[cmake] WITH_USER_foo properly sandboxes shared libraries

CMakeLists.txt

@@ -366,6 +366,8 @@ function(generate_external_repository_file OUTPUT)
   endif()
 endfunction()
 
+# Symlinks the C++ include path for TARGET as workspace/NAME/include, e.g.
+#  workspace/eigen/include -> .../build/install/include/eigen3
 function(symlink_external_repository_includes NAME TARGET)
   if(ARGN)
     get_target_property(include_dir ${TARGET} INTERFACE_INCLUDE_DIRECTORIES)
@@ -385,6 +387,40 @@ function(symlink_external_repository_includes NAME TARGET)
   endif()
 endfunction()
 
+# Symlinks the C++ libraries for TARGET as workspace/NAME/lib/*, e.g.
+#  workspace/fmt/lib/libfmt.so.6.1.2 -> .../build/install/lib/fmt/libfmt.so.6.1.2
+#  workspace/fmt/lib/libfmt.so.6 -> .../build/install/lib/fmt/libfmt.so.6.1.2
+function(symlink_external_repository_libs NAME TARGET)
+  if(ARGN)
+    foreach(config IN LISTS ARGN)
+      set(workspace "${CMAKE_CURRENT_BINARY_DIR}/external/${config}/workspace")
+      file(MAKE_DIRECTORY "${workspace}/${NAME}/lib")
+      # Link the full library name (i.e., libfmt.so.6.1.2 in the case of shared).
+      get_target_property(location ${TARGET} LOCATION_${config})
+      if(NOT location)
+        message(FATAL_ERROR "Target ${TARGET} has no library in LOCATION_${config}")
+      endif()
+      get_filename_component(basename "${location}" NAME)
+      file(CREATE_LINK "${location}" "${workspace}/${NAME}/lib/${basename}" SYMBOLIC)
+      # Link the SONAME spelling in case of shared libraries.
+      # If the basename does not match this pattern, this part is all a no-op.
+      string(REGEX REPLACE "(\\.so\\.[0-9]+)\\.[0-9]+\\.[0-9]+$" "\\1"
+          other_basename "${basename}")
+      string(REGEX REPLACE "(\\.[0-9]+)\\.[0-9]+\\.[0-9]+\\.dylib$" "\\1.dylib"
+          other_basename "${other_basename}")
+      file(CREATE_LINK "${location}" "${workspace}/${NAME}/lib/${other_basename}" SYMBOLIC)
+    endforeach()
+  else()
+    if(CMAKE_CONFIGURATION_TYPES)
+      symlink_external_repository_libs(${NAME} ${TARGET}
+        ${CMAKE_CONFIGURATION_TYPES})
+    elseif(CMAKE_BUILD_TYPE)
+      symlink_external_repository_libs(${NAME} ${TARGET}
+        ${CMAKE_BUILD_TYPE})
+    endif()
+  endif()
+endfunction()
+
 macro(override_repository NAME)
   set(repo "${CMAKE_CURRENT_BINARY_DIR}/external/$<CONFIG>/workspace/${NAME}")
   list(APPEND BAZEL_OVERRIDE_REPOS --override_repository=${NAME}=${repo})
@@ -412,6 +448,7 @@ if(WITH_USER_FMT)
   find_package(fmt CONFIG REQUIRED)
 
   symlink_external_repository_includes(fmt fmt::fmt)
+  symlink_external_repository_libs(fmt fmt::fmt)
   generate_external_repository_file(fmt/WORKSPACE)
   generate_external_repository_file(
     fmt/BUILD.bazel
@@ -432,6 +469,7 @@ if(WITH_USER_SPDLOG)
   find_package(spdlog CONFIG REQUIRED)
 
   symlink_external_repository_includes(spdlog spdlog::spdlog)
+  symlink_external_repository_libs(spdlog spdlog::spdlog)
   generate_external_repository_file(spdlog/WORKSPACE)
   generate_external_repository_file(
     spdlog/BUILD.bazel

cmake/external/workspace/conversion.bzl

@@ -4,47 +4,9 @@
 # CMake imported targets.
 
