build/flags-if: Support multiple flag groups

3 files changed, 65 insertions, 31 deletions

diff --git a/build/cc.sh b/build/cc.sh
index e1d2b0b..b6f38b5 100755
--- a/build/cc.sh
+++ b/build/cc.sh
@@ -9,26 +9,11 @@
 
 set -eu
 
-QUIET=
+# Without -q, print the executed command for config.log
 if [ "$1" = "-q" ]; then
-    QUIET=y
     shift
-fi
-
-# Source files can specify their own flags with lines like
-#
-#     /// _CFLAGS += -Wmissing-variable-declarations
-#
-# which will be added to the makefile on success, or lines like
-#
-#     /// -Werror
-#
-# which are just used for the current file.
-EXTRA_FLAGS=$(sed -n '\|^///|{s|^/// ||; s|[^=]*= ||; p;}' "$1")
-
-# Without -q, print the executed command for config.log
-if [ -z "$QUIET" ]; then
+else
     set -x
 fi
 
-$XCC $XCPPFLAGS $XCFLAGS $XLDFLAGS "$@" $EXTRA_FLAGS $XLDLIBS
+$XCC $XCPPFLAGS $XCFLAGS $XLDFLAGS "$@" $XLDLIBS
diff --git a/build/flags-if.sh b/build/flags-if.sh
index 81eb345..4cbfbc9 100755
--- a/build/flags-if.sh
+++ b/build/flags-if.sh
@@ -3,26 +3,75 @@
 # Copyright © Tavian Barnes <tavianator@tavianator.com>
 # SPDX-License-Identifier: 0BSD
 
-# Add flags to a makefile if a build succeeds
+# Add flags to a makefile if a build succeeds.  Source files can specify their
+# own flags with lines like
+#
+#     /// _CFLAGS += -Wmissing-variable-declarations
+#
+# which will be added to the makefile on success, or lines like
+#
+#     /// -Werror
+#
+# which are just used for the current file.  Lines like
+#
+#     /// ---
+#
+# separate groups of flags, to try multiple ways to achieve something, e.g.
+#
+#     /// CFLAGS += -pthread
+#     /// ---
+#     /// LDLIBS += -lpthread
 
 set -eu
 
-build/cc.sh "$@" || exit 1
+# Any new flags we're using
+FLAGS=""
+# Any new makefile lines we're printing
+OUTPUT=""
 
-# If the build succeeded, print any lines like
-#
-#     /// _CFLAGS += -foo
-#
-# (unless they're already set)
-OLD_FLAGS="$XCC $XCPPFLAGS $XCFLAGS $XLDFLAGS $XLDLIBS"
+# Check the existing flags so we don't add duplicates
+OLD_FLAGS=" $XCPPFLAGS $XCFLAGS $XLDFLAGS $XLDLIBS "
+
+add_flag() {
+    if [ "${OLD_FLAGS#* $1 }" = "$OLD_FLAGS" ]; then
+        FLAGS="${FLAGS}${FLAGS:+ }$1"
+    else
+        return 1
+    fi
+}
+
+try_cc() {
+    build/cc.sh "$@" $FLAGS || return $?
+    printf '%s' "$OUTPUT"
+    exit
+}
 
 while IFS="" read -r line; do
     case "$line" in
-        ///*=*)
-            flag="${line#*= }"
-            if [ "${OLD_FLAGS#*"$flag"}" = "$OLD_FLAGS" ]; then
-                printf '%s\n' "${line#/// }"
+        "/// "*)
+            line="${line#/// }"
+            ;;
+        *)
+            continue
+            ;;
+    esac
+
+    case "$line" in
+        ---)
+            try_cc "$@" || :
+            FLAGS=
+            OUTPUT=
+            ;;
+        *=*)
+            if add_flag "${line#*= }"; then
+                OUTPUT="${OUTPUT}${line}
+"
             fi
             ;;
+        *)
+            add_flag "$line" || :
+            ;;
     esac
 done <"$1"
+
+try_cc "$@"
diff --git a/build/header.mk b/build/header.mk
index f15829a..723922e 100644
--- a/build/header.mk
+++ b/build/header.mk
@@ -89,5 +89,5 @@ OUT = ${SLUG:has/%=gen/has/.%.out}
 
 ${HEADERS}::
 	@${MKDIR} ${@D}
-	@build/define-if.sh ${SLUG} build/cc.sh build/${SLUG}.c -o ${OUT} >$@ 2>$@.log; \
+	@build/define-if.sh ${SLUG} build/flags-if.sh build/${SLUG}.c -o ${OUT} >$@ 2>$@.log; \
 	    build/msg-if.sh "[ CC ] ${SLUG}.c" test $$? -eq 0