config: Check for program_invocation_short_name

This lets us pick it up on musl too, since there's no __MUSL__ macro.

Link: https://wiki.musl-libc.org/faq#Q:-Why-is-there-no-%3Ccode%3E__MUSL__%3C/code%3E-macro?

8 files changed, 91 insertions, 3 deletions

diff --git a/config/cc-define.sh b/config/cc-define.sh
new file mode 100755
index 0000000..edb5c87
--- /dev/null
+++ b/config/cc-define.sh
@@ -0,0 +1,19 @@
+#!/bin/sh
+
+# Copyright © Tavian Barnes <tavianator@tavianator.com>
+# SPDX-License-Identifier: 0BSD
+
+# Output a C preprocessor definition based on whether a C source file could be
+# compiled successfully
+
+set -eu
+
+SLUG="${1#config/}"
+SLUG="${SLUG%.c}"
+MACRO="BFS_HAS_$(printf '%s' "$SLUG" | tr 'a-z-' 'A-Z_')"
+
+if config/cc.sh "$1"; then
+    printf '#define %s true\n' "$MACRO"
+else
+    printf '#define %s false\n' "$MACRO"
+fi
diff --git a/config/config.mk b/config/config.mk
index 5a6f8d2..5750b49 100644
--- a/config/config.mk
+++ b/config/config.mk
@@ -6,6 +6,10 @@
 include config/prelude.mk
 include config/exports.mk
 
+# All configuration steps
+config: ${CONFIG} ${GEN}/config.h
+.PHONY: config
+
 # Makefile fragments generated by `make config`
 MKS := \
     ${GEN}/vars.mk \
@@ -17,7 +21,7 @@ MKS := \
 ${CONFIG}: ${MKS}
 	${MSG} "[ GEN] ${TGT}"
 	@printf '# %s\n' "${TGT}" >$@
-	@printf 'include $${GEN}/%s\n' ${.ALLSRC:${GEN}/%=%} >>$@
+	@printf 'include $${GEN}/%s\n' ${MKS:${GEN}/%=%} >>$@
 	${VCAT} ${CONFIG}
 .PHONY: ${CONFIG}
 
@@ -67,3 +71,8 @@ ${GEN}/pkgs.mk: ${PKG_MKS}
 ${PKG_MKS}: ${GEN}/flags.mk
 	@+${MAKE} -sf config/pkg.mk TARGET=$@
 .PHONY: ${PKG_MKS}
+
+# Compile-time feature detection
+${GEN}/config.h: ${CONFIG}
+	@+${MAKE} -sf config/header.mk $@
+.PHONY: ${GEN}/config.h
diff --git a/config/flags.mk b/config/flags.mk
index d02cc8b..9959d10 100644
--- a/config/flags.mk
+++ b/config/flags.mk
@@ -29,6 +29,7 @@ export XLDLIBS=${LDLIBS}
 # Immutable flags
 export BFS_CPPFLAGS= \
     -Isrc \
+    -I${GEN} \
     -D__EXTENSIONS__ \
     -D_ATFILE_SOURCE \
     -D_BSD_SOURCE \
diff --git a/config/getprogname-gnu.c b/config/getprogname-gnu.c
new file mode 100644
index 0000000..6b97c5e
--- /dev/null
+++ b/config/getprogname-gnu.c
@@ -0,0 +1,9 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <errno.h>
+
+int main(void) {
+	const char *str = program_invocation_short_name;
+	return str[0];
+}
diff --git a/config/getprogname.c b/config/getprogname.c
new file mode 100644
index 0000000..83dc8e8
--- /dev/null
+++ b/config/getprogname.c
@@ -0,0 +1,9 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <stdlib.h>
+
+int main(void) {
+	const char *str = getprogname();
+	return str[0];
+}
diff --git a/config/header.mk b/config/header.mk
new file mode 100644
index 0000000..3a1271e
--- /dev/null
+++ b/config/header.mk
@@ -0,0 +1,38 @@
+# Copyright © Tavian Barnes <tavianator@tavianator.com>
+# SPDX-License-Identifier: 0BSD
+
+# Makefile that generates gen/config.h
+
+include config/prelude.mk
+include ${GEN}/config.mk
+include config/exports.mk
+
+# All header fragments we generate
+HEADERS := \
+    ${GEN}/getprogname.h \
+    ${GEN}/getprogname-gnu.h
+
+${GEN}/config.h: ${HEADERS}
+	${MSG} "[ GEN] ${TGT}"
+	printf '// %s\n' "${TGT}" >$@
+	printf '#ifndef BFS_CONFIG_H\n' >>$@
+	printf '#define BFS_CONFIG_H\n' >>$@
+	cat ${.ALLSRC} >>$@
+	printf '#endif // BFS_CONFIG_H\n' >>$@
+	cat ${.ALLSRC:%=%.log} >$@.log
+	${RM} ${.ALLSRC} ${.ALLSRC:%=%.log}
+	${VCAT} $@
+.PHONY: ${GEN}/config.h
+
+# The C source file to attempt to compile
+CSRC = ${@:${GEN}/%.h=config/%.c}
+
+${HEADERS}::
+	config/cc-define.sh ${CSRC} >$@ 2>$@.log
+	if ! [ "${IS_V}" ]; then \
+	    if grep -q 'true$$' $@; then \
+	        printf '[ CC ] %-${MSG_WIDTH}s  ✔\n' ${CSRC}; \
+	    else \
+	        printf '[ CC ] %-${MSG_WIDTH}s  ✘\n' ${CSRC}; \
+	    fi; \
+	fi
diff --git a/config/pkg.mk b/config/pkg.mk
index 6f868be..fafe562 100644
--- a/config/pkg.mk
+++ b/config/pkg.mk
@@ -17,7 +17,7 @@ default::
 	@if [ "${IS_V}" ]; then \
 	    cat ${TARGET}; \
 	elif grep -q PKGS ${TARGET}; then \
-	    printf '[ GEN] %-18s  ✔\n' ${SHORT}; \
+	    printf '[ GEN] %-${MSG_WIDTH}s  ✔\n' ${SHORT}; \
 	else \
-	    printf '[ GEN] %-18s  ✘\n' ${SHORT}; \
+	    printf '[ GEN] %-${MSG_WIDTH}s  ✘\n' ${SHORT}; \
 	fi
diff --git a/config/prelude.mk b/config/prelude.mk
index dbc6875..0ac5fde 100644
--- a/config/prelude.mk
+++ b/config/prelude.mk
@@ -109,6 +109,9 @@ MSG = @msg() { \
       }; \
       msg
 
+# Maximum width of a short message, to align the [X]
+MSG_WIDTH := 24
+
 # cat a file if V=1
 VCAT,y := @cat
 VCAT,  := @: