cmd/cgo: Wrong types in compiler errors with clang 14

[dmgk]

When compiling this code on FreeBSD 14-CURRENT with clang 14, go emits error messages with invalid types:

package main

import "C"

func main() {
        var _ C.ulong = "ul"
        var _ C.ulonglong = "ull"
}

$ go build example.go
# command-line-arguments
./example.go:6:18: cannot use "ul" (untyped string constant) as _Ctype_unsignedlong value in variable declaration
./example.go:7:22: cannot use "ull" (untyped string constant) as _Ctype_unsignedlonglong value in variable declaration

cgo tests also currently are failing:

##### Test execution environment.
# GOARCH: amd64
# CPU: Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz
# GOOS: freebsd
# OS Version: FreeBSD 14.0-CURRENT FreeBSD 14.0-CURRENT #0 main-n255691-41ce5498f8e: Wed May 18 10:46:22 -05 2022     root@xombo.locald
omain:/usr/obj/usr/src/amd64.amd64/sys/XOMBO  amd64
...
##### ../misc/cgo/errors
--- FAIL: TestReportsTypeErrors (0.38s)
    --- FAIL: TestReportsTypeErrors/err2.go (0.32s)
        errors_test.go:76: found match for `err2\.go:37:`: "testdata/err2.go:37:11: cannot use s (variable of type string) as type C.unsignedlong in argument to (C._CMalloc)"
        errors_test.go:76: found match for `err2\.go:40:`: "testdata/err2.go:40:11: cannot use x (variable of type *C.struct_bar) as type *C.struct_foo in assignment"
        errors_test.go:76: found match for `:44:.*C\.ushort`: "testdata/err2.go:44:7: cannot use int(0) (constant 0 of type int) as type C.ushort in assignment"
        errors_test.go:76: found match for `err2\.go:47:`: "testdata/err2.go:47:6: not enough arguments in call to (C.fopen)"
        errors_test.go:76: found match for `:51:.*C\.int`: "testdata/err2.go:51:27: cannot use x2 (variable of type rune) as type C.int in argument to (C.transform)"
        errors_test.go:76: found match for `:56:.*C\.uchar`: "testdata/err2.go:56:23: cannot use \"uc\" (untyped string constant) as C.uchar value in variable declaration"
        errors_test.go:76: found match for `:57:.*C\.schar`: "testdata/err2.go:57:23: cannot use \"sc\" (untyped string constant) as C.schar value in variable declaration"
        errors_test.go:76: found match for `:58:.*C\.ushort`: "testdata/err2.go:58:23: cannot use \"us\" (untyped string constant) as C.ushort value in variable declaration"
        errors_test.go:76: found match for `:59:.*C\.uint`: "testdata/err2.go:59:23: cannot use \"ui\" (untyped string constant) as C.uint value in variable declaration"
        errors_test.go:82: expected error output to contain `:60:.*C\.ulong`
        errors_test.go:76: found match for `:61:.*C\.longlong`: "testdata/err2.go:61:23: cannot use \"ll\" (untyped string constant) as C.longlong value in variable declaration"
        errors_test.go:82: expected error output to contain `:62:.*C\.ulonglong`
        errors_test.go:76: found match for `:63:.*C\.complexfloat`: "testdata/err2.go:63:23: cannot use \"cf\" (untyped string constant) as C.complexfloat value in variable declaration"
        errors_test.go:76: found match for `:64:.*C\.complexdouble`: "testdata/err2.go:64:23: cannot use \"cd\" (untyped string constant) as C.complexdouble value in variable declaration"
        errors_test.go:76: found match for `err2\.go:75:`: "testdata/err2.go:75:44: cannot use _cgo0 (variable of type **C.void) as type *unsafe.Pointer in argument to C.F"
        errors_test.go:76: found match for `err2\.go:82:`: "testdata/err2.go:82:12: not enough arguments in call to (C.fvi)"
        errors_test.go:76: found match for `err2\.go:89:`: "testdata/err2.go:89:24: cannot use _cgo0 (variable of type *x) as type **C.int in argument to C.fppi"
