add module testing

Also fix module import

Makefile

@@ -60,13 +60,18 @@ sextest:
 
 SEX_TEST_PROGRAMS = hello-world lists comments unicode
 
+# Multi-module linking is checked end to end; see tests/modules/Makefile.
+check-modules: sexc
+	@$(MAKE) --no-print-directory -C ./tests/modules check SEXC=../../sexc
+
 run-tests: sexc sex-tests sextest
-	./sex-tests && ./sextest --sexc=./sexc $(SEX_TEST_PROGRAMS:%=./tests/sex-programs/%.sex)
+	./sex-tests && ./sextest --sexc=./sexc $(SEX_TEST_PROGRAMS:%=./tests/sex-programs/%.sex) && $(MAKE) check-modules
 
 clean:
 	rm -f $(OBJ) main.o
 	rm -f *.import.scm
 	rm -f *.link
 	rm -f sexc sex-tests sextest
+	$(MAKE) -C ./tests/modules clean
 
-.PHONY: clean run-tests sex-tests sextest
+.PHONY: clean run-tests sex-tests sextest check-modules

sex-modules.scm

@@ -68,11 +68,14 @@
   (case (car form)
     ((pub)
      (case (cadr form)
-       ((fn)                 ; replace with prototype
-        ;; fn type name (arg-list) (body)
-        ;; 1    2   3       4 - we need first 4
-        (cons (copy-form-source! form (take (cdr form) 4)) acc))
-       ((define defmacro import include struct typedef union var)
+       ;; A function is reduced to a prototype and keeps its `pub', so
+       ;; the importing unit declares it with external linkage
+       ((fn)
+        (cons (copy-form-source! form (take form 5)) acc))
+       ;; A variable becomes an `extern' declaration
+       ((var)
+        (cons (copy-form-source! form (cons 'extern (take (cdr form) 3))) acc))
+       ((define defmacro import include struct typedef union)
         (cons (copy-form-source! form (cdr form)) acc))
        (else (sex-error form "pub must be followed by a definition" form))))
     (else acc)))

tests/modules/Makefile

@@ -0,0 +1,28 @@
+# Multi-module linking.
+#
+# Modules are only testable end to end, and nothing else in the suite
+# links more than one translation unit. Three things have to hold at
+# once: an imported `pub fn' comes out as a prototype with external
+# linkage, an imported `pub var' as an extern declaration, and the
+# module's object survives being passed after `--'. Get any of them
+# wrong and this fails to link -- or, in the `pub var' case, links and
+# quietly counts into a private copy.
+
+SEXC ?= ../../sexc
+
+EXPECTED = hello, world\nhello, sex\n2 greetings
+
+check:
+	@$(SEXC) greet.sex -c -o greet.o
+	@$(SEXC) greet-app.sex -o greet-app -- greet.o
+	@if [ "`./greet-app`" = "`printf '$(EXPECTED)\n'`" ]; then \
+		echo "modules ok"; \
+	else \
+		echo "modules FAILED, got:"; ./greet-app; $(MAKE) clean; exit 1; \
+	fi
+	@$(MAKE) --no-print-directory clean
+
+clean:
+	@rm -f greet.o greet-app
+
+.PHONY: check clean

tests/modules/greet-app.sex

@@ -0,0 +1,19 @@
+;;; Uses the greet module. Build both, then link them:
+;;;
+;;;   ./sexc example/greet.sex -c -o greet.o
+;;;   ./sexc example/greet-app.sex -o greet-app -- greet.o
+;;;
+;;; `(import greet)' pastes greet's public declarations here: `greet'
+;;; as a prototype and `greet-count' as an extern. Both keep external
+;;; linkage, so they refer to the one definition in greet.o rather than
+;;; to private copies.
+
+(include stdio.h)
+
+(import greet)
+
+(pub fn main () int
+  (greet "world")
+  (greet "sex")
+  (printf "%d greetings\n" greet-count)
+  (return 0))

tests/modules/greet.sex

@@ -0,0 +1,18 @@
+;;; A module. Everything marked `pub' forms its public interface;
+;;; everything else is private to this file.
+;;;
+;;; Importing a module does not link it: it pastes the declarations, so
+;;; the compiled object still has to be handed to the C compiler. See
+;;; greet-app.sex.
+
+(include stdio.h)
+
+(pub var greet-count int 0)
+
+(pub fn greet ((name (* const char))) void
+  (++ greet-count)
+  (printf "hello, %s\n" name))
+
+;;; Not `pub': invisible to importers, and static in the generated C.
+(fn unused-helper () void
+  (printf "private\n"))