go/types, types2: improved tracing output throughout (debugging support)

This change fine-tunes tracing output and adds additional
descriptions for delayed actions that were missing tracing.

Change-Id: Ib5e70e8f40ef564194cdb0e8d12c38e15388b987
Reviewed-on: https://go-review.googlesource.com/c/go/+/387919
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

src/cmd/compile/internal/types2/call.go

@@ -64,7 +64,7 @@ func (check *Checker) instantiateSignature(pos syntax.Pos, typ *Signature, targs
 	assert(len(targs) == typ.TypeParams().Len())
 
 	if check.conf.Trace {
-		check.trace(pos, "-- instantiating %s with %s", typ, targs)
+		check.trace(pos, "-- instantiating signature %s with %s", typ, targs)
 		check.indent++
 		defer func() {
 			check.indent--
@@ -88,7 +88,7 @@ func (check *Checker) instantiateSignature(pos syntax.Pos, typ *Signature, targs
 		} else {
 			check.mono.recordInstance(check.pkg, pos, tparams, targs, xlist)
 		}
-	})
+	}).describef(pos, "verify instantiation")
 
 	return inst
 }

src/cmd/compile/internal/types2/check.go

@@ -373,11 +373,17 @@ func (check *Checker) processDelayed(top int) {
 	// this is a sufficiently bounded process.
 	for i := top; i < len(check.delayed); i++ {
 		a := &check.delayed[i]
-		if check.conf.Trace && a.desc != nil {
-			fmt.Println()
-			check.trace(a.desc.pos.Pos(), "-- "+a.desc.format, a.desc.args...)
+		if check.conf.Trace {
+			if a.desc != nil {
+				check.trace(a.desc.pos.Pos(), "-- "+a.desc.format, a.desc.args...)
+			} else {
+				check.trace(nopos, "-- delayed %p", a.f)
+			}
 		}
 		a.f() // may append to check.delayed
+		if check.conf.Trace {
+			fmt.Println()
+		}
 	}
 	assert(top <= len(check.delayed)) // stack must not have shrunk
 	check.delayed = check.delayed[:top]

src/cmd/compile/internal/types2/decl.go

@@ -716,7 +716,7 @@ func (check *Checker) funcDecl(obj *Func, decl *declInfo) {
 	if !check.conf.IgnoreFuncBodies && fdecl.Body != nil {
 		check.later(func() {
 			check.funcBody(decl, obj.name, sig, fdecl.Body, nil)
-		})
+		}).describef(obj, "func %s", obj.name)
 	}
 }
 

src/cmd/compile/internal/types2/expr.go

@@ -1214,7 +1214,7 @@ const (
 //
 func (check *Checker) rawExpr(x *operand, e syntax.Expr, hint Type, allowGeneric bool) exprKind {
 	if check.conf.Trace {
-		check.trace(e.Pos(), "expr %s", e)
+		check.trace(e.Pos(), "-- expr %s", e)
 		check.indent++
 		defer func() {
 			check.indent--
@@ -1328,7 +1328,7 @@ func (check *Checker) exprInternal(x *operand, e syntax.Expr, hint Type) exprKin
 				// but before the enclosing scope contents changes (#22992).
 				check.later(func() {
 					check.funcBody(decl, "<function literal>", sig, e.Body, iota)
-				})
+				}).describef(e, "func literal")
 			}
 			x.mode = value
 			x.typ = sig

src/cmd/compile/internal/types2/instantiate.go

@@ -61,7 +61,7 @@ func Instantiate(ctxt *Context, orig Type, targs []Type, validate bool) (Type, e
 
