diff options
| author | Robert Griesemer <gri@golang.org> | 2021-11-02 09:58:12 -0700 |
|---|---|---|
| committer | Robert Griesemer <gri@golang.org> | 2021-11-03 00:21:24 +0000 |
| commit | 8f0ca7dc720b7197c91e02c8cef6e19ad95978d0 (patch) | |
| tree | e393b344744d09fbc872f3c9749749c607ff90eb /src | |
| parent | 49a00631b118834010e4d0124ccc04eeaf2cd7ac (diff) | |
| download | go-8f0ca7dc720b7197c91e02c8cef6e19ad95978d0.tar.xz | |
cmd/compile/internal/types2: report cause for failing const conversions
Follow-up on CL 360396.
Change-Id: Icd802baffb1fef91f8fef0070b6167a438ceda1a
Reviewed-on: https://go-review.googlesource.com/c/go/+/360795
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
Diffstat (limited to 'src')
| -rw-r--r-- | src/cmd/compile/internal/types2/conversions.go | 11 | ||||
| -rw-r--r-- | src/cmd/compile/internal/types2/testdata/spec/conversions.go2 | 13 |
2 files changed, 22 insertions, 2 deletions
diff --git a/src/cmd/compile/internal/types2/conversions.go b/src/cmd/compile/internal/types2/conversions.go index 4d0ed79c38..5798bacca7 100644 --- a/src/cmd/compile/internal/types2/conversions.go +++ b/src/cmd/compile/internal/types2/conversions.go @@ -49,8 +49,15 @@ func (check *Checker) conversion(x *operand, T Type) { // converted. ok = under(T).(*TypeParam).underIs(func(u Type) bool { // t is nil if there are no specific type terms - // TODO(gri) add a cause in case of failure - return u != nil && constConvertibleTo(u, nil) + if u == nil { + cause = check.sprintf("%s does not contain specific types", T) + return false + } + if !constConvertibleTo(u, nil) { + cause = check.sprintf("cannot convert %s to %s (in %s)", x, u, T) + return false + } + return true }) x.mode = value // type parameters are not constants case x.convertibleTo(check, T, &cause): diff --git a/src/cmd/compile/internal/types2/testdata/spec/conversions.go2 b/src/cmd/compile/internal/types2/testdata/spec/conversions.go2 index 942d9c0f6f..fde332f34b 100644 --- a/src/cmd/compile/internal/types2/testdata/spec/conversions.go2 +++ b/src/cmd/compile/internal/types2/testdata/spec/conversions.go2 @@ -27,6 +27,19 @@ func _[T ~string]() { var _ T = 0 // ERROR cannot use .* as T value } +// failing const conversions of constants to type parameters report a cause +func _[ + T1 any, + T2 interface{ m() }, + T3 ~int | ~float64 | ~bool, + T4 ~int | ~string, +]() { + _ = T1(0 /* ERROR cannot convert 0 .* to T1\n\tT1 does not contain specific types */ ) + _ = T2(1 /* ERROR cannot convert 1 .* to T2\n\tT2 does not contain specific types */ ) + _ = T3(2 /* ERROR cannot convert 2 .* to T3\n\tcannot convert 2 .* to bool \(in T3\) */ ) + _ = T4(3.14 /* ERROR cannot convert 3.14 .* to T4\n\tcannot convert 3.14 .* to int \(in T4\) */ ) +} + // "x is assignable to T" // - tested via assignability tests |