Skip building llvm_ext.cc on LLVM 18 or above (#14357)

Makefile

@@ -59,10 +59,9 @@ EXPORTS_BUILD := \
 	CRYSTAL_CONFIG_LIBRARY_PATH=$(CRYSTAL_CONFIG_LIBRARY_PATH)
 SHELL = sh
 LLVM_CONFIG := $(shell src/llvm/ext/find-llvm-config)
-LLVM_VERSION := $(if $(LLVM_CONFIG), $(shell $(LLVM_CONFIG) --version 2> /dev/null))
+LLVM_VERSION := $(if $(LLVM_CONFIG),$(shell $(LLVM_CONFIG) --version 2> /dev/null))
 LLVM_EXT_DIR = src/llvm/ext
 LLVM_EXT_OBJ = $(LLVM_EXT_DIR)/llvm_ext.o
-DEPS = $(LLVM_EXT_OBJ)
 CXXFLAGS += $(if $(debug),-g -O0)
 CRYSTAL_VERSION ?= $(shell cat src/VERSION)
 
@@ -80,6 +79,13 @@ else
   colorize = $(shell printf >&2 "\033[33m$1\033[0m\n")
 endif
 
+DEPS = $(LLVM_EXT_OBJ)
+ifneq ($(LLVM_VERSION),)
+  ifeq ($(shell test $(firstword $(subst ., ,$(LLVM_VERSION))) -ge 18; echo $$?),0)
+    DEPS =
+  endif
+endif
+
 check_llvm_config = $(eval \
 	check_llvm_config := $(if $(LLVM_VERSION),\
 	  $(call colorize,Using $(LLVM_CONFIG) [version=$(LLVM_VERSION)]),\
@@ -208,7 +214,7 @@ $(O)/primitives_spec: $(O)/crystal $(DEPS) $(SOURCES) $(SPEC_SOURCES)
 	@mkdir -p $(O)
 	$(EXPORT_CC) ./bin/crystal build $(FLAGS) $(SPEC_WARNINGS_OFF) -o $@ spec/primitives_spec.cr
 
-$(O)/interpreter_spec: deps $(SOURCES) $(SPEC_SOURCES)
+$(O)/interpreter_spec: $(DEPS) $(SOURCES) $(SPEC_SOURCES)
 	$(eval interpreter=1)
 	@mkdir -p $(O)
 	$(EXPORT_CC) ./bin/crystal build $(FLAGS) $(SPEC_WARNINGS_OFF) -o $@ spec/compiler/interpreter_spec.cr

Makefile.win

@@ -70,7 +70,6 @@ LLVM_CONFIG ?=
 LLVM_VERSION := $(if $(LLVM_CONFIG),$(shell $(LLVM_CONFIG) --version))
 LLVM_EXT_DIR = src\llvm\ext
 LLVM_EXT_OBJ = $(LLVM_EXT_DIR)\llvm_ext.obj
-DEPS = $(LLVM_EXT_OBJ)
 CXXFLAGS += $(if $(static),$(if $(debug),/MTd /Od ,/MT ),$(if $(debug),/MDd /Od ,/MD ))
 CRYSTAL_VERSION ?= $(shell type src\VERSION)
 
@@ -82,6 +81,13 @@ DATADIR ?= $(prefix)
 
 colorize = $1
 
+DEPS = $(LLVM_EXT_OBJ)
+ifneq ($(LLVM_VERSION),)
+  ifeq ($(shell if $(firstword $(subst ., ,$(LLVM_VERSION))) GEQ 18 echo 0),0)
+    DEPS =
+  endif
+endif
+
 check_llvm_config = $(eval \
 	check_llvm_config := $(if $(LLVM_VERSION),\
 		$(info $(call colorize,Using $(LLVM_CONFIG) [version=$(LLVM_VERSION)])),\
@@ -198,7 +204,7 @@ $(O)\primitives_spec.exe: $(O)\crystal.exe $(DEPS) $(SOURCES) $(SPEC_SOURCES)
 	@$(call MKDIR,"$(O)")
 	.\bin\crystal build $(FLAGS) $(SPEC_WARNINGS_OFF) -o "$@" spec\primitives_spec.cr
 
-$(O)\interpreter_spec: deps $(SOURCES) $(SPEC_SOURCES)
+$(O)\interpreter_spec: $(DEPS) $(SOURCES) $(SPEC_SOURCES)
 	$(eval interpreter=1)
 	@$(call MKDIR, "$(O)")
 	.\bin\crystal build $(FLAGS) $(SPEC_WARNINGS_OFF) -o $@ spec\compiler\interpreter_spec.cr