Remove dynamic-by-default (#16782)

Dynamic-by-default was a mechanism to automatically select the -dynamic
way for some targets.

It was implemented in a convoluted way: it was defined as a flavour
option, hence it couldn't be passed as a global settings (which are
produced by `configure` before considering flavours), so a build system
rule was used to pass -DDYNAMIC_BY_DEFAULT to the C compiler so that
deriveConstants could infer it.

* Make build system has it disabled for 8 years (951e28c0625ece7e0db6ac9d4a1e61e2737b10de)
* It has never been implemented in Hadrian
* Last time someone tried to enable it 1 year ago it didn't work (!2436)
* Having this as a global constant impedes making GHC multi-target (see !5427)

This commit fully removes support for dynamic-by-default. If someone
wants to reimplement something like this, it would probably need to move
the logic in the compiler.

(Doing this would probably need some refactoring of the way the compiler
handles DynFlags: DynFlags are used to store and to pass enabled ways to
many parts of the compiler. It can be set by command-line flags, GHC
API, global settings. In multi-target GHC, we will use DynFlags to load
the target platform and its constants: but at this point with the
current DynFlags implementation we can't easily update the existing
DynFlags with target-specific options such as dynamic-by-default without
overriding ways previously set by the user.)

5 files changed, 3 insertions, 21 deletions

diff --git a/testsuite/config/ghc b/testsuite/config/ghc
index fa2c9d7c7c..4ecdc5bcb0 100644
--- a/testsuite/config/ghc
+++ b/testsuite/config/ghc
@@ -55,11 +55,8 @@ if ghc_with_threaded_rts:
 if ghc_with_dynamic_rts:
     config.have_shared_libs = True
 
-if config.ghc_dynamic_by_default and config.have_vanilla == 1:
-    config.run_ways.append('static')
-else:
-    if ghc_with_dynamic_rts:
-        config.run_ways.append('dyn')
+if ghc_with_dynamic_rts:
+    config.run_ways.append('dyn')
 
 if (config.have_profiling and ghc_with_threaded_rts):
     config.run_ways.append('profthreaded')
diff --git a/testsuite/mk/ghc-config.hs b/testsuite/mk/ghc-config.hs
index cfd6147cd0..8870a35f80 100644
--- a/testsuite/mk/ghc-config.hs
+++ b/testsuite/mk/ghc-config.hs
@@ -24,7 +24,6 @@ main = do
   getGhcFieldOrFail fields "GhcWithSMP" "Support SMP"
   getGhcFieldOrFail fields "GhcRTSWays" "RTS ways"
   getGhcFieldOrFail fields "GhcLeadingUnderscore" "Leading underscore"
-  getGhcFieldOrDefault fields "GhcDynamicByDefault" "Dynamic by default" "NO"
   getGhcFieldOrDefault fields "GhcDynamic" "GHC Dynamic" "NO"
   getGhcFieldOrDefault fields "GhcProfiled" "GHC Profiled" "NO"
   getGhcFieldProgWithDefault fields "AR" "ar command" "ar"
diff --git a/testsuite/mk/test.mk b/testsuite/mk/test.mk
index a7276207f5..bf0785116d 100644
--- a/testsuite/mk/test.mk
+++ b/testsuite/mk/test.mk
@@ -172,13 +172,7 @@ else
 RUNTEST_OPTS += -e config.have_fast_bignum=True
 endif
 
-ifeq "$(GhcDynamicByDefault)" "YES"
-RUNTEST_OPTS += -e config.ghc_dynamic_by_default=True
-CABAL_MINIMAL_BUILD = --enable-shared --disable-library-vanilla
-else
-RUNTEST_OPTS += -e config.ghc_dynamic_by_default=False
 CABAL_MINIMAL_BUILD = --enable-library-vanilla --disable-shared
-endif
 
 ifeq "$(GhcDynamic)" "YES"
 RUNTEST_OPTS += -e config.ghc_dynamic=True
diff --git a/testsuite/tests/rename/prog006/Makefile b/testsuite/tests/rename/prog006/Makefile
index f7a5f75afe..d2fedd9755 100644
--- a/testsuite/tests/rename/prog006/Makefile
+++ b/testsuite/tests/rename/prog006/Makefile
@@ -18,17 +18,13 @@ include $(TOP)/mk/test.mk
 LOCAL_PKGCONF=local.package.conf
 LOCAL_GHC_PKG = '$(GHC_PKG)' --no-user-package-db -f $(LOCAL_PKGCONF)
 
-ifeq "$(GhcDynamicByDefault)" "YES"
-RM_PROG006_EXTRA_FLAGS = -hisuf dyn_hi -osuf dyn_o
-endif
-
 rn.prog006:
 	rm -f A.hi     A.o     B/C.hi     B/C.o     Main.hi     Main.o
 	rm -f A.dyn_hi A.dyn_o B/C.dyn_hi B/C.dyn_o Main.dyn_hi Main.dyn_o
 	rm -f pkg.conf
 	rm -f pwd pwd.exe pwd.exe.manifest pwd.hi pwd.o
 	'$(TEST_HC)' $(TEST_HC_OPTS) --make pwd -v0
-	'$(TEST_HC)' $(TEST_HC_OPTS) --make -this-unit-id test-1.0-XXX B.C -fforce-recomp -v0 $(RM_PROG006_EXTRA_FLAGS)
+	'$(TEST_HC)' $(TEST_HC_OPTS) --make -this-unit-id test-1.0-XXX B.C -fforce-recomp -v0
 	rm -f pkg.conf
 	echo "name: test" >>pkg.conf
 	echo "version: 1.0" >>pkg.conf
diff --git a/testsuite/tests/safeHaskell/check/pkg01/Makefile b/testsuite/tests/safeHaskell/check/pkg01/Makefile
index ed5185d7e5..283a7df530 100644
--- a/testsuite/tests/safeHaskell/check/pkg01/Makefile
+++ b/testsuite/tests/safeHaskell/check/pkg01/Makefile
@@ -8,11 +8,7 @@ cleanPackageDatabase.%:
 HERE := $(abspath .)
 $(eval $(call canonicalise,HERE))
 
-ifeq "$(GhcDynamicByDefault)" "YES"
-HI_SUF = dyn_hi
-else
 HI_SUF = hi
-endif
 
 mkPackageDatabase.%:
 	$(MAKE) -s --no-print-directory cleanPackageDatabase.$*