cmd/compile/internal/types2: record types for union subexpressions

This is a port of CL 371757 from go/types to types2, with
minor adjustments for different error handling and AST.

It also names the added API test cases more consistently.
The same renaming was applied to the respective go/types
file.

Updates #50093

Change-Id: Iaa132106a197a207f831525432e62e9d452b17c9
Reviewed-on: https://go-review.googlesource.com/c/go/+/372475
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

diff --git a/src/cmd/compile/internal/types2/api.go b/src/cmd/compile/internal/types2/api.go
index ed5bced643428dc852cb4eb6fc134132e7e1da2a..4ea3989c39577c4df32a72755e01a045bd3c3937 100644 (file)
--- a/src/cmd/compile/internal/types2/api.go
+++ b/src/cmd/compile/internal/types2/api.go
@@ -202,12 +202,6 @@ type Info struct {
        // identifier z in a variable declaration 'var z int' is found
        // only in the Defs map, and identifiers denoting packages in
        // qualified identifiers are collected in the Uses map.
-       //
-       // For binary expressions representing unions in constraint
-       // position or type elements in interfaces, a union type is
-       // recorded for the top-level expression only. For instance,
-       // given the constraint a|b|c, the union type for (a|b)|c
-       // is recorded, but not the union type for a|b.
        Types map[syntax.Expr]TypeAndValue
 
        // Instances maps identifiers denoting parameterized types or functions to

diff --git a/src/cmd/compile/internal/types2/api_test.go b/src/cmd/compile/internal/types2/api_test.go
index fc8b5cd4ee01edbf48e13a1d8368e2f1ebbef273..dee7ffbaf7ad00807737543c856d0a7154926989 100644 (file)
--- a/src/cmd/compile/internal/types2/api_test.go
+++ b/src/cmd/compile/internal/types2/api_test.go
@@ -348,10 +348,25 @@ func TestTypesInfo(t *testing.T) {
                {`package u1a; func _[_ interface{~int}]() {}`, `~int`, `~int`},
                {`package u2a; func _[_ interface{int|string}]() {}`, `int | string`, `int|string`},
                {`package u3a; func _[_ interface{int|string|~bool}]() {}`, `int | string | ~bool`, `int|string|~bool`},
+               {`package u3a; func _[_ interface{int|string|~bool}]() {}`, `int | string`, `int|string`},
+               {`package u3a; func _[_ interface{int|string|~bool}]() {}`, `~bool`, `~bool`},
+               {`package u3a; func _[_ interface{int|string|~float64|~bool}]() {}`, `int | string | ~float64`, `int|string|~float64`},
+
                {`package u0b; func _[_ int]() {}`, `int`, `int`},
                {`package u1b; func _[_ ~int]() {}`, `~int`, `~int`},
                {`package u2b; func _[_ int|string]() {}`, `int | string`, `int|string`},
                {`package u3b; func _[_ int|string|~bool]() {}`, `int | string | ~bool`, `int|string|~bool`},
+               {`package u3b; func _[_ int|string|~bool]() {}`, `int | string`, `int|string`},
+               {`package u3b; func _[_ int|string|~bool]() {}`, `~bool`, `~bool`},
+               {`package u3b; func _[_ int|string|~float64|~bool]() {}`, `int | string | ~float64`, `int|string|~float64`},
+
+               {`package u0c; type _ interface{int}`, `int`, `int`},
+               {`package u1c; type _ interface{~int}`, `~int`, `~int`},
+               {`package u2c; type _ interface{int|string}`, `int | string`, `int|string`},
+               {`package u3c; type _ interface{int|string|~bool}`, `int | string | ~bool`, `int|string|~bool`},
+               {`package u3c; type _ interface{int|string|~bool}`, `int | string`, `int|string`},
+               {`package u3c; type _ interface{int|string|~bool}`, `~bool`, `~bool`},
+               {`package u3c; type _ interface{int|string|~float64|~bool}`, `int | string | ~float64`, `int|string|~float64`},
        }
 
