3 files changed, 12 insertions, 4 deletions
diff --git a/c/c.c b/c/c.c
index ab477da..02dbdcb 100644
--- a/c/c.c
+++ b/c/c.c
@@ -9,8 +9,8 @@
 static int
 lexc(struct comp *cm, struct token *tk)
 {
-   struct token tk2;
-   int t = lex(cm->lx, tk);
+   struct token tk2, tk_[1];
+   int t = lex(cm->lx, tk ? tk : tk_);
    if (t == TKSTRLIT && peek(cm, &tk2) == TKSTRLIT && tk2.wide == tk->wide) {
       /* 5.1.1.2 Translation phase 6: concatenate adjacent string literal tokens */
       static char buf[200];
@@ -44,6 +44,13 @@ lexc(struct comp *cm, struct token *tk)
       }
       vfree(&rest);
    }
+   if (in_range(t, TKWBEGIN_, TKWEND_) && (tk = tk ? tk : tk_)->extwarn) {
+      static struct bitset already[BSSIZE(TKWEND_-TKWBEGIN_+1)];
+      if (!bstest(already, t-TKWBEGIN_)) {
+         bsset(already, t-TKWBEGIN_);
+         warn(&tk->span, "%'tk in %M is an extension", tk);
+      }
+   }
    return t;
 }
 #define lex(Cm,Tk) lexc(Cm,Tk)
diff --git a/c/lex.c b/c/lex.c
index afadffc..548f82c 100644
--- a/c/lex.c
+++ b/c/lex.c
@@ -33,6 +33,7 @@ identkeyword(struct token *tk, const char *s, int len)
    };
    int l = 0, h = arraylength(kwtab) - 1, i, cmp;
 
+   tk->extwarn = 0;
    if (len > TKWMAXLEN_) goto ident;
    /* binary search over sorted array */
    while (l <= h) {
@@ -579,8 +580,7 @@ Begin:
          }
          tmp[n] = 0;
          if (!identkeyword(tk, tmp, n) && ccopt.pedant)
-            warn(&(struct span) {{ idx, lx->chridx - idx, lx->fileid }},
-                  "%'tk in %M is an extension", tk);
+            tk->extwarn = 1;
          goto End;
       }
    case 0: if (lx->idx >= lx->ndat) RET(TKEOF);
diff --git a/c/lex.h b/c/lex.h
index fd84f0a..9791340 100644
--- a/c/lex.h
+++ b/c/lex.h
@@ -54,6 +54,7 @@ struct token {
    bool litlit;
    uchar wide : 2; /* for CHRLIT & STRLIT; 1 -> 16bit, 2 -> 32bit */
    uchar wideuni : 1; /* ditto, 0 -> 'L', 1 -> 'u'/'U' (C11) */
+   uchar extwarn : 1; /* warn this keyword token is an extension */
    union {
       uint len;
       struct { ushort macidx, argidx; };