[NaCl SDK] Print nice error if host build can't find gcc or cl.exe

native_client_sdk/src/tools/common.mk

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 #
 # GNU Make based build file.  For details on GNU Make see:
 #   http://www.gnu.org/software/make/manual/make.html
 #
 #
 
@@ skipping 51 matching lines @@
 export CYGWIN
 
 
 #
 # Alias for standard POSIX file system commands
 #
 CP:=python $(NACL_SDK_ROOT)/tools/oshelpers.py cp
 MKDIR:=python $(NACL_SDK_ROOT)/tools/oshelpers.py mkdir
 MV:=python $(NACL_SDK_ROOT)/tools/oshelpers.py mv
 RM:=python $(NACL_SDK_ROOT)/tools/oshelpers.py rm
+WHICH:=python $(NACL_SDK_ROOT)/tools/oshelpers.py which
 
 
 #
 # Compute path to requested NaCl Toolchain
 #
 OSNAME:=$(shell python $(NACL_SDK_ROOT)/tools/getos.py)
 TC_PATH:=$(abspath $(NACL_SDK_ROOT)/toolchain)
 
 
 
@@ skipping 107 matching lines @@
 #
 # If the requested toolchain is a NaCl or PNaCl toolchain, the use the
 # macros and targets defined in nacl.mk, otherwise use the host sepecific
 # macros and targets.
 #
 ifneq (,$(findstring $(TOOLCHAIN),linux mac))
 include $(NACL_SDK_ROOT)/tools/host_gcc.mk
 endif
 
 ifneq (,$(findstring $(TOOLCHAIN),win))
+ifneq (,$(findstring $(shell $(WHICH) cl.exe),cl.exe))

[noelallen1, 2013/02/08 23:50:06]

nit:  I would have put the WIN specific stuff in host_vc as much as possible.

 include $(NACL_SDK_ROOT)/tools/host_vc.mk
+else
+$(warning cl.exe not found in PATH. Skipping host build.)
+endif
 endif
 
 ifneq (,$(findstring $(TOOLCHAIN),glibc newlib))
 include $(NACL_SDK_ROOT)/tools/nacl_gcc.mk
 endif
 
 ifneq (,$(findstring $(TOOLCHAIN),pnacl))
 include $(NACL_SDK_ROOT)/tools/nacl_llvm.mk
 endif
 
@@ skipping 46 matching lines @@
 
 SYSARCH=$(shell python $(NACL_SDK_ROOT)/tools/getos.py --chrome)
 GDB_ARGS+=-D $(TC_PATH)/$(OSNAME)_x86_$(TOOLCHAIN)/bin/$(SYSARCH)-nacl-gdb
 GDB_ARGS+=-D $(CURDIR)/$(OUTDIR)/$(TARGET)_$(SYSARCH).nexe
 
 DEBUG: CHECK_FOR_CHROME all
         $(RUN_PY) $(GDB_ARGS) \
             -C $(CURDIR) -P $(PAGE) $(addprefix -E ,$(CHROME_ENV)) -- \
             $(CHROME_PATH) $(CHROME_ARGS) --enable-nacl-debug \
             --register-pepper-plugins="$(PPAPI_DEBUG),$(PPAPI_RELEASE)"