opentofu/tfdiags/hcl.go

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tfdiags: new package for normalizing error and warning messages Currently we lean heavily on the Go error type as our primary means of describing errors, and along with that use several more specialized implementations of it in different spots for additional capabilities such as multiple errors in one object, source code range references, etc. We also have a rather ad-hoc approach of returning an array of warnings from certain functions along with one or multiple errors. This rather-disorganized approach makes it hard for us to present user-facing error messages consistently. As a step towards mitigating this, package tfdiags provides a model for user-facing error and warning messages and helper functions for creating them from various other error and warning types used elsewhere in Terraform. This mechanism is intended to be used to report errors and warnings where the audience is the Terraform user, and so it may go a few layers deep down the call stack into codepaths like config parsing, interpolation, etc but is primarily a UX concern. The deepest reaches of Terraform core will continue using "error" as normal, with higher layers preparing error messages for presentation to the user. To avoid needing to change the interface of every function that might generate error diagnostics, the Diagnostics type can be "smuggled" via an error value through other APIs and then unwrapped at the other end, though it will lose any naked warnings (without at least one error) along the way, and so codepaths that are expected to generate warnings (validation, primarily) should use the concrete Diagnostics type throughout the call chain.
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package tfdiags
import (
"fmt"
"github.com/hashicorp/hcl/v2"
tfdiags: new package for normalizing error and warning messages Currently we lean heavily on the Go error type as our primary means of describing errors, and along with that use several more specialized implementations of it in different spots for additional capabilities such as multiple errors in one object, source code range references, etc. We also have a rather ad-hoc approach of returning an array of warnings from certain functions along with one or multiple errors. This rather-disorganized approach makes it hard for us to present user-facing error messages consistently. As a step towards mitigating this, package tfdiags provides a model for user-facing error and warning messages and helper functions for creating them from various other error and warning types used elsewhere in Terraform. This mechanism is intended to be used to report errors and warnings where the audience is the Terraform user, and so it may go a few layers deep down the call stack into codepaths like config parsing, interpolation, etc but is primarily a UX concern. The deepest reaches of Terraform core will continue using "error" as normal, with higher layers preparing error messages for presentation to the user. To avoid needing to change the interface of every function that might generate error diagnostics, the Diagnostics type can be "smuggled" via an error value through other APIs and then unwrapped at the other end, though it will lose any naked warnings (without at least one error) along the way, and so codepaths that are expected to generate warnings (validation, primarily) should use the concrete Diagnostics type throughout the call chain.
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)
// hclDiagnostic is a Diagnostic implementation that wraps a HCL Diagnostic
type hclDiagnostic struct {
diag *hcl.Diagnostic
}
var _ Diagnostic = hclDiagnostic{}
func (d hclDiagnostic) Severity() Severity {
switch d.diag.Severity {
case hcl.DiagWarning:
return Warning
default:
return Error
}
}
func (d hclDiagnostic) Description() Description {
return Description{
Summary: d.diag.Summary,
Detail: d.diag.Detail,
}
}
func (d hclDiagnostic) Source() Source {
var ret Source
if d.diag.Subject != nil {
rng := SourceRangeFromHCL(*d.diag.Subject)
ret.Subject = &rng
tfdiags: new package for normalizing error and warning messages Currently we lean heavily on the Go error type as our primary means of describing errors, and along with that use several more specialized implementations of it in different spots for additional capabilities such as multiple errors in one object, source code range references, etc. We also have a rather ad-hoc approach of returning an array of warnings from certain functions along with one or multiple errors. This rather-disorganized approach makes it hard for us to present user-facing error messages consistently. As a step towards mitigating this, package tfdiags provides a model for user-facing error and warning messages and helper functions for creating them from various other error and warning types used elsewhere in Terraform. This mechanism is intended to be used to report errors and warnings where the audience is the Terraform user, and so it may go a few layers deep down the call stack into codepaths like config parsing, interpolation, etc but is primarily a UX concern. The deepest reaches of Terraform core will continue using "error" as normal, with higher layers preparing error messages for presentation to the user. To avoid needing to change the interface of every function that might generate error diagnostics, the Diagnostics type can be "smuggled" via an error value through other APIs and then unwrapped at the other end, though it will lose any naked warnings (without at least one error) along the way, and so codepaths that are expected to generate warnings (validation, primarily) should use the concrete Diagnostics type throughout the call chain.
