hcl: Include Expression reference in diagnostics

If a diagnostic occurs while we're evaluating an expression, we'll now
include a reference to that expression in the diagnostic object. We
previously added the corresponding EvalContext here too, and so with these
together it is now possible for a diagnostic renderer to see not only
what was in scope when the problem occurred but also what parts of that
scope the expression was relying on (via method Expression.Variables).

ext/dynblock/expand_spec.go

@@ -47,6 +47,7 @@ func (b *expandBody) decodeSpec(blockS *hcl.BlockHeaderSchema, rawSpec *hcl.Bloc
  Summary: "Invalid dynamic for_each value",
  Detail: fmt.Sprintf("Cannot use a value of type %s in for_each. An iterable collection is required.", eachVal.Type()),
  Subject: eachAttr.Expr.Range().Ptr(),
+ Expression: eachAttr.Expr,
  EvalContext: b.forEachCtx,
  })
  return nil, diags
@@ -57,6 +58,7 @@ func (b *expandBody) decodeSpec(blockS *hcl.BlockHeaderSchema, rawSpec *hcl.Bloc
  Summary: "Invalid dynamic for_each value",
  Detail: "Cannot use a null value in for_each.",
  Subject: eachAttr.Expr.Range().Ptr(),
+ Expression: eachAttr.Expr,
  EvalContext: b.forEachCtx,
  })
  return nil, diags
@@ -165,6 +167,7 @@ func (s *expandSpec) newBlock(i *iteration, ctx *hcl.EvalContext) (*hcl.Block, h
  Summary: "Invalid dynamic block label",
  Detail: fmt.Sprintf("Cannot use this value as a dynamic block label: %s.", convErr),
  Subject: labelExpr.Range().Ptr(),
+ Expression: labelExpr,
  EvalContext: lCtx,
  })
  return nil, diags
@@ -175,6 +178,7 @@ func (s *expandSpec) newBlock(i *iteration, ctx *hcl.EvalContext) (*hcl.Block, h
  Summary: "Invalid dynamic block label",
  Detail: "Cannot use a null value as a dynamic block label.",
  Subject: labelExpr.Range().Ptr(),
+ Expression: labelExpr,
  EvalContext: lCtx,
  })
  return nil, diags
@@ -185,6 +189,7 @@ func (s *expandSpec) newBlock(i *iteration, ctx *hcl.EvalContext) (*hcl.Block, h
  Summary: "Invalid dynamic block label",
  Detail: "This value is not yet known. Dynamic block labels must be immediately-known values.",
  Subject: labelExpr.Range().Ptr(),
+ Expression: labelExpr,
  EvalContext: lCtx,
  })
  return nil, diags

hcl/diagnostic.go

@@ -46,22 +46,22 @@ type Diagnostic struct {
  Subject *Range
  Context *Range
 
- // For diagnostics that occur when evaluating an expression, EvalContext
- // may point to the EvalContext that was active when evaluating that
- // expression, which may allow for the inclusion of additional useful
- // information when rendering a diagnostic message to the user.
+ // For diagnostics that occur when evaluating an expression, Expression
+ // may refer to that expression and EvalContext may point to the
+ // EvalContext that was active when evaluating it. This may allow for the
+ // inclusion of additional useful information when rendering a diagnostic
+ // message to the user.
  //
  // It is not always possible to select a single EvalContext for a
  // diagnostic, and so in some cases this field may be nil even when an
- // expression causes a problem. Therefore it is not valid to use the
- // nil-ness of this field to definitively decide whether a diagnostic
- // relates to an expression.
+ // expression causes a problem.
  //
  // EvalContexts form a tree, so the given EvalContext may refer to a parent
  // which in turn refers to another parent, etc. For a full picture of all
  // of the active variables and functions the caller must walk up this
  // chain, preferring definitions that are "closer" to the expression in
  // case of colliding names.
+ Expression Expression
  EvalContext *EvalContext
 }
 

hcl/hclsyntax/diagnostics.go

@@ -13,9 +13,10 @@ import (
 // been seen by a caller. Its purpose is to apply additional context to a
 // set of diagnostics produced by a "deeper" component as the stack unwinds
 // during expression evaluation.
-func setDiagEvalContext(diags hcl.Diagnostics, ctx *hcl.EvalContext) {
+func setDiagEvalContext(diags hcl.Diagnostics, expr hcl.Expression, ctx *hcl.EvalContext) {
  for _, diag := range diags {
- if diag.EvalContext == nil {
+ if diag.Expression == nil {
+ diag.Expression = expr
  diag.EvalContext = ctx
  }
  }

hcl/hclsyntax/expression.go

@@ -106,7 +106,7 @@ func (e *ScopeTraversalExpr) walkChildNodes(w internalWalkFunc) {
 
 func (e *ScopeTraversalExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
  val, diags := e.Traversal.TraverseAbs(ctx)
- setDiagEvalContext(diags, ctx)
+ setDiagEvalContext(diags, e, ctx)
  return val, diags
 }
 
