mirror of
https://github.com/golang/go
synced 2024-11-21 14:54:40 -07:00
update type switch to match spec.
R=ken OCL=34471 CL=34471
This commit is contained in:
Russ Cox
parent
5438be4541
commit
5d16d23362
@ -4367,7 +4367,6 @@ The following minimal alignment properties are guaranteed:
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<h2 id="Implementation_differences"><font color=red>Implementation differences - TODO</font></h2>
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<ul>
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<li><font color=red>Implementation does not honor the restriction on goto statements and targets (no intervening declarations).</font></li>
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<li><font color=red>A type switch must have an assignment in the guard expression and does not support multiple types per case.</font></li>
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</ul>
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</div>
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@ -375,7 +375,7 @@ enum
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OSELECT,
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OSWITCH,
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OTYPECASE,
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OTYPESW,
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OTYPESW, // l = r.(type)
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// types
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OTCHAN,
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@ -676,7 +676,8 @@ EXTERN Node* curfn;
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EXTERN int maxround;
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EXTERN int widthptr;
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EXTERN Node* typeswvar;
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EXTERN Node* typesw;
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EXTERN Node* nblank;
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EXTERN char* structpkg;
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extern int thechar;
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@ -191,7 +191,7 @@ import_stmt:
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my->lastlineno = $1;
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import->block = 1; // at top level
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}
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import_stmt_list:
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import_stmt
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@ -230,10 +230,10 @@ import_package:
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pkgimportname = $2;
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if(strcmp($2->name, "main") == 0)
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yyerror("cannot import package main");
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// TODO(rsc): This is not quite precise enough a check
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// (it excludes google/util/hash from importing hash)
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// but it is enough to reduce confusion during the
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// but it is enough to reduce confusion during the
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// 2009/09/01 release when all the "import myself"
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// statements have to go away in programs building
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// against the release. Once the programs have converted
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@ -424,7 +424,7 @@ simple_stmt:
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yyerror("expr.(type) must be alone in list");
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else if($1->next != nil)
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yyerror("argument count mismatch: %d = %d", count($1), 1);
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$$ = nod(OTYPESW, $1->n, $3->n->left);
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$$ = nod(OTYPESW, $1->n, $3->n->right);
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break;
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}
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$$ = colas($1, $3);
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@ -443,30 +443,19 @@ simple_stmt:
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case:
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LCASE expr_or_type_list ':'
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{
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Node *n, *ntype;
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Node *n;
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// will be converted to OCASE
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// right will point to next case
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// done in casebody()
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poptodcl();
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$$ = nod(OXCASE, N, N);
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if(typeswvar != N && typeswvar->right != N) {
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// type switch
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ntype = $2->n;
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if($2->next != nil)
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yyerror("type switch case cannot be list");
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if(ntype->op == OLITERAL && ntype->val.ctype == CTNIL) {
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// case nil
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$$->list = list1(nod(OTYPECASE, N, N));
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break;
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}
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n = newname(typeswvar->right->sym);
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$$->list = $2;
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if(typesw != N && typesw->right != N && (n=typesw->right->left) != N) {
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// type switch - declare variable
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n = newname(n->sym);
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declare(n, dclcontext);
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n->ntype = ntype;
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$$->list = list1(nod(OTYPECASE, n, N));
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} else {
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// expr switch
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$$->list = $2;
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$$->nname = n;
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}
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break;
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}
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@ -490,8 +479,16 @@ case:
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}
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| LDEFAULT ':'
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{
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Node *n;
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poptodcl();
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$$ = nod(OXCASE, N, N);
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if(typesw != N && typesw->right != N && (n=typesw->right->left) != N) {
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// type switch - declare variable
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n = newname(n->sym);
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declare(n, dclcontext);
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$$->nname = n;
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}
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}
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compound_stmt:
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@ -637,18 +634,16 @@ switch_stmt:
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{
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Node *n;
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n = $3->ntest;
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if(n != N && n->op == OTYPESW)
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n = n->left;
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else
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if(n != N && n->op != OTYPESW)
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n = N;
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typeswvar = nod(OXXX, typeswvar, n);
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typesw = nod(OXXX, typesw, n);
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}
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switch_body
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{
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$$ = $3;
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$$->op = OSWITCH;
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$$->list = $5;
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typeswvar = typeswvar->left;
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typesw = typesw->left;
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popdcl();
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}
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@ -823,7 +818,7 @@ pexpr:
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}
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| pexpr '.' '(' LTYPE ')'
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{
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$$ = nod(OTYPESW, $1, N);
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$$ = nod(OTYPESW, N, $1);
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}
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| pexpr '[' expr ']'
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{
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@ -1289,20 +1284,14 @@ arg_type:
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name_or_type
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| sym name_or_type
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{
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$$ = $1->def;
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if($$ == N) {
