check for unused imports

R=ken
OCL=34732
CL=34756

diff --git a/src/cmd/gc/go.h b/src/cmd/gc/go.h
index aa2e6d89d6534d5be5e912fe74cfa03526ac5576..2c5e2242fc32812a8c2ec9e19d9067546fd60ae4 100644 (file)
--- a/src/cmd/gc/go.h
+++ b/src/cmd/gc/go.h
@@ -236,6 +236,7 @@ struct      Node
        // ONAME
        Node*   ntype;
        Node*   defn;
+       Node*   pack;   // real package for import . names
 
        // ONAME func param with PHEAP
        Node*   heapaddr;       // temp holding heap address of param
@@ -246,7 +247,7 @@ struct      Node
        Node*   outer;  // outer PPARAMREF in nested closure
        Node*   closure;        // ONAME/PHEAP <-> ONAME/PPARAMREF
 
-       Sym*    psym;           // import
+       char*   pline;
        Sym*    sym;            // various
        int32   vargen;         // unique name for OTYPE/ONAME
        int32   lineno;
@@ -694,6 +695,7 @@ EXTERN      int     noargnames;
 EXTERN int     funcdepth;
 EXTERN int     typecheckok;
 
+EXTERN char*   importline;
 
 /*
  *     y.tab.c
@@ -704,7 +706,7 @@ int yyparse(void);
  *     lex.c
  */
 void   addidir(char*);
-void   importfile(Val*);
+void   importfile(Val*, int line);
 void   cannedimports(char*, char*);
 void   unimportfile();
 int32  yylex(void);
@@ -788,7 +790,7 @@ uint32      stringhash(char*);
 Sym*   lookup(char*);
 Sym*   pkglookup(char*, char*);
 Sym*   restrictlookup(char*, char*);
-void   importdot(Sym*);
+void   importdot(Sym*, Node*);
 void   yyerror(char*, ...);
 int    parserline(void);
 void   warn(char*, ...);

diff --git a/src/cmd/gc/go.y b/src/cmd/gc/go.y
index 7b1f772242b6a3cd8b35b027bca5a62e83157bab..af7285d4a39cde5b2f92f98335d11b4a2132cb06 100644 (file)
--- a/src/cmd/gc/go.y
+++ b/src/cmd/gc/go.y
@@ -165,6 +165,7 @@ import_stmt:
        import_here import_package import_there
        {
                Sym *import, *my;
+               Node *pack;
 
                import = pkgimportname;
                my = pkgmyname;
@@ -173,10 +174,16 @@ import_stmt:
 
                if(import == S)
                        break;
+
+               pack = nod(OPACK, N, N);
+               pack->sym = import;
+               pack->lineno = $1;
+               pack->pline = importline;
+
                if(my == S)
                        my = import;
                if(my->name[0] == '.') {
-                       importdot(import);
+                       importdot(import, pack);
                        break;
                }
                if(my->name[0] == '_' && my->name[1] == '\0')
@@ -191,8 +198,7 @@ import_stmt:
                if(my->def && my->def->op == ONONAME)
                        my->def = N;
 
-               my->def = nod(OPACK, N, N);
-               my->def->sym = import;
+               my->def = pack;
                my->lastlineno = $1;
                import->block = 1;      // at top level
        }
@@ -209,7 +215,7 @@ import_here:
                $$ = parserline();
                pkgimportname = S;
                pkgmyname = S;
-               importfile(&$1);
+               importfile(&$1, $$);
        }
 |      sym LLITERAL
        {
@@ -219,14 +225,14 @@ import_here:
                pkgmyname = $1;
                if($1->def && ($1->name[0] != '_' || $1->name[1] != '\0'))
                        redeclare($1, "as imported package name");
-               importfile(&$2);
+               importfile(&$2, $$);
        }
 |      '.' LLITERAL
        {
                // import into my name space
                $$ = parserline();
                pkgmyname = lookup(".");
-               importfile(&$2);
+               importfile(&$2, $$);
        }
 
 import_package:
@@ -811,6 +817,7 @@ pexpr:
                if($1->op == OPACK) {
                        Sym *s;
                        s = restrictlookup($3->name, $1->sym->name);
+                       $1->used = 1;
                        $$ = oldname(s);
                        break;
                }
@@ -910,6 +917,8 @@ name:
        sym
        {
                $$ = oldname($1);
+               if($$->pack != N)
+                       $$->pack->used = 1;
        }
 
 labelname:
@@ -995,6 +1004,7 @@ dotname:
                if($1->op == OPACK) {
                        Sym *s;
                        s = restrictlookup($3->name, $1->sym->name);
+                       $1->used = 1;
                        $$ = oldname(s);
                        break;
                }
@@ -1245,6 +1255,14 @@ structdcl:
 