 def split_cmake_list(cmake_list_str):
-    """Convert a string containing a CMake-style list into a 'proper' list."""
+    """Converts a string containing a CMake-style list into a 'proper' list.
+    In particular, empty strings remain empty `[]`, not 1-element lists `[""]`.
+    """
     if len(cmake_list_str) == 0:
         return []
     return cmake_list_str.split(";")
-
-def _is_library_extension(ext):
-    """Return True if ext looks like a library extension."""
-    if ext in ["a", "so", "dylib"]:
-        return True
-    if ext.startswith("so."):
-        return True
-    if ext.endswith(".dylib"):
-        return True
-
-    return False
-
-def library_to_linkopts(path):
-    """Convert absolute path to a library to suitable linkopts."""
-    opts = []
-
-    if not path.startswith("/"):
-        fail("{} is not an absolute path.".format(path))
-
-    dirname, libname = path.rsplit("/", 1)
-
-    # Add `-Wl,-rpath,<path>` for `-L<path>`.
-    # See https://github.com/RobotLocomotion/drake/issues/7387#issuecomment-359952616  # noqa
-    opts.append("-Wl,-rpath," + dirname)
-    opts.append("-L" + dirname)
-
-    if "." in libname:
-        ext = libname.split(".", 1)[1]
-    else:
-        ext = ""
-
-    if not _is_library_extension(ext):
-        fail("{} does not appear to be a path to a library.".format(path))
-
-    if not libname.startswith("lib"):
-        fail("Name of library {} must start with `lib`.".format(libname))
-
-    opts.append("-l" + libname[3:].split(".", 1)[0])
-
-    return opts

cmake/external/workspace/fmt/BUILD.bazel.in

@@ -3,27 +3,25 @@
 load("@drake//tools/install:install.bzl", "install")
 load(
     "@drake//:cmake/external/workspace/conversion.bzl",
-    "library_to_linkopts",
     "split_cmake_list",
 )
 
-FMT_DEFINES = split_cmake_list(
+_DEFINES = split_cmake_list(
     "$<TARGET_PROPERTY:fmt::fmt,INTERFACE_COMPILE_DEFINITIONS>",
 )
 
-FMT_LINKOPTS = library_to_linkopts(
-    "$<TARGET_LINKER_FILE:fmt::fmt>",
-)
-
 cc_library(
     name = "fmt",
+    srcs = glob(
+        ["lib/**"],
+        allow_empty = False,
+    ),
     hdrs = glob(
         ["include/**"],
         allow_empty = False,
     ),
-    defines = FMT_DEFINES,
+    defines = _DEFINES,
     includes = ["include"],
-    linkopts = FMT_LINKOPTS,
     visibility = ["//visibility:public"],
 )
 

cmake/external/workspace/spdlog/BUILD.bazel.in

@@ -3,27 +3,26 @@
 load("@drake//tools/install:install.bzl", "install")
 load(
     "@drake//:cmake/external/workspace/conversion.bzl",
-    "library_to_linkopts",
     "split_cmake_list",
 )
 
-SPDLOG_DEFINES = split_cmake_list(
+_DEFINES = split_cmake_list(
     "$<TARGET_PROPERTY:spdlog::spdlog,INTERFACE_COMPILE_DEFINITIONS>",
 )
 
-SPDLOG_LINKOPTS = library_to_linkopts(
-    "$<TARGET_LINKER_FILE:spdlog::spdlog>",
-)
-
 cc_library(
     name = "spdlog",
+    srcs = glob(
+        ["lib/**"],
+        allow_empty = False,
+    ),
     hdrs = glob(
         ["include/**"],
         allow_empty = False,
     ),
-    defines = SPDLOG_DEFINES + ["HAVE_SPDLOG"],
+    defines = _DEFINES + ["HAVE_SPDLOG"],
     includes = ["include"],
-    linkopts = SPDLOG_LINKOPTS + ["-pthread"],
+    linkopts = ["-pthread"],
     visibility = ["//visibility:public"],
     deps = ["@fmt"],
 )