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$$ = nod(ONONAME, N, N);
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$$->sym = $1;
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}
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$$ = nod(ONONAME, N, N);
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$$->sym = $1;
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$$ = nod(OKEY, $$, $2);
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}
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| sym dotdotdot
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{
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$$ = $1->def;
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if($$ == N) {
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$$ = nod(ONONAME, N, N);
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$$->sym = $1;
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}
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$$ = nod(ONONAME, N, N);
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$$->sym = $1;
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$$ = nod(OKEY, $$, $2);
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}
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| dotdotdot
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@ -1359,6 +1359,7 @@ lexinit(void)
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s->def->sym = s;
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types[TBLANK] = typ(TBLANK);
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s->def->type = types[TBLANK];
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nblank = s->def;
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}
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struct
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@ -249,13 +249,13 @@ newlabel(void)
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* deal with fallthrough, break, unreachable statements
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*/
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void
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casebody(Node *sw)
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casebody(Node *sw, Node *typeswvar)
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{
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Node *os, *oc, *n, *c, *last;
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Node *def;
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NodeList *cas, *stat, *l, *lc;
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Node *go, *br;
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int32 lno;
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int32 lno, needvar;
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lno = setlineno(sw);
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if(sw->list == nil)
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@ -274,6 +274,7 @@ casebody(Node *sw)
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if(n->op != OXCASE)
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fatal("casebody %O", n->op);
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n->op = OCASE;
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needvar = count(n->list) != 1 || n->list->n->op == OLITERAL;
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go = nod(OGOTO, newlabel(), N);
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if(n->list == nil) {
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@ -300,6 +301,14 @@ casebody(Node *sw)
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}
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stat = list(stat, nod(OLABEL, go->left, N));
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if(typeswvar && needvar && n->nname != N) {
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NodeList *l;
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l = list1(nod(ODCL, n->nname, N));
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l = list(l, nod(OAS, n->nname, typeswvar));
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typechecklist(l, Etop);
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stat = concat(stat, l);
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}
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stat = concat(stat, n->nbody);
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// botch - shouldnt fall thru declaration
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@ -348,16 +357,16 @@ mkcaselist(Node *sw, int arg)
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switch(arg) {
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case Stype:
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c->hash = 0;
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if(n->left->left == N) {
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if(n->left->op == OLITERAL) {
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c->type = Ttypenil;
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continue;
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}
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if(istype(n->left->left->type, TINTER)) {
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if(istype(n->left->type, TINTER)) {
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c->type = Ttypevar;
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continue;
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}
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c->hash = typehash(n->left->left->type);
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c->hash = typehash(n->left->type);
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c->type = Ttypeconst;
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continue;
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@ -483,6 +492,7 @@ exprswitch(Node *sw)
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Type *t;
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int arg, ncase;
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casebody(sw, N);
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arg = Snorm;
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if(isconst(sw->ntest, CTBOOL)) {
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@ -564,13 +574,18 @@ typeone(Node *t)
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NodeList *init;
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Node *a, *b, *var;
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var = t->left->left;
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init = list1(nod(ODCL, var, N));
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var = t->nname;
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init = nil;
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if(var == N) {
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typecheck(&nblank, Erv | Easgn);
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var = nblank;
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} else
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init = list1(nod(ODCL, var, N));
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a = nod(OAS2, N, N);
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a->list = list(list1(var), boolname); // var,bool =
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b = nod(ODOTTYPE, facename, N);
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b->type = t->left->left->type; // interface.(type)
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b->type = t->left->type; // interface.(type)
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a->rlist = list1(b);
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typecheck(&a, Etop);
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init = list(init, a);
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@ -678,6 +693,8 @@ typeswitch(Node *sw)
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typecheck(&a, Etop);
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cas = list(cas, a);
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casebody(sw, facename);
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boolname = nod(OXXX, N, N);
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tempname(boolname, types[TBOOL]);
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typecheck(&boolname, Erv);
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@ -758,10 +775,10 @@ walkswitch(Node *sw)
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sw->ntest = nodbool(1);
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typecheck(&sw->ntest, Erv);
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}
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casebody(sw);
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if(sw->ntest->op == OTYPESW) {
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typeswitch(sw);
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//dump("sw", sw);
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return;
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}
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exprswitch(sw);
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@ -776,7 +793,7 @@ typecheckswitch(Node *n)
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int top, lno;
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Type *t;
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NodeList *l, *ll;
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Node *ncase;
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Node *ncase, *nvar;
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Node *def;
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lno = lineno;
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@ -784,11 +801,11 @@ typecheckswitch(Node *n)
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if(n->ntest != N && n->ntest->op == OTYPESW) {
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// type switch
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typecheck(&n->ntest, Etop);
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top = Etype;
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t = n->ntest->type;
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typecheck(&n->ntest->right, Erv);
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t = n->ntest->right->type;
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if(t != T && t->etype != TINTER)
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yyerror("cannot type switch on non-interface value %+N", n->ntest);
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yyerror("cannot type switch on non-interface value %+N", n->ntest->right);
