duplicates:

• SR-2660 Teach the driver to accept multiple swiftmodules as linker inputs, for static linking

relates to:

• SR-3280 Package manager should link main swiftmodule in executables

Issue Description:

I am not really sure if this a bug or not. Basically I am trying to fix https://bugs.swift.org/browse/SR-3280 by passing swiftmodule file of main executable along with objects in swiftpm's link command.

It works but swift tries to generate a temporary module which makes it want all the search paths again. For example this is what happens on linux:

$ cat main.swift
let str = "Hello world"
print(str)

$ swiftc -module-name foo -g -emit-object -c main.swift
$ swiftc -module-name foo -g -emit-module -emit-module-path foo.swiftmodule main.swift

Now, as per SR-3280, this produces executable but is not debuggable.
$ swiftc -module-name foo -g -o foo -emit-executable main.o
$ lldb foo -o "b main.swift:2" -o r -o "po str" -b

(lldb) po str
error: in auto-import:
failed to get module 'foo' from AST context

Passing swiftmodule makes the executable debuggable as expected:
$ swiftc -module-name foo -g -o foo -emit-executable main.o foo.swiftmodule
$ lldb foo -o "b main.swift:2" -o r -o "po str" -b

(lldb) po str
"Hello world"

But it also generates an intermediate swiftmodule:
$ swiftc -module-name foo -g -o foo -emit-executable main.o foo.swiftmodule -###

/usr/bin/swift-autolink-extract main.o -o /tmp/main-d50a74.autolink
/usr/bin/swift -frontend -emit-module foo.swiftmodule -parse-as-library -target x86_64-unknown-linux-gnu -disable-objc-interop -g -emit-module-doc-path /tmp/foo-0b3cfe.swiftdoc -color-diagnostics -module-name foo -o /tmp/foo-0b3cfe.swiftmodule
/usr/bin/swift -modulewrap /tmp/foo-0b3cfe.swiftmodule -target x86_64-unknown-linux-gnu -o /tmp/foo-429e33.o
/usr/bin/clang++ -fuse-ld=gold -target x86_64-unknown-linux-gnu -Xlinker -rpath -Xlinker /usr/lib/swift/linux /usr/lib/swift/linux/x86_64/swift_begin.o /tmp/foo-429e33.o main.o -L /usr/lib/swift/linux -lswiftCore --target=x86_64-unknown-linux-gnu @/tmp/main-d50a74.autolink /usr/lib/swift/linux/x86_64/swift_end.o -o foo

Shouldn't swift not do that because it already has foo.swiftmodule and run the modulewrap command directly?