Driver: prevent C++ runtime linkage

lib/Driver/UnixToolChains.cpp

@@ -158,15 +158,29 @@ toolchains::GenericUnix::constructInvocation(const DynamicLinkJobAction &job,
   }
 
   // Configure the toolchain.
-  // By default, use the system clang++ to link.
-  const char *Clang = "clang++";
+  //
+  // By default use the system `clang` to perform the link.  We use `clang` for
+  // the driver here because we do not wish to select a particular C++ runtime.
+  // Furthermore, until C++ interop is enabled, we cannot have a dependency on
+  // C++ code from pure Swift code.  If linked libraries are C++ based, they
+  // should properly link C++.  In the case of static linking, the user can
+  // explicitly specify the C++ runtime to link against.  This is particularly
+  // important for platforms like android where as it is a Linux platform, the
+  // default C++ runtime is `libstdc++` which is unsupported on the target but
+  // as the builds are usually cross-compiled from Linux, libstdc++ is going to
+  // be present.  This results in linking the wrong version of libstdc++
+  // generating invalid binaries.  It is also possible to use different C++
+  // runtimes than the default C++ runtime for the platform (e.g. libc++ on
+  // Windows rather than msvcprt).  When C++ interop is enabled, we will need to
+  // surface this via a driver flag.  For now, opt for the simpler approach of
+  // just using `clang` and avoid a dependency on the C++ runtime.
+  const char *Clang = "clang";
   if (const Arg *A = context.Args.getLastArg(options::OPT_tools_directory)) {
     StringRef toolchainPath(A->getValue());
 
     // If there is a clang in the toolchain folder, use that instead.
-    if (auto toolchainClang =
-            llvm::sys::findProgramByName("clang++", {toolchainPath})) {
-      Clang = context.Args.MakeArgString(toolchainClang.get());
+    if (auto tool = llvm::sys::findProgramByName("clang", {toolchainPath})) {
+      Clang = context.Args.MakeArgString(tool.get());
     }
 
     // Look for binutils in the toolchain folder.

lib/Driver/WindowsToolChains.cpp

@@ -79,15 +79,29 @@ toolchains::Windows::constructInvocation(const DynamicLinkJobAction &job,
   }
 
   // Configure the toolchain.
-  // By default, use the system clang++ to link.
-  const char *Clang = "clang++";
+  //
+  // By default use the system `clang` to perform the link.  We use `clang` for
+  // the driver here because we do not wish to select a particular C++ runtime.
+  // Furthermore, until C++ interop is enabled, we cannot have a dependency on
+  // C++ code from pure Swift code.  If linked libraries are C++ based, they
+  // should properly link C++.  In the case of static linking, the user can
+  // explicitly specify the C++ runtime to link against.  This is particularly
+  // important for platforms like android where as it is a Linux platform, the
+  // default C++ runtime is `libstdc++` which is unsupported on the target but
+  // as the builds are usually cross-compiled from Linux, libstdc++ is going to
+  // be present.  This results in linking the wrong version of libstdc++
+  // generating invalid binaries.  It is also possible to use different C++
+  // runtimes than the default C++ runtime for the platform (e.g. libc++ on
+  // Windows rather than msvcprt).  When C++ interop is enabled, we will need to
+  // surface this via a driver flag.  For now, opt for the simpler approach of
+  // just using `clang` and avoid a dependency on the C++ runtime.
+  const char *Clang = "clang";
   if (const Arg *A = context.Args.getLastArg(options::OPT_tools_directory)) {
     StringRef toolchainPath(A->getValue());
 
