builtin: cleanup by turning backtrace* fns to ordinary C. fns

vlib/builtin/builtin_nix.c.v

@@ -64,8 +64,8 @@ fn print_backtrace_skipping_top_frames(xskipframes int) bool {
 fn print_backtrace_skipping_top_frames_mac(skipframes int) bool {
 	$if macos {
 		buffer := [100]byteptr
-		nr_ptrs := backtrace(buffer, 100)
+		nr_ptrs := C.backtrace(buffer, 100)
-		backtrace_symbols_fd(&buffer[skipframes], nr_ptrs - skipframes, 2)
+		C.backtrace_symbols_fd(&buffer[skipframes], nr_ptrs - skipframes, 2)
 	}
 	return true
 }
@@ -73,28 +73,35 @@ fn print_backtrace_skipping_top_frames_mac(skipframes int) bool {
 fn print_backtrace_skipping_top_frames_freebsd(skipframes int) bool {
 	$if freebsd {
 		buffer := [100]byteptr
-		nr_ptrs := backtrace(buffer, 100)
+		nr_ptrs := C.backtrace(buffer, 100)
-		backtrace_symbols_fd(&buffer[skipframes], nr_ptrs - skipframes, 2)
+		C.backtrace_symbols_fd(&buffer[skipframes], nr_ptrs - skipframes, 2)
 	}
 	return true
 }
 
 fn print_backtrace_skipping_top_frames_linux(skipframes int) bool {
-	$if tinyc {
+	$if android {
-		println('TODO: print_backtrace_skipping_top_frames_linux $skipframes with tcc fails tests with "stack smashing detected" .')
+		eprintln('On Android no backtrace is available.')
+		return false
+	}
+	$if !glibc {
+		eprintln('backtrace_symbols is missing => printing backtraces is not available.')
+		eprintln('Some libc implementations like musl simply do not provide it.')
+		return false
+	}
+	$if tinyc {
+		eprintln('TODO: print_backtrace_skipping_top_frames_linux $skipframes')
+		eprintln('with tcc fails tests with "stack smashing detected" .')
 		return false
 	}
-	$if !android {
-		// backtrace is not available on Android.
-		$if glibc {
 	buffer := [100]byteptr
-			nr_ptrs := backtrace(buffer, 100)
+	nr_ptrs := C.backtrace(buffer, 100)
 	nr_actual_frames := nr_ptrs - skipframes
 	mut sframes := []string{}
 	//////csymbols := backtrace_symbols(*voidptr(&buffer[skipframes]), nr_actual_frames)
-			csymbols := backtrace_symbols(&buffer[skipframes], nr_actual_frames)
+	csymbols := C.backtrace_symbols(&buffer[skipframes], nr_actual_frames)
 	for i in 0 .. nr_actual_frames {
-				sframes << tos2( byteptr( voidptr(csymbols[i]) ) )
+		sframes << tos2( byteptr(csymbols[i]) )
 	}
 	for sframe in sframes {
 		executable := sframe.all_before('(')
@@ -126,12 +133,5 @@ fn print_backtrace_skipping_top_frames_linux(skipframes int) bool {
 		output = output.replace(' (discriminator', ': (d.')
 		eprintln('${output:-46s} | ${addr:14s} | $beforeaddr')
 	}
-			// backtrace_symbols_fd(*voidptr(&buffer[skipframes]), nr_actual_frames, 1)
 	return true
-		} $else {
-			eprintln('backtrace_symbols_fd is missing, so printing backtraces is not available.\n')
-			eprintln('Some libc implementations like musl simply do not provide it.')
-		}
-	}
-	return false
 }

vlib/builtin/cfns.c.v

@@ -26,10 +26,10 @@ fn C.isdigit(s byteptr) bool
 fn C.popen(c byteptr, t byteptr) voidptr
 
 // <execinfo.h>
-// backtrace functions are not #included, that's why they have to be defined without C.
+fn C.backtrace(a &voidptr, size int) int
-fn backtrace(a &voidptr, b int) int
+fn C.backtrace_symbols(a &voidptr, size int)  &charptr
-fn backtrace_symbols(a &voidptr, size int)  &charptr
+fn C.backtrace_symbols_fd(a &voidptr, size int, fd int)
-fn backtrace_symbols_fd(a &voidptr, size int, fd int) void
+
 // <libproc.h>
 fn proc_pidpath(int, voidptr, int) int
 

vlib/v/gen/fn.v

@@ -22,12 +22,6 @@ fn (mut g Gen) gen_fn_decl(it ast.FnDecl) {
 	if g.attr == 'inline' {
 		g.write('inline ')
 	}
-	if it.name in ['backtrace', 'backtrace_symbols', 'backtrace_symbols_fd'] {
-		// these are actually defined as C functions in execinfo.h
-		// TODO: remove this check, *after* they are defined as C. in cfns.c.v
-		// in bootstrap phase 2
-		return
-	}
 	//
 	is_livefn := g.attr == 'live'
 	is_livemain := g.pref.is_livemain && is_livefn