        for _, test := range tests {

diff --git a/src/cmd/compile/internal/types2/union.go b/src/cmd/compile/internal/types2/union.go
index 98dd6cedc7a22dc6eba35780cb0107d08e7e976d..6f66260af4618963cdb4b4f85f4fba35d3039195 100644 (file)
--- a/src/cmd/compile/internal/types2/union.go
+++ b/src/cmd/compile/internal/types2/union.go
@@ -48,23 +48,37 @@ const maxTermCount = 100
 // parseUnion parses uexpr as a union of expressions.
 // The result is a Union type, or Typ[Invalid] for some errors.
 func parseUnion(check *Checker, uexpr syntax.Expr) Type {
-       tlist := flattenUnion(nil, uexpr)
+       blist, tlist := flattenUnion(nil, uexpr)
+       assert(len(blist) == len(tlist)-1)
 
        var terms []*Term
-       for _, x := range tlist {
-               tilde, typ := parseTilde(check, x)
-               if len(tlist) == 1 && !tilde {
+
+       var u Type
+       for i, x := range tlist {
+               term := parseTilde(check, x)
+               if len(tlist) == 1 && !term.tilde {
                        // Single type. Ok to return early because all relevant
                        // checks have been performed in parseTilde (no need to
                        // run through term validity check below).
-                       return typ // typ already recorded through check.typ in parseTilde
+                       return term.typ // typ already recorded through check.typ in parseTilde
                }
                if len(terms) >= maxTermCount {
-                       check.errorf(x, "cannot handle more than %d union terms (implementation limitation)", maxTermCount)
-                       check.recordTypeAndValue(uexpr, typexpr, Typ[Invalid], nil)
-                       return Typ[Invalid]
+                       if u != Typ[Invalid] {
+                               check.errorf(x, "cannot handle more than %d union terms (implementation limitation)", maxTermCount)
+                               u = Typ[Invalid]
+                       }
+               } else {
+                       terms = append(terms, term)
+                       u = &Union{terms}
+               }
+
+               if i > 0 {
+                       check.recordTypeAndValue(blist[i-1], typexpr, u, nil)
                }
-               terms = append(terms, NewTerm(tilde, typ))
+       }
+
+       if u == Typ[Invalid] {
+               return u
        }
 
        // Check validity of terms.
@@ -106,17 +120,17 @@ func parseUnion(check *Checker, uexpr syntax.Expr) Type {
                }
        })
 
-       u := &Union{terms}
-       check.recordTypeAndValue(uexpr, typexpr, u, nil)
        return u
 }
 
-func parseTilde(check *Checker, x syntax.Expr) (tilde bool, typ Type) {
+func parseTilde(check *Checker, tx syntax.Expr) *Term {
+       x := tx
+       var tilde bool
        if op, _ := x.(*syntax.Operation); op != nil && op.Op == syntax.Tilde {
                x = op.X
                tilde = true
        }
-       typ = check.typ(x)
+       typ := check.typ(x)
        // Embedding stand-alone type parameters is not permitted (issue #47127).
        // We don't need this restriction anymore if we make the underlying type of a type
        // parameter its constraint interface: if we embed a lone type parameter, we will
@@ -126,7 +140,11 @@ func parseTilde(check *Checker, x syntax.Expr) (tilde bool, typ Type) {
                check.error(x, "cannot embed a type parameter")
                typ = Typ[Invalid]
        }
-       return
+       term := NewTerm(tilde, typ)
+       if tilde {
+               check.recordTypeAndValue(tx, typexpr, &Union{[]*Term{term}}, nil)
+       }
+       return term
 }
 
 // overlappingTerm reports the index of the term x in terms which is
@@ -147,10 +165,13 @@ func overlappingTerm(terms []*Term, y *Term) int {
        return -1
 }
 
