configure: Use a separate config_components.h header for $ALL_COMPONENTS

This avoids unnecessary rebuilds of most source files if only the
list of enabled components has changed, but not the other properties
of the build, set in config.h.

Signed-off-by: Martin Storsjö <martin@martin.st>

1 files changed, 15 insertions, 2 deletions

diff --git a/configure b/configure
index 82642deabe..dff53e88bc 100755
--- a/configure
+++ b/configure
@@ -7791,17 +7791,30 @@ print_config ARCH_   "$config_files" $ARCH_LIST
 print_config HAVE_   "$config_files" $HAVE_LIST
 print_config CONFIG_ "$config_files" $CONFIG_LIST       \
                                      $CONFIG_EXTRA      \
-                                     $ALL_COMPONENTS    \
 
 echo "#endif /* FFMPEG_CONFIG_H */" >> $TMPH
-echo "endif # FFMPEG_CONFIG_MAK" >> ffbuild/config.mak
 
 # Do not overwrite an unchanged config.h to avoid superfluous rebuilds.
 cp_if_changed $TMPH config.h
 touch ffbuild/.config
 
+# Copy config.asm before printing ALL_COMPONENTS; that's not needed in assembly.
 enabled x86asm && cp_if_changed $TMPASM config.asm
 
+# Reopen a new TMPH for config_components.h.
+cat > $TMPH <<EOF
+/* Automatically generated by configure - do not modify! */
+#ifndef FFMPEG_CONFIG_COMPONENTS_H
+#define FFMPEG_CONFIG_COMPONENTS_H
+EOF
+
+print_config CONFIG_ "$config_files" $ALL_COMPONENTS
+
+echo "#endif /* FFMPEG_CONFIG_COMPONENTS_H */" >> $TMPH
+echo "endif # FFMPEG_CONFIG_MAK" >> ffbuild/config.mak
+
+cp_if_changed $TMPH config_components.h
+
 cat > $TMPH <<EOF
 /* Generated by ffmpeg configure */
 #ifndef AVUTIL_AVCONFIG_H