     // If there is a clang in the toolchain folder, use that instead.
-    if (auto toolchainClang =
-            llvm::sys::findProgramByName("clang++", {toolchainPath}))
-      Clang = context.Args.MakeArgString(toolchainClang.get());
+    if (auto tool = llvm::sys::findProgramByName("clang", {toolchainPath}))
+      Clang = context.Args.MakeArgString(tool.get());
   }
 
   std::string Target = getTriple().str();

test/Driver/embed-bitcode.swift

@@ -4,12 +4,12 @@
 // CHECK-macho: "ld", inputs: ["[[OBJECT]]"], output: {image: "embed-bitcode"}
 // CHECK-coff: "swiftc.EXE", inputs: ["{{.*}}embed-bitcode.swift"], output: {llvm-bc: "[[BC:.*\.bc]]"}
 // CHECK-coff: "swiftc.EXE", inputs: ["[[BC]]"], output: {object: "[[OBJECT:.*\.o]]"}
-// CHECK-coff: "clang++.exe", inputs: ["[[OBJECT]]"], output: {image: "embed-bitcode"}
+// CHECK-coff: "clang.exe", inputs: ["[[OBJECT]]"], output: {image: "embed-bitcode"}
 
 // CHECK-elf: "swift", inputs: ["{{.*}}embed-bitcode.swift"], output: {llvm-bc: "[[BC:.*\.bc]]"}
 // CHECK-elf: "swift", inputs: ["[[BC]]"], output: {object: "[[OBJECT:.*\.o]]"}
 // CHECK-elf: "swift-autolink-extract", inputs: ["[[OBJECT]]"], output: {autolink: "[[AUTOLINK:.*\.autolink]]"}
-// CHECK-elf: "clang++", inputs: ["[[OBJECT]]", "[[AUTOLINK]]"], output: {image: "main"}
+// CHECK-elf: "clang", inputs: ["[[OBJECT]]", "[[AUTOLINK]]"], output: {image: "main"}
 
 // RUN: %target-swiftc_driver -embed-bitcode %s 2>&1 -### | %FileCheck %s -check-prefix=CHECK-FRONT -check-prefix=CHECK-FRONT-%target-object-format
 // CHECK-FRONT: -frontend

test/Driver/linker-autolink-extract.swift

@@ -6,7 +6,7 @@
 // DEBUG_LINUX-NEXT: bin/swift-autolink-extract
 // DEBUG_LINUX-NEXT: bin/swift
 // DEBUG_LINUX-NEXT: bin/swift -modulewrap
-// DEBUG_LINUX-NEXT: bin/clang++{{"? }}
+// DEBUG_LINUX-NEXT: bin/clang{{"? }}
 // DEBUG_LINUX: -o main
 // DEBUG_LINUX-NOT: dsymutil
 

test/Driver/linker.swift

@@ -147,7 +147,7 @@
 // LINUX-x86_64: swift
 // LINUX-x86_64: -o [[OBJECTFILE:.*]]
 
-// LINUX-x86_64: clang++{{(\.exe)?"? }}
+// LINUX-x86_64: clang{{(\.exe)?"? }}
 // LINUX-x86_64-DAG: -pie
 // LINUX-x86_64-DAG: [[OBJECTFILE]]
 // LINUX-x86_64-DAG: -lswiftCore
@@ -163,7 +163,7 @@
 // LINUX-armv6: swift
 // LINUX-armv6: -o [[OBJECTFILE:.*]]
 
-// LINUX-armv6: clang++{{(\.exe)?"? }}
+// LINUX-armv6: clang{{(\.exe)?"? }}
 // LINUX-armv6-DAG: -pie
 // LINUX-armv6-DAG: [[OBJECTFILE]]
 // LINUX-armv6-DAG: -lswiftCore
@@ -180,7 +180,7 @@
 // LINUX-armv7: swift
 // LINUX-armv7: -o [[OBJECTFILE:.*]]
 
-// LINUX-armv7: clang++{{(\.exe)?"? }}
+// LINUX-armv7: clang{{(\.exe)?"? }}
 // LINUX-armv7-DAG: -pie
 // LINUX-armv7-DAG: [[OBJECTFILE]]
 // LINUX-armv7-DAG: -lswiftCore
@@ -197,7 +197,7 @@
 // LINUX-thumbv7: swift
 // LINUX-thumbv7: -o [[OBJECTFILE:.*]]
 