-func flattenUnion(list []syntax.Expr, x syntax.Expr) []syntax.Expr {
+// flattenUnion walks a union type expression of the form A | B | C | ...,
+// extracting both the binary exprs (blist) and leaf types (tlist).
+func flattenUnion(list []syntax.Expr, x syntax.Expr) (blist, tlist []syntax.Expr) {
        if o, _ := x.(*syntax.Operation); o != nil && o.Op == syntax.Or {
-               list = flattenUnion(list, o.X)
+               blist, tlist = flattenUnion(list, o.X)
+               blist = append(blist, o)
                x = o.Y
        }
-       return append(list, x)
+       return blist, append(tlist, x)
 }

diff --git a/src/go/types/api_test.go b/src/go/types/api_test.go
index e55255d75e21221c522ca97770708ac1b9f214d3..6a1bf269845ad64e6a16a0df588db33ce18f2b0a 100644 (file)
--- a/src/go/types/api_test.go
+++ b/src/go/types/api_test.go
@@ -379,9 +379,10 @@ func TestTypesInfo(t *testing.T) {
                {genericPkg + `u1a; func _[_ interface{~int}]() {}`, `~int`, `~int`},
                {genericPkg + `u2a; func _[_ interface{int|string}]() {}`, `int | string`, `int|string`},
                {genericPkg + `u3a; func _[_ interface{int|string|~bool}]() {}`, `int | string | ~bool`, `int|string|~bool`},
-               {genericPkg + `u3b; func _[_ interface{int|string|~bool}]() {}`, `int | string`, `int|string`},
-               {genericPkg + `u3b; func _[_ interface{int|string|~bool}]() {}`, `~bool`, `~bool`},
-               {genericPkg + `u3b; func _[_ interface{int|string|~float64|~bool}]() {}`, `int | string | ~float64`, `int|string|~float64`},
+               {genericPkg + `u3a; func _[_ interface{int|string|~bool}]() {}`, `int | string`, `int|string`},
+               {genericPkg + `u3a; func _[_ interface{int|string|~bool}]() {}`, `~bool`, `~bool`},
+               {genericPkg + `u3a; func _[_ interface{int|string|~float64|~bool}]() {}`, `int | string | ~float64`, `int|string|~float64`},
+
                {genericPkg + `u0b; func _[_ int]() {}`, `int`, `int`},
                {genericPkg + `u1b; func _[_ ~int]() {}`, `~int`, `~int`},
                {genericPkg + `u2b; func _[_ int|string]() {}`, `int | string`, `int|string`},
@@ -389,13 +390,14 @@ func TestTypesInfo(t *testing.T) {
                {genericPkg + `u3b; func _[_ int|string|~bool]() {}`, `int | string`, `int|string`},
                {genericPkg + `u3b; func _[_ int|string|~bool]() {}`, `~bool`, `~bool`},
                {genericPkg + `u3b; func _[_ int|string|~float64|~bool]() {}`, `int | string | ~float64`, `int|string|~float64`},
-               {genericPkg + `u0b; type _ interface{int}`, `int`, `int`},
-               {genericPkg + `u1b; type _ interface{~int}`, `~int`, `~int`},
-               {genericPkg + `u2b; type _ interface{int|string}`, `int | string`, `int|string`},
-               {genericPkg + `u3b; type _ interface{int|string|~bool}`, `int | string | ~bool`, `int|string|~bool`},
-               {genericPkg + `u3b; type _ interface{int|string|~bool}`, `int | string`, `int|string`},
-               {genericPkg + `u3b; type _ interface{int|string|~bool}`, `~bool`, `~bool`},
-               {genericPkg + `u3b; type _ interface{int|string|~float64|~bool}`, `int | string | ~float64`, `int|string|~float64`},
+
+               {genericPkg + `u0c; type _ interface{int}`, `int`, `int`},
+               {genericPkg + `u1c; type _ interface{~int}`, `~int`, `~int`},
+               {genericPkg + `u2c; type _ interface{int|string}`, `int | string`, `int|string`},
+               {genericPkg + `u3c; type _ interface{int|string|~bool}`, `int | string | ~bool`, `int|string|~bool`},
+               {genericPkg + `u3c; type _ interface{int|string|~bool}`, `int | string`, `int|string`},
+               {genericPkg + `u3c; type _ interface{int|string|~bool}`, `~bool`, `~bool`},
+               {genericPkg + `u3c; type _ interface{int|string|~float64|~bool}`, `int | string | ~float64`, `int|string|~float64`},
        }
 
        for _, test := range tests {