Refactor building DLL example on Windows with windows_dll_library

meteorcloudy · copybara-github · commit c07188a30d8c · 2019-04-15T07:30:51.000-07:00
Closes #7930. PiperOrigin-RevId: 243611901
diff --git a/examples/windows/dll/BUILD b/examples/windows/dll/BUILD
@@ -1,69 +1,35 @@
+load("//examples/windows/dll:windows_dll_library.bzl", "windows_dll_library")
+
 filegroup(
     name = "srcs",
     srcs = glob(["**"]),
     visibility = ["//examples:__pkg__"],
 )
 
-cc_library(
-    name = "hello-library-header",
+# Define the shared library
+windows_dll_library(
+    name = "hellolib",
+    srcs = ["hello-library.cpp"],
     hdrs = ["hello-library.h"],
-)
-
-cc_binary(
-    name = "hellolib.dll",
-    srcs = [
-        "hello-library.cpp",
-    ],
     # Define COMPILING_DLL to export symbols during compiling the DLL.
     # See hello-library.h
     copts = ["/DCOMPILING_DLL"],
-    linkshared = 1,
-    deps = [
-        ":hello-library-header",
-    ],
 )
 
 # **Explicitly link to hellolib.dll**
 
-# Declare hellolib.dll as data dependency and load it explicitly in code.
+## Declare hellolib.dll as data dependency and load it explicitly in code.
 cc_binary(
     name = "hello_world-load-dll-at-runtime",
-    srcs = [
-        "hello_world-load-dll-at-runtime.cpp",
-    ],
+    srcs = ["hello_world-load-dll-at-runtime.cpp"],
     data = [":hellolib.dll"],
 )
 
 # **Implicitly link to hellolib.dll**
 
-# Get the import library for hellolib.dll
-filegroup(
-    name = "hello_lib_import_lib",
-    srcs = [":hellolib.dll"],
-    output_group = "interface_library",
-)
-
-# Because we cannot directly depend on cc_binary from other cc rules in deps attribute,
-# we use cc_import as a bridge to depend on hellolib.dll
-cc_import(
-    name = "hellolib_dll_import",
-    interface_library = ":hello_lib_import_lib",
-    shared_library = ":hellolib.dll",
-)
-
-# Create a new cc_library to also include the headers needed for hellolib.dll
-cc_library(
-    name = "hellolib_dll",
-    deps = [
-        ":hello-library-header",
-        ":hellolib_dll_import",
-    ],
-)
-
+## Link to hellolib.dll through its import library.
 cc_binary(
     name = "hello_world-link-to-dll-via-lib",
-    srcs = [
-        "hello_world-link-to-dll-via-lib.cpp",
-    ],
-    deps = [":hellolib_dll"],
+    srcs = ["hello_world-link-to-dll-via-lib.cpp"],
+    deps = [":hellolib"],
 )
diff --git a/examples/windows/dll/windows_dll_library.bzl b/examples/windows/dll/windows_dll_library.bzl
@@ -0,0 +1,58 @@
+# This is a simple windows_dll_library rule for builing a DLL Windows
+# that can be depended on by other cc rules.
+#
+# Example useage:
+#   windows_dll_library(
+#       name = "hellolib",
+#       srcs = [
+#           "hello-library.cpp",
+#       ],
+#       hdrs = ["hello-library.h"],
+#       # Define COMPILING_DLL to export symbols during compiling the DLL.
+#       copts = ["/DCOMPILING_DLL"],
+#   )
+#
+
+def windows_dll_library(
+        name,
+        srcs = [],
+        hdrs = [],
+        visibility = None,
+        **kwargs):
+    """A simple windows_dll_library rule for builing a DLL Windows."""
+    dll_name = name + ".dll"
+    import_lib_name = name + "_import_lib"
+    import_target_name = name + "_dll_import"
+
+    # Build the shared library
+    native.cc_binary(
+        name = dll_name,
+        srcs = srcs + hdrs,
+        linkshared = 1,
+        **kwargs
+    )
+
+    # Get the import library for the dll
+    native.filegroup(
+        name = import_lib_name,
+        srcs = [":" + dll_name],
+        output_group = "interface_library",
+    )
+
+    # Because we cannot directly depend on cc_binary from other cc rules in deps attribute,
+    # we use cc_import as a bridge to depend on the dll.
+    native.cc_import(
+        name = import_target_name,
+        interface_library = ":" + import_lib_name,
+        shared_library = ":" + dll_name,
+    )
+
+    # Create a new cc_library to also include the headers needed for the shared library
+    native.cc_library(
+        name = name,
+        hdrs = hdrs,
+        visibility = visibility,
+        deps = [
+            ":" + import_target_name,
+        ],
+    )