-// LINUX-thumbv7: clang++{{(\.exe)?"? }}
+// LINUX-thumbv7: clang{{(\.exe)?"? }}
 // LINUX-thumbv7-DAG: -pie
 // LINUX-thumbv7-DAG: [[OBJECTFILE]]
 // LINUX-thumbv7-DAG: -lswiftCore
@@ -214,7 +214,7 @@
 // ANDROID-armv7: swift
 // ANDROID-armv7: -o [[OBJECTFILE:.*]]
 
-// ANDROID-armv7: clang++{{(\.exe)?"? }}
+// ANDROID-armv7: clang{{(\.exe)?"? }}
 // ANDROID-armv7-DAG: -pie
 // ANDROID-armv7-DAG: [[OBJECTFILE]]
 // ANDROID-armv7-DAG: -lswiftCore
@@ -231,7 +231,7 @@
 // CYGWIN-x86_64: swift
 // CYGWIN-x86_64: -o [[OBJECTFILE:.*]]
 
-// CYGWIN-x86_64: clang++{{(\.exe)?"? }}
+// CYGWIN-x86_64: clang{{(\.exe)?"? }}
 // CYGWIN-x86_64-DAG: [[OBJECTFILE]]
 // CYGWIN-x86_64-DAG: -lswiftCore
 // CYGWIN-x86_64-DAG: -L [[STDLIB_PATH:[^ ]+(/|\\\\)lib(/|\\\\)swift]]
@@ -246,7 +246,7 @@
 // WINDOWS-x86_64: swift
 // WINDOWS-x86_64: -o [[OBJECTFILE:.*]]
 
-// WINDOWS-x86_64: clang++{{(\.exe)?"? }}
+// WINDOWS-x86_64: clang{{(\.exe)?"? }}
 // WINDOWS-x86_64-DAG: [[OBJECTFILE]]
 // WINDOWS-x86_64-DAG: -L [[STDLIB_PATH:[^ ]+(/|\\\\)lib(/|\\\\)swift(/|\\\\)windows(/|\\\\)x86_64]]
 // WINDOWS-x86_64-DAG: -F foo -iframework car -F cdr
@@ -272,7 +272,7 @@
 // LINUX_DYNLIB-x86_64: -o [[OBJECTFILE:.*]]
 // LINUX_DYNLIB-x86_64: -o {{"?}}[[AUTOLINKFILE:.*]]
 
-// LINUX_DYNLIB-x86_64: clang++{{(\.exe)?"? }}
+// LINUX_DYNLIB-x86_64: clang{{(\.exe)?"? }}
 // LINUX_DYNLIB-x86_64-DAG: -shared
 // LINUX_DYNLIB-x86_64-DAG: -fuse-ld=gold
 // LINUX_DYNLIB-x86_64-NOT: -pie
@@ -297,7 +297,7 @@
 // LINUX-linker-order: swift
 // LINUX-linker-order: -o [[OBJECTFILE:.*]]
 
-// LINUX-linker-order: clang++{{(\.exe)?"? }}
+// LINUX-linker-order: clang{{(\.exe)?"? }}
 // LINUX-linker-order: -Xlinker -rpath -Xlinker {{[^ ]+(/|\\\\)lib(/|\\\\)swift(/|\\\\)linux}}
 // LINUX-linker-order: -L foo
 // LINUX-linker-order: -Xlinker -rpath -Xlinker customrpath
@@ -306,14 +306,14 @@
 // LINUX-clang-linker-order: swift
 // LINUX-clang-linker-order: -o [[OBJECTFILE:.*]]
 
-// LINUX-clang-linker-order: clang++{{"? }}
+// LINUX-clang-linker-order: clang{{"? }}
 // LINUX-clang-linker-order: -foo foopath
 // LINUX-clang-linker-order: -o {{.*}}
 
 // WINDOWS-clang-linker-order: swift
 // WINDOWS-clang-linker-order: -o [[OBJECTFILE:.*]]
 
