From 88f0b51312e0a4e3d74c8bf8bee52139705d3d8c Mon Sep 17 00:00:00 2001
From: Ivan Kravets <me@ikravets.com>
Date: Sat, 14 Feb 2015 22:14:49 +0200
Subject: [PATCH] Enable linker "cyclic dependencies" for all platforms

---
 platformio/builder/scripts/atmelavr.py |  3 +--
 platformio/builder/tools/platformio.py | 22 +++++++++++++++-------
 2 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/platformio/builder/scripts/atmelavr.py b/platformio/builder/scripts/atmelavr.py
index ed090862..aa3218d8 100644
--- a/platformio/builder/scripts/atmelavr.py
+++ b/platformio/builder/scripts/atmelavr.py
@@ -55,8 +55,7 @@ env.Replace(
     LINKFLAGS=[
         "-Os",
         "-mmcu=$BOARD_MCU",
-        "-Wl,--gc-sections",
-        "-Wl,--start-group"
+        "-Wl,--gc-sections"
     ],
 
     SIZEPRINTCMD='"$SIZETOOL" --mcu=$BOARD_MCU -C -d $SOURCES',
diff --git a/platformio/builder/tools/platformio.py b/platformio/builder/tools/platformio.py
index 09aba659..15896e6a 100644
--- a/platformio/builder/tools/platformio.py
+++ b/platformio/builder/tools/platformio.py
@@ -43,21 +43,29 @@ def ProcessGeneral(env):
 
 
 def BuildFirmware(env, corelibs):
-    src = env.Clone()
-    vdirs = src.VariantDirRecursive(
+    firmenv = env.Clone()
+    vdirs = firmenv.VariantDirRecursive(
         join("$BUILD_DIR", "src"), join("$PROJECT_DIR", "src"))
 
     # build dependent libs
-    deplibs = src.BuildDependentLibraries(join("$PROJECT_DIR", "src"))
+    deplibs = firmenv.BuildDependentLibraries(join("$PROJECT_DIR", "src"))
+    if deplibs:
+        firmenv.Prepend(
+            _LIBFLAGS="-Wl,--start-group "
+        )
+        firmenv.Append(
+            _LIBFLAGS=" -Wl,--end-group "
+        )
 
-    src.MergeFlags(getenv("PIOSRCBUILD_FLAGS", "$SRCBUILD_FLAGS"))
+    firmenv.MergeFlags(getenv("PIOSRCBUILD_FLAGS", "$SRCBUILD_FLAGS"))
 
-    return src.Program(
+    return firmenv.Program(
         join("$BUILD_DIR", "firmware"),
-        [src.GlobCXXFiles(vdir) for vdir in vdirs],
+        [firmenv.GlobCXXFiles(vdir) for vdir in vdirs],
         LIBS=deplibs + corelibs,
         LIBPATH="$BUILD_DIR",
-        PROGSUFFIX=".elf")
+        PROGSUFFIX=".elf"
+    )
 
 
 def GlobCXXFiles(env, path):