 packname:
        LNAME
+       {
+               Node *n;
+
+               $$ = $1;
+               n = oldname($1);
+               if(n->pack != N)
+                       n->pack->used = 1;
+       }
 |      LNAME '.' sym
        {
                char *pkg;
@@ -1252,8 +1270,10 @@ packname:
                if($1->def == N || $1->def->op != OPACK) {
                        yyerror("%S is not a package", $1);
                        pkg = $1->name;
-               } else
+               } else {
+                       $1->def->used = 1;
                        pkg = $1->def->sym->name;
+               }
                $$ = restrictlookup($3->name, pkg);
        }
 

diff --git a/src/cmd/gc/lex.c b/src/cmd/gc/lex.c
index fd78e446aaafe180392fc93e8e889b54d84492b6..05e71f87a36275d37ac7baed5de0ef9274b546b3 100644 (file)
--- a/src/cmd/gc/lex.c
+++ b/src/cmd/gc/lex.c
@@ -97,6 +97,7 @@ main(int argc, char *argv[])
                        Bterm(curio.bin);
        }
        testdclstack();
+       mkpackage(package);     // final import not used checks
        lexfini();
 
        typecheckok = 1;
@@ -259,13 +260,19 @@ findpkg(Strlit *name)
 }
 
 void
-importfile(Val *f)
+importfile(Val *f, int line)
 {
        Biobuf *imp;
        char *file, *p;
        int32 c;
        int len;
 
+       // Once we push the new file, we will not be able
+       // to print the current lineno correctly with %L.
+       // In case that line is the line of the import (likely),
+       // save the text for use in error messages.
+       importline = smprint("%L", line);
+
 // TODO: don't bother reloading imports more than once
 
        if(f->ctype != CTSTR) {
@@ -339,6 +346,7 @@ unimportfile(void)
                curio.bin = nil;
        } else
                lexlineno--;    // re correct sys.6 line number
+
        curio = pushedio;
        pushedio.bin = nil;
        inimportsys = 0;
@@ -1302,7 +1310,7 @@ lexinit(void)
        s->def = nod(ONONAME, N, N);
        s->def->iota = 1;
        s->def->sym = s;
-       
+
        s = pkglookup("true", "/builtin/");
        s->def = nodbool(1);
        s->def->sym = lookup("true");
@@ -1453,10 +1461,10 @@ mkpackage(char* pkg)
        int32 h;
        char *p;
 
-       if(strcmp(pkg, "_") == 0)
-               yyerror("invalid package name _");
-
        if(package == nopackage) {
+               if(strcmp(pkg, "_") == 0)
+                       yyerror("invalid package name _");
+
                // redefine all names to be this package.
                for(h=0; h<NHASH; h++)
                        for(s = hash[h]; s != S; s = s->link)
@@ -1476,12 +1484,21 @@ mkpackage(char* pkg)
                                        // TODO(rsc): remember that there was a package
                                        // name, so that the name cannot be redeclared
                                        // as a non-package in other files.
+                                       if(!s->def->used) {
+                                               print("%s: imported and not used: %s\n", s->def->pline, s->def->sym->name);
+                                               nerrors++;
+                                       }
                                        s->def = N;
                                        continue;
                                }
                                if(s->def->sym != s) {
                                        // throw away top-level name left over
                                        // from previous import . "x"
+                                       if(s->def->pack != N && !s->def->pack->used) {
+                                               print("%s: imported and not used: %s\n", s->def->pack->pline, s->def->pack->sym->name);
+                                               nerrors++;
+                                               s->def->pack->used = 1;
+                                       }
                                        s->def = N;
                                        continue;
                                }
@@ -1489,14 +1506,6 @@ mkpackage(char* pkg)
                }
        }
 
-/*
-       // declare this name as a package
-       s = lookup(package);
-       s->def = nod(OPACK, N, N);
-       s->def->sym = s;
-       s->block = -1;  // above top level
-*/
-
        if(outfile == nil) {
                p = strrchr(infile, '/');
                if(p == nil)

diff --git a/src/cmd/gc/subr.c b/src/cmd/gc/subr.c
index f2da5c003d52910ab1b2bf7d34054201ee18e5b6..27c13b02d1fe2bfa99522a98533c335a7b07ae2e 100644 (file)
--- a/src/cmd/gc/subr.c
+++ b/src/cmd/gc/subr.c
@@ -238,15 +238,16 @@ restrictlookup(char *name, char *pkg)
 // find all the exported symbols in package opkg
 // and make them available in the current package
 void
-importdot(Sym *opkg)
+importdot(Sym *opkg, Node *pack)
 {
        Sym *s, *s1;
        uint32 h;
-       int c;
+       int c, n;
 
        if(strcmp(opkg->name, package) == 0)
                return;
 
+       n = 0;
        c = opkg->name[0];
        for(h=0; h<NHASH; h++) {
                for(s = hash[h]; s != S; s = s->link) {
@@ -262,8 +263,15 @@ importdot(Sym *opkg)
                                continue;
                        }
                        s1->def = s->def;
+                       s1->def->pack = pack;
+                       n++;
                }
        }
+       if(n == 0) {
+               // can't possibly be used - there were no symbols
+               print("%L: imported and not used: %s\n", pack->pline, pack->sym->name);
+               nerrors++;
+       }
 }
 
 void