-// WINDOWS-clang-linker-order: clang++{{"? }}
+// WINDOWS-clang-linker-order: clang{{"? }}
 // WINDOWS-clang-linker-order: -foo foopath
 // WINDOWS-clang-linker-order: -o {{.*}}
 

test/Driver/modulewrap.swift

@@ -4,4 +4,4 @@
 // CHECK: bin{{/|\\\\}}swift{{c?(\.EXE)?"?}} {{.*}}-emit-module [[MOD]]
 // CHECK-SAME:                                 -o [[MERGED:.*\.swiftmodule]]
 // CHECK: bin{{/|\\\\}}swift{{c?(\.EXE)?"?}} -modulewrap [[MERGED]]{{"?}} -target x86_64-unknown-linux-gnu -o [[OBJ:.*\.o]]
-// CHECK: bin{{/|\\\\}}clang++{{.*}} [[OBJ]]
+// CHECK: bin{{/|\\\\}}clang{{.*}} [[OBJ]]

test/Driver/multi-threaded.swift

@@ -25,27 +25,27 @@
 // MODULE-DAG: -num-threads 4
 // MODULE-DAG: {{[^ ]*[/\\]}}Inputs{{/|\\\\}}main.swift{{"?}} {{[^ ]*[/\\]}}multi-threaded.swift 
 // MODULE-DAG: -o test.swiftmodule
-// MODULE-NOT: {{ld|clang\+\+}}
+// MODULE-NOT: {{ld|clang}}
 
 // ASSEMBLY: -frontend
 // ASSEMBLY-DAG: -num-threads 4
 // ASSEMBLY-DAG: {{[^ ]*[/\\]}}Inputs{{/|\\\\}}main.swift{{"?}} {{[^ ]*[/\\]}}multi-threaded.swift 
 // ASSEMBLY-DAG: -o /build/main.s -o /build/multi-threaded.s
-// ASSEMBLY-NOT: {{ld|clang\+\+}}
+// ASSEMBLY-NOT: {{ld|clang}}
 
 // OBJECT: -frontend
 // OBJECT-DAG: -num-threads 4
 // OBJECT-DAG: {{[^ ]*[/\\]}}Inputs{{/|\\\\}}main.swift{{"?}} {{[^ ]*[/\\]}}multi-threaded.swift 
 // OBJECT-DAG: -o main.o -o multi-threaded.o 
-// OBJECT-NOT: {{ld|clang\+\+}}
+// OBJECT-NOT: {{ld|clang}}
 
 // BITCODE: -frontend
 // BITCODE-DAG: -num-threads 4
 // BITCODE-DAG: {{[^ ]*[/\\]}}Inputs{{/|\\\\}}main.swift{{"?}} {{[^ ]*[/\\]}}multi-threaded.swift 
 // BITCODE-DAG: -o {{.*[/\\]}}main.bc -o {{.*[/\\]}}multi-threaded.bc
 // BITCODE-DAG: -frontend -c -primary-file {{.*[/\\]}}main.bc {{.*}} -o {{[^ ]*}}main.o
 // BITCODE-DAG: -frontend -c -primary-file {{.*[/\\]}}multi-threaded.bc {{.*}} -o {{[^ ]*}}multi-threaded.o
-// BITCODE-NOT: {{ld|clang\+\+}}
+// BITCODE-NOT: {{ld|clang}}
 
 // PARSEABLE: "outputs": [
 // PARSEABLE: "path": "main.o"
@@ -55,7 +55,7 @@
 // EXEC-DAG: -num-threads 4
 // EXEC-DAG: {{[^ ]*[/\\]}}Inputs{{/|\\\\}}main.swift{{"?}} {{[^ ]*[/\\]}}multi-threaded.swift 
 // EXEC-DAG:  -o {{.*te?mp.*[/\\]}}main{{[^ ]*}}.o{{"?}} -o {{.*te?mp.*[/\\]}}multi-threaded{{[^ ]*}}.o
-// EXEC: {{ld|clang\+\+}}
+// EXEC: {{ld|clang}}
 // EXEC:  {{.*te?mp.*[/\\]}}main{{[^ ]*}}.o{{"?}} {{.*te?mp.*[/\\]}}multi-threaded{{[^ ]*}}.o
 
