the caller.
@@ -265,6 +267,8 @@ swift_stdlib_readLine_stdin(unsigned char **LinePtr) {
 #endif
 }
 
+#endif  // SWIFT_STDLIB_HAS_STDIN
+
 static bool swift_stringIsSignalingNaN(const char *nptr) {
   if (nptr[0] == '+' || nptr[0] == '-') {
     ++nptr;

test/stdlib/InputStream.swift.gyb

@@ -12,6 +12,7 @@
 // -*- swift -*-
 // RUN: %target-run-simple-swiftgyb
 // REQUIRES: executable_test
+// UNSUPPORTED: freestanding
 
 import StdlibUnittest
 

utils/build-presets.ini

@@ -2455,6 +2455,7 @@ swift-enable-compatibility-overrides=0
 swift-enable-reflection=0
 swift-runtime-macho-no-dyld=1
 swift-stdlib-has-darwin-libmalloc=0
+swift-stdlib-has-stdin=0
 swift-stdlib-single-threaded-runtime=1
 swift-stdlib-os-versioning=0
 extra-cmake-options=

utils/build-script-impl

@@ -210,6 +210,7 @@ KNOWN_SETTINGS=(
     swift-stdlib-os-versioning                    "1"               "whether to build stdlib with availability based on OS versions (Darwin only)"
     swift-stdlib-stable-abi                       ""                "should stdlib be built with stable ABI, if not set defaults to true on Darwin, false otherwise"
     swift-stdlib-has-darwin-libmalloc             "1"               "whether the Darwin build of stdlib can use extended libmalloc APIs"
+    swift-stdlib-has-stdin                        "1"               "whether to build stdlib assuming the platform supports stdin and getline API"
     swift-disable-dead-stripping                  "0"               "turns off Darwin-specific dead stripping for Swift host tools"
     common-swift-flags                            ""                "Flags used for Swift targets other than the stdlib, like the corelibs"
 
@@ -1970,6 +1971,7 @@ for host in "${ALL_HOSTS[@]}"; do
                     -DSWIFT_RUNTIME_MACHO_NO_DYLD:BOOL=$(true_false "${SWIFT_RUNTIME_MACHO_NO_DYLD}")
                     -DSWIFT_STDLIB_OS_VERSIONING:BOOL=$(true_false "${SWIFT_STDLIB_OS_VERSIONING}")
                     -DSWIFT_STDLIB_HAS_DARWIN_LIBMALLOC:BOOL=$(true_false "${SWIFT_STDLIB_HAS_DARWIN_LIBMALLOC}")
+                    -DSWIFT_STDLIB_HAS_STDIN:BOOL=$(true_false "${SWIFT_STDLIB_HAS_STDIN}")
                     -DSWIFT_NATIVE_LLVM_TOOLS_PATH:STRING="${native_llvm_tools_path}"
                     -DSWIFT_NATIVE_CLANG_TOOLS_PATH:STRING="${native_clang_tools_path}"
                     -DSWIFT_NATIVE_SWIFT_TOOLS_PATH:STRING="${native_swift_tools_path}"