Fix #9243 so recompilation avoidance works with -fno-code

Summary:
Where we track timestamps of object files, also track timestamps
for interface files.  When -fno-code -fwrite-interface is enabled, use
the interface file timestamp as an extra check to see if the files are
up-to-date.  We had to apply this logic to one-shot and make modes.

This fix would be good to merge into 7.10; it makes using -fno-code
-fwrite-interface for flywheel type checking usable.

Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>

Test Plan: validate and new test cases

Reviewers: austin

Subscribers: carter, thomie

Differential Revision: https://phabricator.haskell.org/D596

GHC Trac Issues: #9243

8 files changed, 54 insertions, 0 deletions

diff --git a/testsuite/tests/driver/retc001/A.hs b/testsuite/tests/driver/retc001/A.hs
new file mode 100644
index 0000000000..d7fc96e70e
--- /dev/null
+++ b/testsuite/tests/driver/retc001/A.hs
@@ -0,0 +1,4 @@
+module A where
+
+foo :: Int
+foo = 4
diff --git a/testsuite/tests/driver/retc001/B1.hs b/testsuite/tests/driver/retc001/B1.hs
new file mode 100644
index 0000000000..d0efd79bf0
--- /dev/null
+++ b/testsuite/tests/driver/retc001/B1.hs
@@ -0,0 +1,3 @@
+module B (foo) where
+
+import A (foo)
diff --git a/testsuite/tests/driver/retc001/B2.hs b/testsuite/tests/driver/retc001/B2.hs
new file mode 100644
index 0000000000..213d77d5eb
--- /dev/null
+++ b/testsuite/tests/driver/retc001/B2.hs
@@ -0,0 +1,3 @@
+module B () where
+
+import A ()
diff --git a/testsuite/tests/driver/retc001/C.hs b/testsuite/tests/driver/retc001/C.hs
new file mode 100644
index 0000000000..d38b2ff51c
--- /dev/null
+++ b/testsuite/tests/driver/retc001/C.hs
@@ -0,0 +1,6 @@
+module Main (main) where
+
+import B (foo)
+
+main :: IO ()
+main = print foo
diff --git a/testsuite/tests/driver/retc001/Makefile b/testsuite/tests/driver/retc001/Makefile
new file mode 100644
index 0000000000..a3cf6ebf3d
--- /dev/null
+++ b/testsuite/tests/driver/retc001/Makefile
@@ -0,0 +1,24 @@
+TOP=../../..
+include $(TOP)/mk/boilerplate.mk
+include $(TOP)/mk/test.mk
+
+# -fforce-recomp makes lots of driver tests trivially pass, so we
+# filter it out from $(TEST_HC_OPTS).
+TEST_HC_OPTS_NO_RECOMP = $(filter-out -fforce-recomp,$(TEST_HC_OPTS))
+
+# Recompilation tests
+
+clean:
+	rm -f *.o *.hi
+	rm -f B.hs C
+
+# 001: removing an export should force a retypecheck of dependent modules.
+
+retc001: clean
+	cp B1.hs B.hs
+	'$(TEST_HC)' $(TEST_HC_OPTS_NO_RECOMP) -fno-code -fwrite-interface --make C.hs
+	echo 'Middle'
+	'$(TEST_HC)' $(TEST_HC_OPTS_NO_RECOMP) -fno-code -fwrite-interface --make C.hs
+	echo 'End'
+	cp B2.hs B.hs
+	-'$(TEST_HC)' $(TEST_HC_OPTS_NO_RECOMP) -fno-code -fwrite-interface --make C.hs
diff --git a/testsuite/tests/driver/retc001/all.T b/testsuite/tests/driver/retc001/all.T
new file mode 100644
index 0000000000..7e5fda589c
--- /dev/null
+++ b/testsuite/tests/driver/retc001/all.T
@@ -0,0 +1,5 @@
+test('retc001',
+     [clean_cmd('$MAKE -s clean')],
+     run_command,
+     ['$MAKE -s --no-print-directory retc001'])
+
diff --git a/testsuite/tests/driver/retc001/retc001.stderr b/testsuite/tests/driver/retc001/retc001.stderr
new file mode 100644
index 0000000000..724326e081
--- /dev/null
+++ b/testsuite/tests/driver/retc001/retc001.stderr
@@ -0,0 +1,2 @@
+
+C.hs:3:11: Module ‘B’ does not export ‘foo’
diff --git a/testsuite/tests/driver/retc001/retc001.stdout b/testsuite/tests/driver/retc001/retc001.stdout
new file mode 100644
index 0000000000..381850d9a4
--- /dev/null
+++ b/testsuite/tests/driver/retc001/retc001.stdout
@@ -0,0 +1,7 @@
+[1 of 3] Compiling A                ( A.hs, nothing )
+[2 of 3] Compiling B                ( B.hs, nothing )
+[3 of 3] Compiling Main             ( C.hs, nothing )
+Middle
+End
+[2 of 3] Compiling B                ( B.hs, nothing )
+[3 of 3] Compiling Main             ( C.hs, nothing ) [B changed]