        errors_test.go:76: found match for `:98:.*\b(10|14)\b`: "testdata/err2.go:98:10: cannot use (*C.i) + 1 (value of type C.int) as type int in return statement"
        errors_test.go:76: found match for `:105:.*\b(7|8)\b`: "testdata/err2.go:105:8: cannot use i (variable of type int) as type C.int in argument to (C.fi)"
        errors_test.go:76: found match for `err2\.go:108:`: "testdata/err2.go:108:2: cannot assign to (_Cgo_ptr(_Cfpvar_fp_fi)) (value of type unsafe.Pointer)"
        errors_test.go:87: actual output:
            # command-line-arguments
            testdata/err2.go:37:11: cannot use s (variable of type string) as type C.unsignedlong in argument to (C._CMalloc)
            testdata/err2.go:40:11: cannot use x (variable of type *C.struct_bar) as type *C.struct_foo in assignment
            testdata/err2.go:44:7: cannot use int(0) (constant 0 of type int) as type C.ushort in assignment
            testdata/err2.go:47:6: not enough arguments in call to (C.fopen)
                have ()
                want (*C.char, *C.char)
            testdata/err2.go:51:27: cannot use x2 (variable of type rune) as type C.int in argument to (C.transform)
            testdata/err2.go:51:15: cannot use (C.transform)(x2) (value of type C.int) as type rune in variable declaration
            testdata/err2.go:56:23: cannot use "uc" (untyped string constant) as C.uchar value in variable declaration
            testdata/err2.go:57:23: cannot use "sc" (untyped string constant) as C.schar value in variable declaration
            testdata/err2.go:58:23: cannot use "us" (untyped string constant) as C.ushort value in variable declaration
            testdata/err2.go:59:23: cannot use "ui" (untyped string constant) as C.uint value in variable declaration
            testdata/err2.go:60:23: cannot use "ul" (untyped string constant) as C.unsignedlong value in variable declaration
            testdata/err2.go:61:23: cannot use "ll" (untyped string constant) as C.longlong value in variable declaration
            testdata/err2.go:62:23: cannot use "ull" (untyped string constant) as C.unsignedlonglong value in variable declaration
            testdata/err2.go:63:23: cannot use "cf" (untyped string constant) as C.complexfloat value in variable declaration
            testdata/err2.go:64:23: cannot use "cd" (untyped string constant) as C.complexdouble value in variable declaration
            testdata/err2.go:75:44: cannot use _cgo0 (variable of type **C.void) as type *unsafe.Pointer in argument to C.F
            testdata/err2.go:82:12: not enough arguments in call to (C.fvi)
                have (number)
                want (unsafe.Pointer, C.int)
            testdata/err2.go:89:24: cannot use _cgo0 (variable of type *x) as type **C.int in argument to C.fppi
            testdata/err2.go:98:10: cannot use (*C.i) + 1 (value of type C.int) as type int in return statement
            testdata/err2.go:105:8: cannot use i (variable of type int) as type C.int in argument to (C.fi)
            testdata/err2.go:108:2: cannot assign to (_Cgo_ptr(_Cfpvar_fp_fi)) (value of type unsafe.Pointer)
FAIL

The above was tested with

$ go version
go version devel go1.19-d8762b2f45 Thu May 19 21:33:15 2022 +0000 freebsd/amd64

$ clang --version
FreeBSD clang version 14.0.3 (https://github.com/llvm/llvm-project.git llvmorg-14.0.3-0-g1f9140064dfb)
Target: x86_64-unknown-freebsd14.0
Thread model: posix
InstalledDir: /usr/bin

This issue seems to be similar to #13129 and #13635, CL incoming shortly.

[gopherbot]

Change https://go.dev/cl/407514 mentions this issue: cmd/cgo: handle Clang 14 DWARF quirks

[mknyszek]

CC @golang/runtime, maybe @thanm?