Add -Wmacro-use-before-definition

* module/ice-9/boot-9.scm (%auto-compilation-options):
* am/guilec (GUILE_WARNINGS): Add -Wmacro-use-before-definition.
* module/language/tree-il/analyze.scm (unbound-variable-analysis): Use
  match-lambda.
  (<macro-use-info>, macro-use-before-definition-analysis): New
  analysis.
* module/system/base/message.scm (%warning-types): Add
  macro-use-before-definition warning type.
* module/language/tree-il/compile-cps.scm (%warning-passes): Add
  support for macro-use-before-definition.

5 files changed, 81 insertions, 12 deletions

diff --git a/am/guilec b/am/guilec
index 5ef07faa4..7ab9cccb7 100644
--- a/am/guilec
+++ b/am/guilec
@@ -1,7 +1,7 @@
 # -*- makefile -*-
 GOBJECTS = $(SOURCES:%.scm=%.go) $(ELISP_SOURCES:%.el=%.go)
 
-GUILE_WARNINGS = -Wunbound-variable -Warity-mismatch -Wformat
+GUILE_WARNINGS = -Wunbound-variable -Wmacro-use-before-definition -Warity-mismatch -Wformat
 
 moddir = $(pkgdatadir)/$(GUILE_EFFECTIVE_VERSION)/$(modpath)
 nobase_mod_DATA = $(SOURCES) $(ELISP_SOURCES) $(NOCOMP_SOURCES)
diff --git a/module/ice-9/boot-9.scm b/module/ice-9/boot-9.scm
index c2ee108f6..99543e7a5 100644
--- a/module/ice-9/boot-9.scm
+++ b/module/ice-9/boot-9.scm
@@ -3679,8 +3679,8 @@ but it fails to load."
 
 (define %auto-compilation-options
   ;; Default `compile-file' option when auto-compiling.
-  '(#:warnings (unbound-variable arity-mismatch format
-                duplicate-case-datum bad-case-datum)))
+  '(#:warnings (unbound-variable macro-use-before-definition arity-mismatch
+                format duplicate-case-datum bad-case-datum)))
 
 (define* (load-in-vicinity dir file-name #:optional reader)
   "Load source file FILE-NAME in vicinity of directory DIR.  Use a
diff --git a/module/language/tree-il/analyze.scm b/module/language/tree-il/analyze.scm
index 1c0612764..ff4b93d31 100644
--- a/module/language/tree-il/analyze.scm
+++ b/module/language/tree-il/analyze.scm
@@ -35,6 +35,7 @@
             unused-variable-analysis
             unused-toplevel-analysis
             unbound-variable-analysis
+            macro-use-before-definition-analysis
             arity-analysis
             format-analysis))
 
@@ -895,16 +896,77 @@ given `tree-il' element."
 
    (lambda (toplevel env)
      ;; Post-process the result.
-     (vlist-for-each (lambda (name+loc)
-                       (let ((name (car name+loc))
-                             (loc  (cdr name+loc)))
-                         (warning 'unbound-variable loc name)))
+     (vlist-for-each (match-lambda
+                       ((name . loc)
+                        (warning 'unbound-variable loc name)))
                      (vlist-reverse (toplevel-info-refs toplevel))))
 
    (make-toplevel-info vlist-null vlist-null)))
 
 
 ;;;
+;;; Macro use-before-definition analysis.
+;;;
+
+;; <macro-use-info> records are used during tree traversal in search of
+;; possibly uses of macros before they are defined.  They contain a list
+;; of references to top-level variables, and a list of the top-level
+;; macro definitions that have been encountered.  Any definition which
+;; is a macro should in theory be expanded out already; if that's not
+;; the case, the program likely has a bug.
+(define-record-type <macro-use-info>
+  (make-macro-use-info uses defs)
+  macro-use-info?
+  (uses  macro-use-info-uses)  ;; ((VARIABLE-NAME . LOCATION) ...)
+  (defs  macro-use-info-defs))  ;; ((VARIABLE-NAME . LOCATION) ...)
+
+(define macro-use-before-definition-analysis
+  ;; Report possibly unbound variables in the given tree.
+  (make-tree-analysis
+   (lambda (x info env locs)
+     ;; Going down into X.
+     (define (nearest-loc src)
+       (or src (find pair? locs)))
+     (define (add-use name src)
+       (match info
+         (($ <macro-use-info> uses defs)
+          (make-macro-use-info (vhash-consq name src uses) defs))))
+     (define (add-def name src)
+       (match info
+         (($ <macro-use-info> uses defs)
+          (make-macro-use-info uses (vhash-consq name src defs)))))
+     (define (macro? x)
+       (match x
+         (($ <primcall> _ 'make-syntax-transformer) #t)
+         (_ #f)))
+     (match x
+       (($ <toplevel-ref> src name)
+        (add-use name (nearest-loc src)))
+       (($ <toplevel-set> src name)
+        (add-use name (nearest-loc src)))
+       (($ <toplevel-define> src name (? macro?))
+        (add-def name (nearest-loc src)))
+       (_ info)))
+
+   (lambda (x info env locs)
+     ;; Leaving X's scope.
+     info)
+
+   (lambda (info env)
+     ;; Post-process the result.
+     (match info
+       (($ <macro-use-info> uses defs)
+        (vlist-for-each
+         (match-lambda
+           ((name . use-loc)
+            (when (vhash-assq name defs)
+              (warning 'macro-use-before-definition use-loc name))))
+         (vlist-reverse (macro-use-info-uses info))))))
+
+   (make-macro-use-info vlist-null vlist-null)))
+
+
+;;;
 ;;; Arity analysis.
 ;;;
 
diff --git a/module/language/tree-il/compile-cps.scm b/module/language/tree-il/compile-cps.scm
index 3443d761e..9e7dc72ca 100644
--- a/module/language/tree-il/compile-cps.scm
+++ b/module/language/tree-il/compile-cps.scm
@@ -955,11 +955,12 @@ integer."
 (define *comp-module* (make-fluid))
 
 (define %warning-passes
-  `((unused-variable     . ,unused-variable-analysis)
-    (unused-toplevel     . ,unused-toplevel-analysis)
-    (unbound-variable    . ,unbound-variable-analysis)
-    (arity-mismatch      . ,arity-analysis)
-    (format              . ,format-analysis)))
+  `((unused-variable             . ,unused-variable-analysis)
+    (unused-toplevel             . ,unused-toplevel-analysis)
+    (unbound-variable            . ,unbound-variable-analysis)
+    (macro-use-before-definition . ,macro-use-before-definition-analysis)
+    (arity-mismatch              . ,arity-analysis)
+    (format                      . ,format-analysis)))
 
 (define (optimize-tree-il x e opts)
   (define warnings
diff --git a/module/system/base/message.scm b/module/system/base/message.scm
index 26d1a181a..979291c1e 100644
--- a/module/system/base/message.scm
+++ b/module/system/base/message.scm
@@ -115,6 +115,12 @@
                (emit port "~A: warning: possibly unbound variable `~A'~%"
                      loc name)))
 
+           (macro-use-before-definition
+            "report possibly mis-use of macros before they are defined"
+            ,(lambda (port loc name)
+               (emit port "~A: warning: macro `~A' used before definition~%"
+                     loc name)))
+
            (arity-mismatch
             "report procedure arity mismatches (wrong number of arguments)"
             ,(lambda (port loc name certain?)