https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81043
Bug ID: 81043 Summary: [concepts] partially specializing on differing constraints gives cryptic error Product: gcc Version: 8.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: hstong at ca dot ibm.com Target Milestone: --- Having more than one partial specialization with, ignoring constraints, the same arguments results in a cryptic error. ### SOURCE (<stdin>): template <typename T> concept bool C0 = sizeof(T) <= 4; template <typename T> concept bool C1 = sizeof(T) > 4; template <typename T> struct A; template <C0 T> struct A<T>; template <C1 T> struct A<T>; ### COMPILER INVOCATION: g++ -fsyntax-only -x c++ -std=gnu++1z -fconcepts - ### EXPECTED OUTPUT: (rc=0) ### ACTUAL OUTPUT: <stdin>:5:24: error: 'A<T>' does not match any declaration ### COMPILER VERSION INFO (g++ -v): Using built-in specs. COLLECT_GCC=/opt/wandbox/gcc-head/bin/g++ COLLECT_LTO_WRAPPER=/opt/wandbox/gcc-head/libexec/gcc/x86_64-pc-linux-gnu/8.0.0/lto-wrapper Target: x86_64-pc-linux-gnu Configured with: ../source/configure --prefix=/opt/wandbox/gcc-head --enable-languages=c,c++ --disable-multilib --without-ppl --without-cloog-ppl --enable-checking=release --disable-nls --enable-lto LDFLAGS=-Wl,-rpath,/opt/wandbox/gcc-head/lib,-rpath,/opt/wandbox/gcc-head/lib64,-rpath,/opt/wandbox/gcc-head/lib32 Thread model: posix gcc version 8.0.0 20170608 (experimental) (GCC)