https://github.com/libsdl-org/autoconf/commit/dc28f7c20b2f4079ddb259432a17bd8a584343a9
From dc28f7c20b2f4079ddb259432a17bd8a584343a9 Mon Sep 17 00:00:00 2001
From: Paul Eggert <[EMAIL REDACTED]>
Date: Tue, 10 May 2022 14:23:06 -0700
Subject: [PATCH] Document AC_RUN_IFELSE([], ...) etc.
* doc/autoconf.texi (Running the Preprocessor)
(Running the Compiler, Running the Linker, Runtime):
Document that the _IFELSE macros reuse an existing input file
if their input is empty.
---
doc/autoconf.texi | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index f5caa71d..245fbe87 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -9642,6 +9642,9 @@ Run the preprocessor of the current language (@pxref{Language Choice})
on the @var{input}, run the shell commands @var{action-if-true} on
success, @var{action-if-false} otherwise.
+If @var{input} is nonempty use the equivalent of
+@code{AC_LANG_CONFTEST(@var{input})} to generate the current test source
+file; otherwise reuse the already-existing test source file.
The @var{input} can be made by @code{AC_LANG_PROGRAM} and friends.
The @var{input} text is expanded as an unquoted here-document, so
@samp{$}, @samp{`} and some @samp{\}s should be backslash-escaped.
@@ -9763,6 +9766,9 @@ Run the compiler and compilation flags of the current language
(@pxref{Language Choice}) on the @var{input}, run the shell commands
@var{action-if-true} on success, @var{action-if-false} otherwise.
+If @var{input} is nonempty use the equivalent of
+@code{AC_LANG_CONFTEST(@var{input})} to generate the current test source
+file; otherwise reuse the already-existing test source file.
The @var{input} can be made by @code{AC_LANG_PROGRAM} and friends.
The @var{input} text is expanded as an unquoted here-document, so
@samp{$}, @samp{`} and some @samp{\}s should be backslash-escaped.
@@ -9819,6 +9825,9 @@ commands @var{action-if-true} on success, @var{action-if-false}
otherwise. If needed, @var{action-if-true} can further access the
just-linked program file @file{conftest$EXEEXT}.
+If @var{input} is nonempty use the equivalent of
+@code{AC_LANG_CONFTEST(@var{input})} to generate the current test source
+file; otherwise reuse the already-existing test source file.
The @var{input} can be made by @code{AC_LANG_PROGRAM} and friends.
The @var{input} text is expanded as an unquoted here-document, so
@samp{$}, @samp{`} and some @samp{\}s should be backslash-escaped.
@@ -9862,6 +9871,9 @@ resulting program. If the program returns an exit
status of 0 when executed, run shell commands @var{action-if-true}.
Otherwise, run shell commands @var{action-if-false}.
+If @var{input} is nonempty use the equivalent of
+@code{AC_LANG_CONFTEST(@var{input})} to generate the current test source
+file; otherwise reuse the already-existing test source file.
The @var{input} can be made by @code{AC_LANG_PROGRAM} and friends.
The @var{input} text is expanded as an unquoted here-document, so
@samp{$}, @samp{`} and some @samp{\}s should be backslash-escaped.