 // instance creates a type or function instance using the given original type
 // typ and arguments targs. For Named types the resulting instance will be
-// unexpanded.
+// unexpanded. check may be nil.
 func (check *Checker) instance(pos syntax.Pos, orig Type, targs []Type, ctxt *Context) (res Type) {
 	var h string
 	if ctxt != nil {
@@ -103,6 +103,7 @@ func (check *Checker) instance(pos syntax.Pos, orig Type, targs []Type, ctxt *Co
 		// anymore; we need to set tparams to nil.
 		sig.tparams = nil
 		res = sig
+
 	default:
 		// only types and functions can be generic
 		panic(fmt.Sprintf("%v: cannot instantiate %v", pos, orig))

src/cmd/compile/internal/types2/named.go

@@ -354,11 +354,19 @@ func (check *Checker) bestContext(ctxt *Context) *Context {
 // expandNamed ensures that the underlying type of n is instantiated.
 // The underlying type will be Typ[Invalid] if there was an error.
 func expandNamed(ctxt *Context, n *Named, instPos syntax.Pos) (tparams *TypeParamList, underlying Type, methods *methodList) {
+	check := n.check
+	if check != nil && check.conf.Trace {
+		check.trace(instPos, "-- expandNamed %s", n)
+		check.indent++
+		defer func() {
+			check.indent--
+			check.trace(instPos, "=> %s (tparams = %s, under = %s)", n, tparams.list(), underlying)
+		}()
+	}
+
 	n.orig.resolve(ctxt)
 	assert(n.orig.underlying != nil)
 
-	check := n.check
-
 	if _, unexpanded := n.orig.underlying.(*Named); unexpanded {
 		// We should only get an unexpanded underlying here during type checking
 		// (for example, in recursive type declarations).

src/cmd/compile/internal/types2/stmt.go

@@ -18,10 +18,7 @@ func (check *Checker) funcBody(decl *declInfo, name string, sig *Signature, body
 	}
 
 	if check.conf.Trace {
-		check.trace(body.Pos(), "--- %s: %s", name, sig)
-		defer func() {
-			check.trace(syntax.EndPos(body), "--- <end>")
-		}()
+		check.trace(body.Pos(), "-- %s: %s", name, sig)
 	}
 
 	// set function scope extent

src/cmd/compile/internal/types2/typeset.go

@@ -173,7 +173,7 @@ func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *_
 			pos = ityp.methods[0].pos
 		}
 
-		check.trace(pos, "type set for %s", ityp)
+		check.trace(pos, "-- type set for %s", ityp)
 		check.indent++
 		defer func() {
 			check.indent--
@@ -248,7 +248,7 @@ func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *_
 					err.errorf(mpos[other.(*Func)], "other declaration of %s", m.name)
 					check.report(&err)
 				}
-			})
+			}).describef(pos, "duplicate method check for %s", m.name)
 		}
 	}
 

src/cmd/compile/internal/types2/typexpr.go

@@ -174,7 +174,7 @@ func (check *Checker) validVarType(e syntax.Expr, typ Type) {
 				}
 			}
 		}
-	})
+	}).describef(e, "check var type %s", typ)
 }
 
 // definedType is like typ but also accepts a type name def.
@@ -372,7 +372,7 @@ func (check *Checker) typInternal(e0 syntax.Expr, def *Named) (T Type) {
 				}
 				check.errorf(e.Key, "invalid map key type %s%s", typ.key, why)
 			}
-		})
+		}).describef(e.Key, "check map key %s", typ.key)
 
 		return typ
 
@@ -409,7 +409,7 @@ func (check *Checker) typInternal(e0 syntax.Expr, def *Named) (T Type) {
 
 func (check *Checker) instantiatedType(x syntax.Expr, xlist []syntax.Expr, def *Named) (res Type) {
 	if check.conf.Trace {
-		check.trace(x.Pos(), "-- instantiating %s with %s", x, xlist)
+		check.trace(x.Pos(), "-- instantiating type %s with %s", x, xlist)
 		check.indent++
 		defer func() {
 			check.indent--
@@ -498,7 +498,7 @@ func (check *Checker) instantiatedType(x syntax.Expr, xlist []syntax.Expr, def *
 		}
 
 		check.validType(inst)
-	})
+	}).describef(x, "resolve instance %s", inst)
 
 	return inst
 }

src/cmd/compile/internal/types2/union.go

@@ -129,7 +129,7 @@ func parseUnion(check *Checker, uexpr syntax.Expr) Type {
 				check.softErrorf(tlist[i], "overlapping terms %s and %s", t, terms[j])
 			}
 		}
-	})
+	}).describef(uexpr, "check term validity %s", uexpr)
 
