master abb43a62365 1/2: Stop pretending that specpdl overflow can ever occur

[Mattias Engdegård]

branch: master
commit abb43a62365b378b27a85456db42dfa34d2ad760
Author: Mattias Engdegård <mattiase@acm.org>
Commit: Mattias Engdegård <mattiase@acm.org>

    Stop pretending that specpdl overflow can ever occur
    
    * src/eval.c (grow_specpdl_allocation): Remove impossible error.
    * src/data.c (syms_of_data): Note obsolence of
    `excessive-variable-binding`.
---
 src/data.c | 5 +++--
 src/eval.c | 3 +--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/data.c b/src/data.c
index 8dc5000424e..4ab37e86ce5 100644
--- a/src/data.c
+++ b/src/data.c
@@ -4217,10 +4217,11 @@ syms_of_data (void)
   Fput (Qrecursion_error, Qerror_message, build_pure_c_string
        ("Excessive recursive calling error"));
 
-  PUT_ERROR (Qexcessive_variable_binding, recursion_tail,
-            "Variable binding depth exceeds max-specpdl-size");
   PUT_ERROR (Qexcessive_lisp_nesting, recursion_tail,
             "Lisp nesting exceeds `max-lisp-eval-depth'");
+  /* Error obsolete (from 29.1), kept for compatibility.  */
+  PUT_ERROR (Qexcessive_variable_binding, recursion_tail,
+            "Variable binding depth exceeds max-specpdl-size");
 
   /* Types that type-of returns.  */
   DEFSYM (Qinteger, "integer");
diff --git a/src/eval.c b/src/eval.c
index 1a4d3ad0307..545a280ae91 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -2373,8 +2373,7 @@ grow_specpdl_allocation (void)
   union specbinding *pdlvec = specpdl - 1;
   ptrdiff_t size = specpdl_end - specpdl;
   ptrdiff_t pdlvecsize = size + 1;
-  if (max_size <= size)
-    xsignal0 (Qexcessive_variable_binding);  /* Can't happen, essentially.  */
+  eassert (max_size > size);
   pdlvec = xpalloc (pdlvec, &pdlvecsize, 1, max_size + 1, sizeof *specpdl);
   specpdl = pdlvec + 1;
   specpdl_end = specpdl + pdlvecsize - 1;