@@ -138,7 +138,7 @@ func (e *RelativeTraversalExpr) walkChildNodes(w internalWalkFunc) {
 func (e *RelativeTraversalExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
  src, diags := e.Source.Value(ctx)
  ret, travDiags := e.Traversal.TraverseRel(src)
- setDiagEvalContext(travDiags, ctx)
+ setDiagEvalContext(travDiags, e, ctx)
  diags = append(diags, travDiags...)
  return ret, diags
 }
@@ -214,6 +214,7 @@ func (e *FunctionCallExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnosti
  Summary: "Function calls not allowed",
  Detail: "Functions may not be called here.",
  Subject: e.Range().Ptr(),
+ Expression: e,
  EvalContext: ctx,
  },
  }
@@ -235,6 +236,7 @@ func (e *FunctionCallExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnosti
  Detail: fmt.Sprintf("There is no function named %q.%s", e.Name, suggestion),
  Subject: &e.NameRange,
  Context: e.Range().Ptr(),
+ Expression: e,
  EvalContext: ctx,
  },
  }
@@ -263,8 +265,9 @@ func (e *FunctionCallExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnosti
  Severity: hcl.DiagError,
  Summary: "Invalid expanding argument value",
  Detail: "The expanding argument (indicated by ...) must not be null.",
- Context: expandExpr.Range().Ptr(),
- Subject: e.Range().Ptr(),
+ Subject: expandExpr.Range().Ptr(),
+ Context: e.Range().Ptr(),
+ Expression: expandExpr,
  EvalContext: ctx,
  })
  return cty.DynamicVal, diags
@@ -289,8 +292,9 @@ func (e *FunctionCallExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnosti
  Severity: hcl.DiagError,
  Summary: "Invalid expanding argument value",
  Detail: "The expanding argument (indicated by ...) must be of a tuple, list, or set type.",
- Context: expandExpr.Range().Ptr(),
- Subject: e.Range().Ptr(),
+ Subject: expandExpr.Range().Ptr(),
+ Context: e.Range().Ptr(),
+ Expression: expandExpr,
  EvalContext: ctx,
  })
  return cty.DynamicVal, diags
@@ -313,6 +317,7 @@ func (e *FunctionCallExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnosti
  ),
  Subject: &e.CloseParenRange,
  Context: e.Range().Ptr(),
+ Expression: e,
  EvalContext: ctx,
  },
  }
@@ -329,6 +334,7 @@ func (e *FunctionCallExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnosti
  ),
  Subject: args[len(params)].StartRange().Ptr(),
  Context: e.Range().Ptr(),
+ Expression: e,
  EvalContext: ctx,
  },
  }
@@ -361,6 +367,7 @@ func (e *FunctionCallExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnosti
  ),
  Subject: argExpr.StartRange().Ptr(),
  Context: e.Range().Ptr(),
+ Expression: argExpr,
  EvalContext: ctx,
  })
  }
@@ -399,6 +406,7 @@ func (e *FunctionCallExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnosti
  ),
  Subject: argExpr.StartRange().Ptr(),
  Context: e.Range().Ptr(),
+ Expression: argExpr,
  EvalContext: ctx,
  })
 
@@ -412,6 +420,7 @@ func (e *FunctionCallExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnosti
  ),
  Subject: e.StartRange().Ptr(),
  Context: e.Range().Ptr(),
+ Expression: e,
  EvalContext: ctx,
  })
  }
@@ -481,6 +490,7 @@ func (e *ConditionalExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostic
  ),
  Subject: hcl.RangeBetween(e.TrueResult.Range(), e.FalseResult.Range()).Ptr(),
  Context: &e.SrcRange,
+ Expression: e,
  EvalContext: ctx,
  },
  }
@@ -495,6 +505,7 @@ func (e *ConditionalExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostic
  Detail: "The condition value is null. Conditions must either be true or false.",
  Subject: e.Condition.Range().Ptr(),
  Context: &e.SrcRange,
+ Expression: e.Condition,
  EvalContext: ctx,
  })
  return cty.UnknownVal(resultType), diags
@@ -510,6 +521,7 @@ func (e *ConditionalExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostic
  Detail: fmt.Sprintf("The condition expression must be of type bool."),
  Subject: e.Condition.Range().Ptr(),
  Context: &e.SrcRange,
+ Expression: e.Condition,
  EvalContext: ctx,
  })
  return cty.UnknownVal(resultType), diags
@@ -531,6 +543,7 @@ func (e *ConditionalExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostic
  ),
  Subject: e.TrueResult.Range().Ptr(),
  Context: &e.SrcRange,
+ Expression: e.TrueResult,
  EvalContext: ctx,
  })
  trueResult = cty.UnknownVal(resultType)
@@ -551,8 +564,9 @@ func (e *ConditionalExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostic
  "The false result value has the wrong type: %s.",
  err.Error(),
  ),
- Subject: e.TrueResult.Range().Ptr(),
+ Subject: e.FalseResult.Range().Ptr(),
  Context: &e.SrcRange,
+ Expression: e.FalseResult,
  EvalContext: ctx,
  })
  falseResult = cty.UnknownVal(resultType)
@@ -697,6 +711,7 @@ func (e *ObjectConsExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics
  Summary: "Null value as key",
  Detail: "Can't use a null value as a key.",
  Subject: item.ValueExpr.Range().Ptr(),
+ Expression: item.KeyExpr,
  EvalContext: ctx,
  })
  known = false
@@ -711,6 +726,7 @@ func (e *ObjectConsExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics
  Summary: "Incorrect key type",
  Detail: fmt.Sprintf("Can't use this value as a key: %s.", err.Error()),
  Subject: item.ValueExpr.Range().Ptr(),
+ Expression: item.ValueExpr,
  EvalContext: ctx,
  })
  known = false