 	return u
 }

src/go/types/call.go

@@ -65,7 +65,7 @@ func (check *Checker) instantiateSignature(pos token.Pos, typ *Signature, targs
 	assert(len(targs) == typ.TypeParams().Len())
 
 	if trace {
-		check.trace(pos, "-- instantiating %s with %s", typ, targs)
+		check.trace(pos, "-- instantiating signature %s with %s", typ, targs)
 		check.indent++
 		defer func() {
 			check.indent--
@@ -89,7 +89,7 @@ func (check *Checker) instantiateSignature(pos token.Pos, typ *Signature, targs
 		} else {
 			check.mono.recordInstance(check.pkg, pos, tparams, targs, xlist)
 		}
-	})
+	}).describef(atPos(pos), "verify instantiation")
 
 	return inst
 }

src/go/types/check.go

@@ -381,11 +381,17 @@ func (check *Checker) processDelayed(top int) {
 	// this is a sufficiently bounded process.
 	for i := top; i < len(check.delayed); i++ {
 		a := &check.delayed[i]
-		if trace && a.desc != nil {
-			fmt.Println()
-			check.trace(a.desc.pos.Pos(), "-- "+a.desc.format, a.desc.args...)
+		if trace {
+			if a.desc != nil {
+				check.trace(a.desc.pos.Pos(), "-- "+a.desc.format, a.desc.args...)
+			} else {
+				check.trace(token.NoPos, "-- delayed %p", a.f)
+			}
 		}
 		a.f() // may append to check.delayed
+		if trace {
+			fmt.Println()
+		}
 	}
 	assert(top <= len(check.delayed)) // stack must not have shrunk
 	check.delayed = check.delayed[:top]

src/go/types/decl.go

@@ -786,7 +786,7 @@ func (check *Checker) funcDecl(obj *Func, decl *declInfo) {
 	if !check.conf.IgnoreFuncBodies && fdecl.Body != nil {
 		check.later(func() {
 			check.funcBody(decl, obj.name, sig, fdecl.Body, nil)
-		})
+		}).describef(obj, "func %s", obj.name)
 	}
 }
 

src/go/types/expr.go

@@ -1197,7 +1197,7 @@ const (
 //
 func (check *Checker) rawExpr(x *operand, e ast.Expr, hint Type, allowGeneric bool) exprKind {
 	if trace {
-		check.trace(e.Pos(), "expr %s", e)
+		check.trace(e.Pos(), "-- expr %s", e)
 		check.indent++
 		defer func() {
 			check.indent--
@@ -1305,7 +1305,7 @@ func (check *Checker) exprInternal(x *operand, e ast.Expr, hint Type) exprKind {
 				// but before the enclosing scope contents changes (#22992).
 				check.later(func() {
 					check.funcBody(decl, "<function literal>", sig, e.Body, iota)
-				})
+				}).describef(e, "func literal")
 			}
 			x.mode = value
 			x.typ = sig

src/go/types/instantiate.go

@@ -61,7 +61,7 @@ func Instantiate(ctxt *Context, orig Type, targs []Type, validate bool) (Type, e
 
 // instance creates a type or function instance using the given original type
 // typ and arguments targs. For Named types the resulting instance will be
-// unexpanded.
+// unexpanded. check may be nil.
 func (check *Checker) instance(pos token.Pos, orig Type, targs []Type, ctxt *Context) (res Type) {
 	var h string
 	if ctxt != nil {
@@ -103,6 +103,7 @@ func (check *Checker) instance(pos token.Pos, orig Type, targs []Type, ctxt *Con
 		// anymore; we need to set tparams to nil.
 		sig.tparams = nil
 		res = sig
+
 	default:
 		// only types and functions can be generic
 		panic(fmt.Sprintf("%v: cannot instantiate %v", pos, orig))

