From: Serhiy Storchaka <storchaka@gmail.com>
Date: Sat, 11 Jul 2026 09:49:12 +0000 (+0300)
Subject: gh-126877: Fix the configure check for Tcl/Tk with optimizing compilers (GH-153543)
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ff0a9ae269fa38c21f01bdea1a7ff5d439c4f681;p=thirdparty%2FPython%2Fcpython.git

gh-126877: Fix the configure check for Tcl/Tk with optimizing compilers (GH-153543)

The check assigned the addresses of Tcl_Init() and Tk_Init() to unused
variables, which optimizing compilers can eliminate, so it linked even
when the libraries were missing.  Call the functions instead.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
---

diff --git a/Misc/NEWS.d/next/Build/2026-07-11-07-26-16.gh-issue-126877.Zt7Kq2.rst b/Misc/NEWS.d/next/Build/2026-07-11-07-26-16.gh-issue-126877.Zt7Kq2.rst
new file mode 100644
index 000000000000..1d7d4fad886c
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2026-07-11-07-26-16.gh-issue-126877.Zt7Kq2.rst
@@ -0,0 +1,2 @@
+Fix the :program:`configure` check for Tcl/Tk which could wrongly succeed
+with optimizing compilers when the libraries are missing.
diff --git a/configure b/configure
index 17b7ef765cc7..c15bc2867b94 100755
--- a/configure
+++ b/configure
@@ -17975,8 +17975,8 @@ int
 main (void)
 {
 
-      void *x1 = Tcl_Init;
-      void *x2 = Tk_Init;
+      Tcl_Init(NULL);
+      Tk_Init(NULL);
 
   ;
   return 0;
diff --git a/configure.ac b/configure.ac
index ab64ac8769b5..2726a835efc5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -4618,8 +4618,8 @@ WITH_SAVE_ENV([
       #  error "Tk older than 8.5.12 not supported"
       #endif
     ], [
-      void *x1 = Tcl_Init;
-      void *x2 = Tk_Init;
+      Tcl_Init(NULL);
+      Tk_Init(NULL);
     ])
   ], [
     have_tcltk=yes