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}
if d.diag.Context != nil {
rng := SourceRangeFromHCL(*d.diag.Context)
ret.Context = &rng
tfdiags: new package for normalizing error and warning messages Currently we lean heavily on the Go error type as our primary means of describing errors, and along with that use several more specialized implementations of it in different spots for additional capabilities such as multiple errors in one object, source code range references, etc. We also have a rather ad-hoc approach of returning an array of warnings from certain functions along with one or multiple errors. This rather-disorganized approach makes it hard for us to present user-facing error messages consistently. As a step towards mitigating this, package tfdiags provides a model for user-facing error and warning messages and helper functions for creating them from various other error and warning types used elsewhere in Terraform. This mechanism is intended to be used to report errors and warnings where the audience is the Terraform user, and so it may go a few layers deep down the call stack into codepaths like config parsing, interpolation, etc but is primarily a UX concern. The deepest reaches of Terraform core will continue using "error" as normal, with higher layers preparing error messages for presentation to the user. To avoid needing to change the interface of every function that might generate error diagnostics, the Diagnostics type can be "smuggled" via an error value through other APIs and then unwrapped at the other end, though it will lose any naked warnings (without at least one error) along the way, and so codepaths that are expected to generate warnings (validation, primarily) should use the concrete Diagnostics type throughout the call chain.
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}
return ret
}
func (d hclDiagnostic) FromExpr() *FromExpr {
if d.diag.Expression == nil || d.diag.EvalContext == nil {
return nil
}
return &FromExpr{
Expression: d.diag.Expression,
EvalContext: d.diag.EvalContext,
}
}
// SourceRangeFromHCL constructs a SourceRange from the corresponding range
// type within the HCL package.
func SourceRangeFromHCL(hclRange hcl.Range) SourceRange {
return SourceRange{
Filename: hclRange.Filename,
Start: SourcePos{
Line: hclRange.Start.Line,
Column: hclRange.Start.Column,
Byte: hclRange.Start.Byte,
},
End: SourcePos{
Line: hclRange.End.Line,
Column: hclRange.End.Column,
Byte: hclRange.End.Byte,
},
}
}
// ToHCL constructs a HCL Range from the receiving SourceRange. This is the
// opposite of SourceRangeFromHCL.
func (r SourceRange) ToHCL() hcl.Range {
return hcl.Range{
Filename: r.Filename,
Start: hcl.Pos{
Line: r.Start.Line,
Column: r.Start.Column,
Byte: r.Start.Byte,
},
End: hcl.Pos{
Line: r.End.Line,
Column: r.End.Column,
Byte: r.End.Byte,
},
}
}
// ToHCL constructs a hcl.Diagnostics containing the same diagnostic messages
// as the receiving tfdiags.Diagnostics.
//
// This conversion preserves the data that HCL diagnostics are able to
// preserve but would be lossy in a round trip from tfdiags to HCL and then
// back to tfdiags, because it will lose the specific type information of
// the source diagnostics. In most cases this will not be a significant
// problem, but could produce an awkward result in some special cases such
// as converting the result of ConsolidateWarnings, which will force the
// resulting warning groups to be flattened early.
func (d Diagnostics) ToHCL() hcl.Diagnostics {
if len(d) == 0 {
return nil
}
ret := make(hcl.Diagnostics, len(d))
for i, diag := range d {
severity := diag.Severity()
desc := diag.Description()
source := diag.Source()
fromExpr := diag.FromExpr()
hclDiag := &hcl.Diagnostic{
Summary: desc.Summary,
Detail: desc.Detail,
}
switch severity {
case Warning:
hclDiag.Severity = hcl.DiagWarning
case Error:
hclDiag.Severity = hcl.DiagError
default:
// The above should always be exhaustive for all of the valid
// Severity values in this package.
panic(fmt.Sprintf("unknown diagnostic severity %s", severity))
}
if source.Subject != nil {
hclDiag.Subject = source.Subject.ToHCL().Ptr()
}
if source.Context != nil {
hclDiag.Context = source.Context.ToHCL().Ptr()
}
if fromExpr != nil {
hclDiag.Expression = fromExpr.Expression
hclDiag.EvalContext = fromExpr.EvalContext
}
ret[i] = hclDiag
}
return ret
}