 // DEPENDENCIES-DAG: {{.*}}multi-threaded.o : {{.*[/\\]}}multi-threaded.swift {{.*[/\\]}}Inputs{{[/\\]}}main.swift

test/Driver/parseable_output.swift

@@ -112,8 +112,8 @@
 // CHECK-NEXT: {
 // CHECK-NEXT:   "kind": "began",
 // CHECK-NEXT:   "name": "link",
-// CHECK-NEXT:   "command": "{{.*[\\/](ld|clang\+\+)(\.exe)?(\\")?.*}}parseable_output-[[OUTPUT]].o{{(\\")?}} {{.*}}-o {{.*[\\/]}}parseable_output.swift.tmp.out{{(\\")?}}",
-// CHECK-NEXT:   "command_executable": "{{.*[\\/](ld|clang\+\+)(\.exe)?}}",
+// CHECK-NEXT:   "command": "{{.*[\\/](ld|clang)(\.exe)?(\\")?.*}}parseable_output-[[OUTPUT]].o{{(\\")?}} {{.*}}-o {{.*[\\/]}}parseable_output.swift.tmp.out{{(\\")?}}",
+// CHECK-NEXT:   "command_executable": "{{.*[\\/](ld|clang)(\.exe)?}}",
 // CHECK-NEXT:   "command_arguments": [
 // CHECK:          "{{.*[\\/]}}parseable_output-[[OUTPUT]].o",
 // CHECK:          "-o",

test/Driver/parseable_output_unicode.swift

@@ -114,8 +114,8 @@
 // CHECK-NEXT: {
 // CHECK-NEXT:   "kind": "began",
 // CHECK-NEXT:   "name": "link",
-// CHECK-NEXT:   "command": "{{.*[\\/](ld|clang\+\+.exe)(\\")?}} {{.*[\\/]}}你好-[[OUTPUT]].o{{(\\")?}}{{.*}}-o {{.*[\\/]}}parseable_output_unicode.swift.tmp.out{{(\\")?}}",
-// CHECK-NEXT:   "command_executable": "{{.*[\\/](ld|clang\+\+.exe)(\\")?}}",
+// CHECK-NEXT:   "command": "{{.*[\\/](ld|clang.exe)(\\")?}} {{.*[\\/]}}你好-[[OUTPUT]].o{{(\\")?}}{{.*}}-o {{.*[\\/]}}parseable_output_unicode.swift.tmp.out{{(\\")?}}",
+// CHECK-NEXT:   "command_executable": "{{.*[\\/](ld|clang.exe)(\\")?}}",
 // CHECK-NEXT:   "command_arguments": [
 // CHECK:          "{{.*[\\/]}}你好-[[OUTPUT]].o",
 // CHECK:          "-o",

test/Driver/profiling.swift

@@ -44,11 +44,11 @@
 // watchOS_SIM: {{(bin/)?ld(.exe)?"? }}
 // watchOS_SIM: lib{{(\\\\|/)}}swift{{(\\\\|/)}}clang{{(\\\\|/)}}lib{{(\\\\|/)}}darwin{{(\\\\|/)}}libclang_rt.profile_watchossim.a
 
-// LINUX: clang++{{(\.exe)?"? }}
+// LINUX: clang{{(\.exe)?"? }}
 // LINUX: lib{{(\\\\|/)}}swift{{(\\\\|/)}}clang{{(\\\\|/)}}lib{{(\\\\|/)}}linux{{(\\\\|/)}}libclang_rt.profile-x86_64.a
 // LINUX: -u__llvm_profile_runtime
 