src/go/types/named.go

@@ -356,11 +356,19 @@ func (check *Checker) bestContext(ctxt *Context) *Context {
 // expandNamed ensures that the underlying type of n is instantiated.
 // The underlying type will be Typ[Invalid] if there was an error.
 func expandNamed(ctxt *Context, n *Named, instPos token.Pos) (tparams *TypeParamList, underlying Type, methods *methodList) {
+	check := n.check
+	if check != nil && trace {
+		check.trace(instPos, "-- expandNamed %s", n)
+		check.indent++
+		defer func() {
+			check.indent--
+			check.trace(instPos, "=> %s (tparams = %s, under = %s)", n, tparams.list(), underlying)
+		}()
+	}
+
 	n.orig.resolve(ctxt)
 	assert(n.orig.underlying != nil)
 
-	check := n.check
-
 	if _, unexpanded := n.orig.underlying.(*Named); unexpanded {
 		// We should only get an unexpanded underlying here during type checking
 		// (for example, in recursive type declarations).

src/go/types/stmt.go

@@ -19,10 +19,7 @@ func (check *Checker) funcBody(decl *declInfo, name string, sig *Signature, body
 	}
 
 	if trace {
-		check.trace(body.Pos(), "--- %s: %s", name, sig)
-		defer func() {
-			check.trace(body.End(), "--- <end>")
-		}()
+		check.trace(body.Pos(), "-- %s: %s", name, sig)
 	}
 
 	// set function scope extent

src/go/types/typeset.go

@@ -177,7 +177,7 @@ func computeInterfaceTypeSet(check *Checker, pos token.Pos, ityp *Interface) *_T
 			pos = ityp.methods[0].pos
 		}
 
-		check.trace(pos, "type set for %s", ityp)
+		check.trace(pos, "-- type set for %s", ityp)
 		check.indent++
 		defer func() {
 			check.indent--
@@ -248,7 +248,7 @@ func computeInterfaceTypeSet(check *Checker, pos token.Pos, ityp *Interface) *_T
 					check.errorf(atPos(pos), _DuplicateDecl, "duplicate method %s", m.name)
 					check.errorf(atPos(mpos[other.(*Func)]), _DuplicateDecl, "\tother declaration of %s", m.name) // secondary error, \t indented
 				}
-			})
+			}).describef(atPos(pos), "duplicate method check for %s", m.name)
 		}
 	}
 

src/go/types/typexpr.go

@@ -170,7 +170,7 @@ func (check *Checker) validVarType(e ast.Expr, typ Type) {
 				}
 			}
 		}
-	})
+	}).describef(e, "check var type %s", typ)
 }
 
 // definedType is like typ but also accepts a type name def.
@@ -353,7 +353,7 @@ func (check *Checker) typInternal(e0 ast.Expr, def *Named) (T Type) {
 				}
 				check.errorf(e.Key, _IncomparableMapKey, "incomparable map key type %s%s", typ.key, why)
 			}
-		})
+		}).describef(e.Key, "check map key %s", typ.key)
 
 		return typ
 
@@ -390,7 +390,7 @@ func (check *Checker) typInternal(e0 ast.Expr, def *Named) (T Type) {
 func (check *Checker) instantiatedType(ix *typeparams.IndexExpr, def *Named) (res Type) {
 	pos := ix.X.Pos()
 	if trace {
-		check.trace(pos, "-- instantiating %s with %s", ix.X, ix.Indices)
+		check.trace(pos, "-- instantiating type %s with %s", ix.X, ix.Indices)
 		check.indent++
 		defer func() {
 			check.indent--
@@ -483,7 +483,7 @@ func (check *Checker) instantiatedType(ix *typeparams.IndexExpr, def *Named) (re
 		}
 
 		check.validType(inst)
-	})
+	}).describef(ix, "resolve instance %s", inst)
 
 	return inst
 }

src/go/types/union.go

@@ -132,7 +132,7 @@ func parseUnion(check *Checker, uexpr ast.Expr) Type {
 				check.softErrorf(tlist[i], _InvalidUnion, "overlapping terms %s and %s", t, terms[j])
 			}
 		}
-	})
+	}).describef(uexpr, "check term validity %s", uexpr)
 
 	return u
 }