windows: fail early with a missing windres in autotools

`windres` is not always auto-detected by autotools when building for
Windows. When this happened, the build failed with a confusing error due
to the empty `RC` command:

```
/bin/bash ../libtool --tag=RC --mode=compile  -I../include -DCURL_EMBED_MANIFEST  -i curl.rc -o curl.o
[...]
Usage: /sandbox/curl/libtool [OPTION]... [MODE-ARG]...
Try 'libtool --help' for more information.
libtool:   error: unrecognised option: '-I../include'
```

Improve this by verifying if `RC` is set, and fail with a clear error
otherwise.

Follow-up to 6de7322c03d5b4d91576a7d9fc893e03cc9d1057

Ref: https://curl.se/mail/lib-2022-10/0049.html
Reported-by: Thomas Glanzmann
Closes #9781

diff --git a/configure.ac b/configure.ac
index 937404ec31e5d32fd3d5e7e617f29cd9318156c2..be1d4d405d728410eaf61bd8e7b067a93f3b5797 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -570,7 +570,13 @@ CURL_DARWIN_CFLAGS
 CURL_DARWIN_SYSTEMCONFIGURATION
 CURL_SUPPORTS_BUILTIN_AVAILABLE
 
-AM_CONDITIONAL([OS_WINDOWS], [test "$curl_cv_native_windows" = "yes"])
+AM_CONDITIONAL([HAVE_WINDRES],
+  [test "$curl_cv_native_windows" = "yes" && test -n "${RC}"])
+
+if test "$curl_cv_native_windows" = "yes"; then
+  AM_COND_IF([HAVE_WINDRES],,
+    [AC_MSG_ERROR([windres not found in PATH. Windows builds require windres. Cannot continue.])])
+fi
 
 dnl ************************************************************
 dnl switch off particular protocols

diff --git a/lib/Makefile.am b/lib/Makefile.am
index cd1ca97a54df308e2bc8331f01fa2c2cd50e60b7..3b4f742387f506c92def2fda9bfdd5886c8d9ba6 100644 (file)
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -109,7 +109,7 @@ endif
 if USE_CPPFLAG_CURL_STATICLIB
 libcurl_la_CPPFLAGS_EXTRA += -DCURL_STATICLIB
 else
-if OS_WINDOWS
+if HAVE_WINDRES
 libcurl_la_SOURCES += $(LIB_RCFILES)
 $(LIB_RCFILES): $(top_srcdir)/include/curl/curlver.h
 endif
@@ -154,7 +154,7 @@ tidy:
 optiontable:
        perl optiontable.pl < $(top_srcdir)/include/curl/curl.h > easyoptions.c
 
-if OS_WINDOWS
+if HAVE_WINDRES
 .rc.lo:
        $(LIBTOOL) --tag=RC --mode=compile $(RC) -I$(top_srcdir)/include $(RCFLAGS) -i $< -o $@
 endif

diff --git a/src/Makefile.am b/src/Makefile.am
index 2c1886f5a838abdf274ae6a8fe3dec54bf3bc81d..d746d4676fbbc5771bb8953bf0e16715888498e2 100644 (file)
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -55,7 +55,7 @@ include Makefile.inc
 
 # CURL_FILES comes from Makefile.inc
 curl_SOURCES = $(CURL_FILES)
-if OS_WINDOWS
+if HAVE_WINDRES
 curl_SOURCES += $(CURL_RCFILES)
 $(CURL_RCFILES): tool_version.h
 endif
@@ -156,7 +156,7 @@ tidy:
 listhelp:
        (cd $(top_srcdir)/docs/cmdline-opts && ./gen.pl listhelp *.d) > tool_listhelp.c
 
-if OS_WINDOWS
+if HAVE_WINDRES
 .rc.o:
        $(RC) -I$(top_srcdir)/include -DCURL_EMBED_MANIFEST $(RCFLAGS) -i $< -o $@
 endif