-// WINDOWS: clang++{{(\.exe)?"? }}
+// WINDOWS: clang{{(\.exe)?"? }}
 // WINDOWS: lib{{(\\\\|/)}}swift{{(\\\\|/)}}clang{{(\\\\|/)}}lib{{(\\\\|/)}}windows{{(\\\\|/)}}clang_rt.profile-x86_64.lib
 // WINDOWS: -u__llvm_profile_runtime
 

test/Driver/tools_directory.swift

@@ -1,5 +1,5 @@
 //=================================================
-// ** GENERIC UNIX TARGETS - linking via clang++ **
+// ** GENERIC UNIX TARGETS - linking via clang **
 //=================================================
 
 // RUN: %swiftc_driver -### -target x86_64-linux-unknown -tools-directory %S/Inputs/fake-toolchain %s 2>&1 | %FileCheck -check-prefix CLANGSUB %s
@@ -9,7 +9,7 @@
 // CLANGSUB-SAME: -o [[OBJECTFILE:.*]]
 // CLANGSUB: swift-autolink-extract{{(\.exe)?"?}} [[OBJECTFILE]]
 // CLANGSUB-SAME: -o {{"?}}[[AUTOLINKFILE:.*]]
-// CLANGSUB: {{[^ ]+(\\\\|/)}}Inputs{{/|\\\\}}fake-toolchain{{/|\\\\}}clang++
+// CLANGSUB: {{[^ ]+(\\\\|/)}}Inputs{{/|\\\\}}fake-toolchain{{/|\\\\}}clang
 // CLANGSUB-DAG: [[OBJECTFILE]]
 // CLANGSUB-DAG: @[[AUTOLINKFILE]]
 // CLANGSUB: -o tools_directory
@@ -18,7 +18,7 @@
 // BINUTILS-SAME: -o [[OBJECTFILE:.*]]
 // BINUTILS: swift-autolink-extract{{(\.exe)?"?}} [[OBJECTFILE]]
 // BINUTILS-SAME: -o {{"?}}[[AUTOLINKFILE:.*]]
-// BINUTILS: clang++
+// BINUTILS: clang
 // BINUTILS-DAG: [[OBJECTFILE]]
 // BINUTILS-DAG: @[[AUTOLINKFILE]]
 // BINUTILS-DAG: -B /Something/obviously/fake

test/Driver/verbose.swift

@@ -1,4 +1,4 @@
 // RUN: %swiftc_driver -driver-print-jobs -target x86_64-unknown-linux-gnu -v %s 2>&1 | %FileCheck %s -check-prefix=VERBOSE_CLANG
 // RUN: %swiftc_driver -driver-print-jobs -target x86_64-unknown-windows-msvc -v %s 2>&1 | %FileCheck %s -check-prefix=VERBOSE_CLANG
 
-// VERBOSE_CLANG: clang++{{.*}} -v -o
+// VERBOSE_CLANG: clang{{.*}} -v -o

test/Driver/windows-link-job.swift

@@ -1,4 +1,4 @@
 // RUN: %empty-directory(%t/DISTINCTIVE-WINDOWS-PATH/usr/bin)
 // RUN: %hardlink-or-copy(from: %swift_driver_plain, to: %t/DISTINCTIVE-WINDOWS-PATH/usr/bin/swiftc)
 // RUN: env PATH= %t/DISTINCTIVE-WINDOWS-PATH/usr/bin/swiftc -target x86_64-unknown-windows-msvc -### -module-name link -emit-library %s 2>&1 | %FileCheck %s
-// CHECK: {{^}}clang++
+// CHECK: {{^}}clang

utils/gen-static-stdlib-link-args

@@ -66,6 +66,8 @@ function write_linkfile {
 -latomic
 -lswiftImageInspectionShared
 $ICU_LIBS
+-lstdc++
+-lm
 -Xlinker
 -export-dynamic
 -Xlinker

utils/static-executable-args.lnk

@@ -13,3 +13,5 @@
 -licuuc
 -licudata
 -ldl
+-lstdc++
+-lm