cgen: fix compilation for a project using a lot of json, threads, embeds + parallel-cc (#23467)

vlib/v/gen/c/cgen.v

@@ -600,9 +600,6 @@ pub fn gen(files []&ast.File, mut table ast.Table, pref_ &pref.Preferences) GenO
 	if g.out_results.len > 0 {
 		b.write_string2('\n// V result_xxx definitions:\n', g.out_results.str())
 	}
-	if g.json_forward_decls.len > 0 {
-		b.write_string2('\n// V json forward decls:\n', g.json_forward_decls.str())
-	}
 	b.write_string2('\n// V definitions:\n', g.definitions.str())
 	if g.sort_fn_definitions.len > 0 {
 		b.write_string2('\n// V sort fn definitions:\n', g.sort_fn_definitions.str())
@@ -621,18 +618,9 @@ pub fn gen(files []&ast.File, mut table ast.Table, pref_ &pref.Preferences) GenO
 	if interface_table.len > 0 {
 		b.write_string2('\n// V interface table:\n', interface_table)
 	}
-	if g.waiter_fn_definitions.len > 0 {
-		b.write_string2('\n// V gowrappers waiter fns:\n', g.waiter_fn_definitions.str())
-	}
-	if g.gowrappers.len > 0 {
-		b.write_string2('\n// V gowrappers:\n', g.gowrappers.str())
-	}
 	if g.hotcode_definitions.len > 0 {
 		b.write_string2('\n// V hotcode definitions:\n', g.hotcode_definitions.str())
 	}
-	if g.embedded_data.len > 0 {
-		b.write_string2('\n// V embedded data:\n', g.embedded_data.str())
-	}
 	if g.shared_functions.len > 0 {
 		b.writeln('\n// V shared type functions:\n')
 		b.write_string2(g.shared_functions.str(), c_concurrency_helpers)
@@ -659,10 +647,13 @@ pub fn gen(files []&ast.File, mut table ast.Table, pref_ &pref.Preferences) GenO
 	header = '#ifndef V_HEADER_FILE\n#define V_HEADER_FILE' + header
 	header += '\n#endif\n'
 
-	mut helpers := strings.new_builder(200_000)
+	mut helpers := strings.new_builder(300_000)
 	// Code added here (after the header) goes to out_0.c in parallel cc mode
 	// Previously it went to the header which resulted in duplicated code and more code
 	// to compile for the C compiler
+	if g.embedded_data.len > 0 {
+		helpers.write_string2('\n// V embedded data:\n', g.embedded_data.str())
+	}
 	if g.anon_fn_definitions.len > 0 {
 		if g.nr_closures > 0 {
 			helpers.writeln2('\n// V closure helpers', c_closure_fn_helpers(g.pref))
@@ -693,6 +684,12 @@ pub fn gen(files []&ast.File, mut table ast.Table, pref_ &pref.Preferences) GenO
 			}
 		}
 	}
+	if g.waiter_fn_definitions.len > 0 {
+		if g.pref.parallel_cc {
+			g.extern_out.write_string2('\n// V gowrappers waiter fns:\n', g.waiter_fn_definitions.bytestr())
+		}
+		helpers.write_string2('\n// V gowrappers waiter fns:\n', g.waiter_fn_definitions.str())
+	}
 	if g.auto_str_funcs.len > 0 {
 		helpers.write_string2('\n// V auto str functions:\n', g.auto_str_funcs.str())
 	}
@@ -702,6 +699,15 @@ pub fn gen(files []&ast.File, mut table ast.Table, pref_ &pref.Preferences) GenO
 			helpers.writeln(fn_def)
 		}
 	}
+	if g.json_forward_decls.len > 0 {
+		helpers.write_string2('\n// V json forward decls:\n', g.json_forward_decls.bytestr())
+		if g.pref.parallel_cc {
+			g.extern_out.write_string2('\n// V json forward decls:\n', g.json_forward_decls.str())
+		}
+	}
+	if g.gowrappers.len > 0 {
+		helpers.write_string2('\n// V gowrappers:\n', g.gowrappers.str())
+	}
 	if g.dump_funcs.len > 0 {
 		helpers.write_string2('\n// V dump functions:\n', g.dump_funcs.str())
 	}
@@ -1152,6 +1158,9 @@ pub fn (mut g Gen) write_typeof_functions() {
 			}
 			g.writeln2('\treturn "unknown ${util.strip_main_name(sym.name)}";', '}')
 			g.writeln2('', 'int v_typeof_interface_idx_${sym.cname}(int sidx) {')
+			if g.pref.parallel_cc {
+				g.extern_out.writeln('extern int v_typeof_interface_idx_${sym.cname}(int sidx);')
+			}
 			for t in inter_info.types {
 				sub_sym := g.table.sym(ast.mktyp(t))
 				if sub_sym.info is ast.Struct && sub_sym.info.is_unresolved_generic() {

vlib/v/gen/c/embed.v

@@ -85,6 +85,9 @@ fn (mut g Gen) gen_embed_file_init(mut node ast.ComptimeCall) {
 // into a single generated function _v_embed_file_metadata, that accepts a hash of the absolute path of the embedded
 // files.
 fn (mut g Gen) gen_embedded_metadata() {
+	if g.pref.parallel_cc {
+		g.extern_out.writeln('extern v__embed_file__EmbedFileData _v_embed_file_metadata(u64 ef_hash);')
+	}
 	g.embedded_data.writeln('v__embed_file__EmbedFileData _v_embed_file_metadata(u64 ef_hash) {')
 	g.embedded_data.writeln('\tv__embed_file__EmbedFileData res;')
 	g.embedded_data.writeln('\tmemset(&res, 0, sizeof(res));')

vlib/v/gen/c/json.v

@@ -119,12 +119,13 @@ ${dec_fn_dec} {
 		}
 	}
 ')
-		g.json_forward_decls.writeln('${dec_fn_dec};')
+		extern_str := if g.pref.parallel_cc { 'extern ' } else { '' }
+		g.json_forward_decls.writeln('${extern_str}${dec_fn_dec};')
 		// Codegen encoder
 		// encode_TYPE funcs receive an object to encode
 		enc_fn_name := js_enc_name(styp)
 		enc_fn_dec := 'cJSON* ${enc_fn_name}(${styp} val)'
-		g.json_forward_decls.writeln('${enc_fn_dec};\n')
+		g.json_forward_decls.writeln('${extern_str}${enc_fn_dec};\n')
 		enc.writeln('
 ${enc_fn_dec} {
 \tcJSON *o;')

vlib/v/gen/c/spawn_and_go.v

@@ -305,7 +305,7 @@ fn (mut g Gen) spawn_and_go_expr(node ast.SpawnExpr, mode SpawnGoMode) {
 		}
 		g.type_definitions.writeln('} ${wrapper_struct_name};')
 		thread_ret_type := if g.pref.os == .windows { 'u32' } else { 'void*' }
-		g.type_definitions.writeln('${g.static_modifier} ${thread_ret_type} ${wrapper_fn_name}(${wrapper_struct_name} *arg);')
+		g.waiter_fn_definitions.writeln('${g.static_non_parallel}${thread_ret_type} ${wrapper_fn_name}(${wrapper_struct_name} *arg);')
 		g.gowrappers.writeln('${thread_ret_type} ${wrapper_fn_name}(${wrapper_struct_name} *arg) {')
 		if call_ret_type != ast.void_type {
 			if g.pref.os == .windows {