Merge pull request #3183 from stan-dev/makefile/no-implicit-suffixes

Makefile: Disable Make's implict suffix rules

Author: WardBrian

make/compiler_flags

@@ -70,6 +70,13 @@ CXX_VERSION :=  $(shell $(CXX) -dumpfullversion -dumpversion 2>&1)
 CXX_MAJOR := $(word 1,$(subst ., ,$(CXX_VERSION)))
 CXX_MINOR := $(word 2,$(subst ., ,$(CXX_VERSION)))
 
+# disable Make's implicit suffix rules
+# see: https://www.gnu.org/software/make/manual/html_node/Implicit-Rules.html
+# this should make Make slightly faster, as well as avoiding some unexpected
+# behavior when there are other files lying around with the same name as
+# Stan models
+.SUFFIXES: .cpp
+
 ################################################################################
 # Set optional compiler flags for performance
 #

make/libraries

@@ -252,11 +252,8 @@ endif
 ############################################################
 # Google Test:
 #   Build the google test library.
-$(GTEST)/src/gtest-all.o: CXXFLAGS += $(CXXFLAGS_GTEST)
-$(GTEST)/src/gtest-all.o: CPPFLAGS += $(CPPFLAGS_GTEST)
-$(GTEST)/src/gtest-all.o: INC += $(INC_GTEST)
-
-
+$(GTEST)/src/gtest-all.o: $(GTEST)/src/gtest-all.cc
+	$(COMPILE.cpp) -x c++ $(CXXFLAGS_GTEST) $(CPPFLAGS_GTEST) $(INC_GTEST) -o $@ -c $<
 
 ############################################################
 # Clean all libraries