user32: Ensure at least one character is used in TEXT_WordBreak().

dlls/user32/tests/text.c

@@ -564,6 +564,10 @@ static void test_DrawTextCalcRect(void)
     textheight = DrawTextA(hdc, wordbreak_text, -1, &rect, DT_CALCRECT | DT_WORDBREAK);
     ok(textheight == heightcheck * 2, "Got unexpected textheight %d, expected %d.\n",
        textheight, heightcheck * 2);
+    SetRect(&rect, 0, 0, 1, 1);
+    textheight = DrawTextA(hdc, wordbreak_text, -1, &rect, DT_CALCRECT | DT_WORDBREAK | DT_EDITCONTROL);
+    ok(textheight >= heightcheck * 6, "Got unexpected textheight %d, expected at least %d.\n",
+       textheight, heightcheck * 6);
 
     SetRect(&rect, 0, 0, 1, 1);
     heightcheck = DrawTextW(hdc, wordbreak_textW, -1, &rect, DT_CALCRECT);
@@ -571,6 +575,10 @@ static void test_DrawTextCalcRect(void)
     textheight = DrawTextW(hdc, wordbreak_textW, -1, &rect, DT_CALCRECT | DT_WORDBREAK);
     ok(textheight == heightcheck * 2, "Got unexpected textheight %d, expected %d.\n",
        textheight, heightcheck * 2);
+    SetRect(&rect, 0, 0, 1, 1);
+    textheight = DrawTextW(hdc, wordbreak_textW, -1, &rect, DT_CALCRECT | DT_WORDBREAK | DT_EDITCONTROL);
+    ok(textheight >= heightcheck * 6, "Got unexpected textheight %d, expected at least %d.\n",
+       textheight, heightcheck * 6);
 
     SelectObject(hdc, hOldFont);
     ret = DeleteObject(hFont);

dlls/user32/text.c

@@ -413,8 +413,9 @@ static void TEXT_WordBreak (HDC hdc, WCHAR *str, unsigned int max_str,
             DT_EDITCONTROL)
         {
             /* break the word after the last character that fits (there must be
-             * at least one; none is caught earlier).
-             */
+             * at least one). */
+            if (!chars_fit)
+                ++chars_fit;
             *len_str = chars_fit;
             *chars_used = chars_fit;