From 6398043094e8eeec1727e7e23b5ca595a61f04e8 Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Mon, 6 Jun 2022 14:33:24 +0300
Subject: [PATCH] cgen: fix missing function names in declarations on
 `[c2v_variadic][c: xyz]fn deh_fprintf(fstream &C.FILE, fmt &i8)`

---
 vlib/v/ast/attr.v   | 19 +++++++++++++++++++
 vlib/v/gen/c/cgen.v | 18 +++++++++---------
 vlib/v/gen/c/fn.v   | 28 ++++++++++++----------------
 3 files changed, 40 insertions(+), 25 deletions(-)

diff --git a/vlib/v/ast/attr.v b/vlib/v/ast/attr.v
index 973d542bd0..0366129f0f 100644
--- a/vlib/v/ast/attr.v
+++ b/vlib/v/ast/attr.v
@@ -54,6 +54,25 @@ pub fn (attrs []Attr) contains(str string) bool {
 	return attrs.any(it.name == str)
 }
 
+pub fn (attrs []Attr) find_first(aname string) ?Attr {
+	for a in attrs {
+		if a.name == aname {
+			return a
+		}
+	}
+	return none
+}
+
+pub fn (attrs []Attr) find_last(aname string) ?Attr {
+	for idx := attrs.len - 1; idx > -1; idx-- {
+		a := attrs[idx]
+		if a.name == aname {
+			return a
+		}
+	}
+	return none
+}
+
 pub fn (attrs []Attr) find_comptime_define() ?int {
 	for idx in 0 .. attrs.len {
 		if attrs[idx].kind == .comptime_define {
diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index b26ad28a6e..fcf03d3138 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -3925,8 +3925,8 @@ fn (mut g Gen) ident(node ast.Ident) {
 			// `p_mobjthinker` => `P_MobjThinker`
 			if f := g.table.find_fn(node.name) {
 				// TODO PERF fn lookup for each fn call in translated mode
-				if f.attrs.contains('c') {
-					name = f.attrs[0].arg
+				if cattr := f.attrs.find_first('c') {
+					name = cattr.arg
 				}
 			}
 		}
@@ -3970,8 +3970,8 @@ fn (mut g Gen) cast_expr(node ast.CastExpr) {
 			// TODO handle the type in fn casts, not just exprs
 			/*
 			info := sym.info as ast.FnType
-			if info.func.attrs.contains('c') {
-				// name = f.attrs[0].arg
+			if cattr := info.func.attrs.find_first('c') {
+				name = cattr.arg
 			}
 			*/
 		}
@@ -4398,11 +4398,11 @@ fn (mut g Gen) const_decl(node ast.ConstDecl) {
 			}
 		}
 		name := c_name(field.name)
-		const_name := if node.attrs.contains('export') && !g.is_builtin_mod {
-			// TODO this only works for the first const in the group for now
-			node.attrs[0].arg
-		} else {
-			'_const_' + name
+		mut const_name := '_const_' + name
+		if !g.is_builtin_mod {
+			if cattr := node.attrs.find_first('export') {
+				const_name = cattr.arg
+			}
 		}
 		field_expr := field.expr
 		match field.expr {
diff --git a/vlib/v/gen/c/fn.v b/vlib/v/gen/c/fn.v
index 50525aea96..ee9fc70e4e 100644
--- a/vlib/v/gen/c/fn.v
+++ b/vlib/v/gen/c/fn.v
@@ -446,20 +446,16 @@ fn (mut g Gen) c_fn_name(node &ast.FnDecl) ?string {
 		name = g.generic_fn_name(g.cur_concrete_types, name, true)
 	}
 
-	if (g.pref.translated || g.file.is_translated) && node.attrs.contains('c') {
-		// This fixes unknown symbols errors when building separate .c => .v files
-		// into .o files
-		//
-		// example:
-		// [c: 'P_TryMove']
-		// fn p_trymove(thing &Mobj_t, x int, y int) bool
-		//
-		// =>
-		//
-		// bool P_TryMove(main__Mobj_t* thing, int x, int y);
-		//
-		// In fn_call every time `p_trymove` is called, `P_TryMove` will be generated instead.
-		name = node.attrs[0].arg
+	if g.pref.translated || g.file.is_translated {
+		if cattr := node.attrs.find_first('c') {
+			// This fixes unknown symbols errors when building separate .c => .v files into .o files
+			// example:
+			// [c: 'P_TryMove'] fn p_trymove(thing &Mobj_t, x int, y int) bool
+			// translates to:
+			// bool P_TryMove(main__Mobj_t* thing, int x, int y);
+			// In fn_call every time `p_trymove` is called, `P_TryMove` will be generated instead.
+			name = cattr.arg
+		}
 	}
 	return name
 }
@@ -1239,8 +1235,8 @@ fn (mut g Gen) fn_call(node ast.CallExpr) {
 		// every time `p_trymove` is called, `P_TryMove` must be generated instead.
 		if f := g.table.find_fn(node.name) {
 			// TODO PERF fn lookup for each fn call in translated mode
-			if f.attrs.contains('c') {
-				name = f.attrs[0].arg
+			if cattr := f.attrs.find_first('c') {
+				name = cattr.arg
 			}
 		}
 	}