hcl/hclsyntax/expression_ops.go

@@ -154,6 +154,7 @@ func (e *BinaryOpExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics)
  Detail: fmt.Sprintf("Unsuitable value for left operand: %s.", err),
  Subject: e.LHS.Range().Ptr(),
  Context: &e.SrcRange,
+ Expression: e.LHS,
  EvalContext: ctx,
  })
  }
@@ -165,6 +166,7 @@ func (e *BinaryOpExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics)
  Detail: fmt.Sprintf("Unsuitable value for right operand: %s.", err),
  Subject: e.RHS.Range().Ptr(),
  Context: &e.SrcRange,
+ Expression: e.RHS,
  EvalContext: ctx,
  })
  }
@@ -184,6 +186,7 @@ func (e *BinaryOpExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics)
  Summary: "Operation failed",
  Detail: fmt.Sprintf("Error during operation: %s.", err),
  Subject: &e.SrcRange,
+ Expression: e,
  EvalContext: ctx,
  })
  return cty.UnknownVal(e.Op.Type), diags
@@ -227,6 +230,7 @@ func (e *UnaryOpExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
  Detail: fmt.Sprintf("Unsuitable value for unary operand: %s.", err),
  Subject: e.Val.Range().Ptr(),
  Context: &e.SrcRange,
+ Expression: e.Val,
  EvalContext: ctx,
  })
  }
@@ -246,6 +250,7 @@ func (e *UnaryOpExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
  Summary: "Operation failed",
  Detail: fmt.Sprintf("Error during operation: %s.", err),
  Subject: &e.SrcRange,
+ Expression: e,
  EvalContext: ctx,
  })
  return cty.UnknownVal(e.Op.Type), diags

hcl/hclsyntax/expression_template.go

@@ -39,6 +39,7 @@ func (e *TemplateExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics)
  ),
  Subject: part.Range().Ptr(),
  Context: &e.SrcRange,
+ Expression: part,
  EvalContext: ctx,
  })
  continue
@@ -64,6 +65,7 @@ func (e *TemplateExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics)
  ),
  Subject: part.Range().Ptr(),
  Context: &e.SrcRange,
+ Expression: part,
  EvalContext: ctx,
  })
  continue
@@ -130,6 +132,7 @@ func (e *TemplateJoinExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnosti
  "An iteration result is null. Cannot include a null value in a string template.",
  ),
  Subject: e.Range().Ptr(),
+ Expression: e,
  EvalContext: ctx,
  })
  continue
@@ -147,6 +150,7 @@ func (e *TemplateJoinExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnosti
  err.Error(),
  ),
  Subject: e.Range().Ptr(),
+ Expression: e,
  EvalContext: ctx,
  })
  continue

hcl/json/structure.go

@@ -432,7 +432,8 @@ func (e *expression) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
  Value: jsonAttr.Name,
  SrcRange: jsonAttr.NameRange,
  }}).Value(ctx)
- val, valDiags := (&expression{src: jsonAttr.Value}).Value(ctx)
+ valExpr := &expression{src: jsonAttr.Value}
+ val, valDiags := valExpr.Value(ctx)
  diags = append(diags, nameDiags...)
  diags = append(diags, valDiags...)
 
@@ -444,6 +445,7 @@ func (e *expression) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
  Summary: "Invalid object key expression",
  Detail: fmt.Sprintf("Cannot use this expression as an object key: %s.", err),
  Subject: &jsonAttr.NameRange,
+ Expression: valExpr,
  EvalContext: ctx,
  })
  continue
@@ -454,6 +456,7 @@ func (e *expression) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
  Summary: "Invalid object key expression",
  Detail: "Cannot use null value as an object key.",
  Subject: &jsonAttr.NameRange,
+ Expression: valExpr,
  EvalContext: ctx,
  })
  continue
@@ -477,6 +480,7 @@ func (e *expression) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
  Summary: "Duplicate object attribute",
  Detail: fmt.Sprintf("An attribute named %q was already defined at %s.", nameStr, attrRanges[nameStr]),
  Subject: &jsonAttr.NameRange,
+ Expression: e,
  EvalContext: ctx,
  })
  continue