https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105418
--- Comment #5 from Jiu Fu Guo <guojiufu at gcc dot gnu.org> --- 0x1089f887 dump_substitution /home/guojiufu/gcc/gcc-mainline-base/gcc/cp/error.cc:1654 0x108a1c2f dump_function_decl /home/guojiufu/gcc/gcc-mainline-base/gcc/cp/error.cc:1817 0x1089e187 dump_decl /home/guojiufu/gcc/gcc-mainline-base/gcc/cp/error.cc:1385 0x108aa8df decl_as_string(tree_node*, int) /home/guojiufu/gcc/gcc-mainline-base/gcc/cp/error.cc:3146 0x1094d6ef trees_out::insert(tree_node*, walk_kind) /home/guojiufu/gcc/gcc-mainline-base/gcc/cp/module.cc:4801 0x1096300f trees_out::decl_node(tree_node*, walk_kind) /home/guojiufu/gcc/gcc-mainline-base/gcc/cp/module.cc:8582 0x10965da3 trees_out::tree_node(tree_node*) /home/guojiufu/gcc/gcc-mainline-base/gcc/cp/module.cc:9104 0x109542c7 trees_out::core_vals(tree_node*) /home/guojiufu/gcc/gcc-mainline-base/gcc/cp/module.cc:5924 0x10959d4f trees_out::tree_node_vals(tree_node*) /home/guojiufu/gcc/gcc-mainline-base/gcc/cp/module.cc:7074 0x10964dab trees_out::tree_value(tree_node*) /home/guojiufu/gcc/gcc-mainline-base/gcc/cp/module.cc:8911 0x10965ddf trees_out::tree_node(tree_node*) /home/guojiufu/gcc/gcc-mainline-base/gcc/cp/module.cc:9109 0x109542c7 trees_out::core_vals(tree_node*) /home/guojiufu/gcc/gcc-mainline-base/gcc/cp/module.cc:5924 0x10959d4f trees_out::tree_node_vals(tree_node*) /home/guojiufu/gcc/gcc-mainline-base/gcc/cp/module.cc:7074 Please submit a full bug report, with preprocessed source (by using -freport-bug). Please include the complete backtrace with any bug report. See <https://gcc.gnu.org/bugs/> for instructions. Hi Andrew and Richard, Thanks a lot! This issue happens when calling debug_tree/decl_as_string manually inside FE. At where overloaded functions (::new) are not resolved yet, and then cause 'tsubst' to be called. I see, it is not a good place to use debug_tree.