From 3b08f774e7938928e3a240a47a0a7554cdc8d50b Mon Sep 17 00:00:00 2001
From: Yun Peng <pcloudy@google.com>
Date: Thu, 4 May 2017 06:17:42 -0400
Subject: Adding feature for linking C Run-Time library on Windows

By default, we use /MT(/MTd for debug mode) and link to
libcmt.lib(libcmtd.lib).

Users can set USE_DYNAMIC_CRT=1 or add --action_env=USE_DYNAMIC_CRT=1 to
switch to /MD and msvcrt.lib (/MDd and msvcrtd.lib for debug mode)

Reference: https://msdn.microsoft.com/en-us/library/abx4dbyh.aspx

Fixed https://github.com/bazelbuild/bazel/issues/2120

Change-Id: I61e65ace82163acd456bf82f2b108c5fe8d8a8ce
PiperOrigin-RevId: 155850886
---
 tools/cpp/CROSSTOOL.tpl    | 47 ++++++++++++++++++++++++++++++++++++++++++++++
 tools/cpp/cc_configure.bzl | 31 ++++++++++++++++++++++++++++++
 2 files changed, 78 insertions(+)

diff --git a/tools/cpp/CROSSTOOL.tpl b/tools/cpp/CROSSTOOL.tpl
index f4f0f36834..64234625d9 100644
--- a/tools/cpp/CROSSTOOL.tpl
+++ b/tools/cpp/CROSSTOOL.tpl
@@ -712,6 +712,50 @@ toolchain {
     }
   }
 
+  feature {
+    name: 'link_crt_library'
+    flag_set {
+      action: 'c-compile'
+      action: 'c++-compile'
+      flag_group {
+        # The flag is filled by cc_configure.
+        # The default option is /MT, set USE_DYNAMIC_CRT=1 to change it to /MD
+        flag: "%{crt_option}"
+      }
+    }
+    flag_set {
+      action: 'c++-link-executable'
+      action: 'c++-link-dynamic-library'
+      flag_group {
+      # The flag is filled by cc_configure.
+        # The default value is libcmt.lib, set USE_DYNAMIC_CRT=1 to change it to msvcrt.lib
+        flag: "/DEFAULTLIB:%{crt_library}"
+      }
+    }
+  }
+
+  feature {
+    name: 'link_crt_debug_library'
+    flag_set {
+      action: 'c-compile'
+      action: 'c++-compile'
+      flag_group {
+        # The flag is filled by cc_configure.
+        # The default option is /MTd, set USE_DYNAMIC_CRT=1 to change it to /MDd
+        flag: "%{crt_debug_option}"
+      }
+    }
+    flag_set {
+      action: 'c++-link-executable'
+      action: 'c++-link-dynamic-library'
+      flag_group {
+        # The flag is filled by cc_configure.
+        # The default value is libcmtd.lib, set USE_DYNAMIC_CRT=1 to change it to msvcrtd.lib
+        flag: "/DEFAULTLIB:%{crt_debug_library}"
+      }
+    }
+  }
+
   feature {
     name: 'dbg'
     flag_set {
@@ -734,6 +778,7 @@ toolchain {
         flag: "/INCREMENTAL:NO"
       }
     }
+    implies: 'link_crt_debug_library'
     implies: 'generate_pdb_file'
   }
 
@@ -755,6 +800,7 @@ toolchain {
         flag: "/INCREMENTAL:NO"
       }
     }
+    implies: 'link_crt_library'
     implies: 'generate_pdb_file'
   }
 
@@ -767,6 +813,7 @@ toolchain {
         flag: "/O2"
       }
     }
+    implies: 'link_crt_library'
   }
 
   compilation_mode_flags {
diff --git a/tools/cpp/cc_configure.bzl b/tools/cpp/cc_configure.bzl
index 4f93195d26..e4427cd77a 100644
--- a/tools/cpp/cc_configure.bzl
+++ b/tools/cpp/cc_configure.bzl
@@ -607,6 +607,28 @@ def _is_support_whole_archive(repository_ctx, vc_path):
   result = _execute(repository_ctx, [linker], expect_failure = True)
   return result.find("/WHOLEARCHIVE") != -1
 
+def _is_using_dynamic_crt(repository_ctx):
+  """Returns True if USE_DYNAMIC_CRT is set to 1."""
+  env = repository_ctx.os.environ
+  return "USE_DYNAMIC_CRT" in env and env["USE_DYNAMIC_CRT"] == "1"
+
+def _get_crt_option(repository_ctx, debug = False):
+  """Get the CRT option, default is /MT and /MTd."""
+  crt_option = "/MT"
+  if _is_using_dynamic_crt(repository_ctx):
+    crt_option = "/MD"
+  if debug:
+    crt_option += "d"
+  return crt_option
+
+def _get_crt_library(repository_ctx, debug = False):
+  """Get the CRT library to link, default is libcmt.lib and libcmtd.lib."""
+  crt_library = "libcmt"
+  if _is_using_dynamic_crt(repository_ctx):
+    crt_library = "msvcrt"
+  if debug:
+    crt_library += "d"
+  return crt_library + ".lib"
 
 def _escaped_cuda_compute_capabilities(repository_ctx):
   """Returns a %-escaped list of strings representing cuda compute capabilities."""
@@ -768,6 +790,10 @@ def _impl(repository_ctx):
         "%{msvc_env_include}": escaped_include_paths,
         "%{msvc_env_lib}": escaped_lib_paths,
         "%{content}": _get_escaped_windows_msys_crosstool_content(repository_ctx),
+        "%{crt_option}": _get_crt_option(repository_ctx),
+        "%{crt_debug_option}": _get_crt_option(repository_ctx, debug=True),
+        "%{crt_library}": _get_crt_library(repository_ctx),
+        "%{crt_debug_library}": _get_crt_library(repository_ctx, debug=True),
         "%{opt_content}": "",
         "%{dbg_content}": "",
         "%{cxx_builtin_include_directory}": "\n".join(escaped_cxx_include_directories),
@@ -841,6 +867,10 @@ def _impl(repository_ctx):
           "%{msvc_env_path}": "",
           "%{msvc_env_include}": "",
           "%{msvc_env_lib}": "",
+          "%{crt_option}": "",
+          "%{crt_debug_option}": "",
+          "%{crt_library}": "",
+          "%{crt_debug_library}": "",
       })
 
 cc_autoconf = repository_rule(
@@ -864,6 +894,7 @@ cc_autoconf = repository_rule(
         "CUDA_PATH",
         "HOMEBREW_RUBY_PATH",
         "NO_WHOLE_ARCHIVE_OPTION",
+        "USE_DYNAMIC_CRT",
         "SYSTEMROOT",
         "VS90COMNTOOLS",
         "VS100COMNTOOLS",
-- 
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