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} else {
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// value switch
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top = Erv;
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@ -814,12 +831,37 @@ typecheckswitch(Node *n)
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} else {
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for(ll=ncase->list; ll; ll=ll->next) {
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setlineno(ll->n);
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typecheck(&ll->n, Erv); // TODO(rsc): top
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if(ll->n->type == T || t == T || top != Erv)
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typecheck(&ll->n, Erv | Etype);
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if(ll->n->type == T || t == T)
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continue;
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defaultlit(&ll->n, t);
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if(ll->n->type != T && !eqtype(ll->n->type, t))
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yyerror("case %+N in switch of %+N %#O", ll->n, n->ntest, ll->n->op);
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switch(top) {
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case Erv: // expression switch
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defaultlit(&ll->n, t);
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if(ll->n->op == OTYPE)
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yyerror("type %T is not an expression", ll->n->type);
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else if(ll->n->type != T && !eqtype(ll->n->type, t))
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yyerror("case %+N in switch of %+N %#O", ll->n, n->ntest, ll->n->op);
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break;
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case Etype: // type switch
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if(ll->n->op == OLITERAL && istype(ll->n->type, TNIL))
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;
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else if(ll->n->op != OTYPE && ll->n->type != T)
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yyerror("%#N is not a type", ll->n);
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break;
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}
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}
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}
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if(top == Etype && n->type != T) {
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ll = ncase->list;
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nvar = ncase->nname;
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if(nvar != N) {
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if(ll && ll->next == nil && ll->n->type != T && !istype(ll->n->type, TNIL)) {
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// single entry type switch
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nvar->ntype = typenod(ll->n->type);
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} else {
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// multiple entry type switch or default
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nvar->ntype = typenod(n->type);
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}
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}
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}
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typechecklist(ncase->nbody, Etop);
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@ -415,7 +415,7 @@ func (s *State) error(msg string) {
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//
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func typename(typ reflect.Type) string {
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switch t := typ.(type) {
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switch typ.(type) {
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case *reflect.ArrayType:
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return "array";
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case *reflect.SliceType:
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@ -19,12 +19,8 @@ type _StructBuilder struct {
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var nobuilder *_StructBuilder
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func isfloat(v reflect.Value) bool {
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switch v := v.(type) {
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case *reflect.FloatValue:
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return true;
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case *reflect.Float32Value:
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return true;
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case *reflect.Float64Value:
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switch v.(type) {
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case *reflect.FloatValue, *reflect.Float32Value, *reflect.Float64Value:
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return true;
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}
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return false;
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84
test/typeswitch1.go
Normal file
84
test/typeswitch1.go
Normal file
@ -0,0 +1,84 @@
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// $G $D/$F.go && $L $F.$A && ./$A.out
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package main
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import "fmt"
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const (
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a = iota;
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b;
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c;
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d;
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e;
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)
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var x = []int{1,2,3}
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func f(x int, len *byte) {
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*len = byte(x);
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}
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func whatis(x interface{}) string {
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switch xx := x.(type) {
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default:
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return fmt.Sprint("default ", xx);
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case int, int8, int16, int32:
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return fmt.Sprint("signed ", xx);
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case int64:
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return fmt.Sprint("signed64 ", int64(xx));
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case uint, uint8, uint16, uint32:
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return fmt.Sprint("unsigned ", xx);
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case uint64:
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return fmt.Sprint("unsigned64 ", uint64(xx));
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case nil:
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return fmt.Sprint("nil ", xx);
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}
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panic("not reached");
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}
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func whatis1(x interface{}) string {
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xx := x;
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switch xx.(type) {
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default:
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return fmt.Sprint("default ", xx);
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case int, int8, int16, int32:
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return fmt.Sprint("signed ", xx);
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case int64:
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return fmt.Sprint("signed64 ", xx.(int64));
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case uint, uint8, uint16, uint32:
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return fmt.Sprint("unsigned ", xx);
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case uint64:
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return fmt.Sprint("unsigned64 ", xx.(uint64));
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case nil:
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return fmt.Sprint("nil ", xx);
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}
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panic("not reached");
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}
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func check(x interface{}, s string) {
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w := whatis(x);
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if w != s {
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fmt.Println("whatis", x, "=>", w, "!=", s);
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panic();
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}
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w = whatis1(x);
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if w != s {
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fmt.Println("whatis1", x, "=>", w, "!=", s);
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panic();
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}
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}
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func main() {
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check(1, "signed 1");
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check(uint(1), "unsigned 1");
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check(int64(1), "signed64 1");
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check(uint64(1), "unsigned64 1");
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check(1.5, "default 1.5");
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check(nil, "nil <nil>");
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}
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