cmd/cc, runtime: disallow structs without tags

Structs without tags have no unique name to use in the
Go definitions generated from the C types.
This caused issue 8812, fixed by CL 149260043.
Avoid future problems by requiring struct tags.

Update runtime as needed.
(There is no other C code in the tree.)

LGTM=bradfitz, iant
R=golang-codereviews, bradfitz, dave, iant
CC=golang-codereviews, khr, r
https://golang.org/cl/150360043

src/cmd/cc/cc.y

@@ -1043,6 +1043,7 @@ complex:
 	}
 |	LSTRUCT sbody
 	{
+		diag(Z, "struct must have tag");
 		taggen++;
 		sprint(symb, "_%d_", taggen);
 		$$ = dotag(lookup(), TSTRUCT, autobn);

src/cmd/cc/y.tab.h

-/* A Bison parser, made by GNU Bison 2.7.12-4996.  */
+/* A Bison parser, made by GNU Bison 2.3.  */
 
-/* Bison interface for Yacc-like parsers in C
-   
-      Copyright (C) 1984, 1989-1990, 2000-2013 Free Software Foundation, Inc.
-   
-   This program is free software: you can redistribute it and/or modify
+/* Skeleton interface for Bison's Yacc-like parsers in C
+
+   Copyright (C) 1984, 1989, 1990, 2000, 2001, 2002, 2003, 2004, 2005, 2006
+   Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
-   the Free Software Foundation, either version 3 of the License, or
-   (at your option) any later version.
-   
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
-   
+
    You should have received a copy of the GNU General Public License
-   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor,
+   Boston, MA 02110-1301, USA.  */
 
 /* As a special exception, you may create a larger work that contains
    part or all of the Bison parser skeleton and distribute that work
@@ -26,20 +29,10 @@
    special exception, which will cause the skeleton and the resulting
    Bison output files to be licensed under the GNU General Public
    License without this special exception.
-   
+
    This special exception was added by the Free Software Foundation in
    version 2.2 of Bison.  */
 
-#ifndef YY_YY_Y_TAB_H_INCLUDED
-# define YY_YY_Y_TAB_H_INCLUDED
-/* Enabling traces.  */
-#ifndef YYDEBUG
-# define YYDEBUG 0
-#endif
-#if YYDEBUG
-extern int yydebug;
-#endif
-
 /* Tokens.  */
 #ifndef YYTOKENTYPE
 # define YYTOKENTYPE
@@ -196,12 +189,11 @@ extern int yydebug;
 
 
 
+
 #if ! defined YYSTYPE && ! defined YYSTYPE_IS_DECLARED
 typedef union YYSTYPE
-{
-/* Line 2053 of yacc.c  */
 #line 36 "cc.y"
-
+{
 	Node*	node;
 	Sym*	sym;
 	Type*	type;
@@ -225,30 +217,14 @@ typedef union YYSTYPE
 	int32	lval;
 	double	dval;
 	vlong	vval;
-
-
-/* Line 2053 of yacc.c  */
-#line 232 "y.tab.h"
-} YYSTYPE;
-# define YYSTYPE_IS_TRIVIAL 1
+}
+/* Line 1529 of yacc.c.  */
+#line 223 "y.tab.h"
+	YYSTYPE;
 # define yystype YYSTYPE /* obsolescent; will be withdrawn */
 # define YYSTYPE_IS_DECLARED 1
+# define YYSTYPE_IS_TRIVIAL 1
 #endif
 
 extern YYSTYPE yylval;
 
-#ifdef YYPARSE_PARAM
-#if defined __STDC__ || defined __cplusplus
-int yyparse (void *YYPARSE_PARAM);
-#else
-int yyparse ();
-#endif
-#else /* ! YYPARSE_PARAM */
-#if defined __STDC__ || defined __cplusplus
-int yyparse (void);
-#else
-int yyparse ();
-#endif
-#endif /* ! YYPARSE_PARAM */
-
-#endif /* !YY_YY_Y_TAB_H_INCLUDED  */

src/runtime/malloc.h

@@ -273,7 +273,8 @@ struct MStats
 	bool	debuggc;
 
 	// Statistics about allocation size classes.
-	struct {
+	
+	struct MStatsBySize {
 		uint32 size;
 		uint64 nmalloc;
 		uint64 nfree;
@@ -282,6 +283,7 @@ struct MStats
 	uint64	tinyallocs;	// number of tiny allocations that didn't cause actual allocation; not exported to Go directly
 };
 
+
 #define mstats runtime·memstats
 extern MStats mstats;
 void	runtime·updatememstats(GCStats *stats);
@@ -489,7 +491,7 @@ struct MHeap
 	// the padding makes sure that the MCentrals are
 	// spaced CacheLineSize bytes apart, so that each MCentral.lock
 	// gets its own cache line.
-	struct {
+	struct MHeapCentral {
 		MCentral mcentral;
 		byte pad[CacheLineSize];
 	} central[NumSizeClasses];

src/runtime/os_plan9.h

@@ -63,7 +63,7 @@ typedef struct Tos Tos;
 typedef intptr _Plink;
 
 struct Tos {
-	struct			/* Per process profiling */
+	struct TosProf			/* Per process profiling */
 	{
 		_Plink	*pp;	/* known to be 0(ptr) */
 		_Plink	*next;	/* known to be 4(ptr) */

src/runtime/proc.c

@@ -2421,7 +2421,7 @@ runtime·mcount(void)
 	return runtime·sched.mcount;
 }
 
-static struct {
+static struct ProfState {
 	uint32 lock;
 	int32 hz;
 } prof;

src/runtime/runtime.h

@@ -384,11 +384,11 @@ struct	M
 	// these are here because they are too large to be on the stack
 	// of low-level NOSPLIT functions.
 	LibCall	libcall;
-	struct {
+	struct MTs {
 		int64	tv_sec;
 		int64	tv_nsec;
 	} ts;
-	struct {
+	struct MScratch {
 		uintptr v[6];
 	} scratch;
 #endif

src/runtime/vdso_linux_amd64.c

@@ -52,7 +52,7 @@ typedef uint16 Elf64_Section;
 typedef Elf64_Half Elf64_Versym;
 
 
-typedef struct
+typedef struct Elf64_Sym
 {
 	Elf64_Word st_name;
 	byte st_info;
@@ -62,7 +62,7 @@ typedef struct
 	Elf64_Xword st_size;
 } Elf64_Sym;
 
-typedef struct
+typedef struct Elf64_Verdef
 {
 	Elf64_Half vd_version; /* Version revision */
 	Elf64_Half vd_flags;   /* Version information */
@@ -73,7 +73,7 @@ typedef struct
 	Elf64_Word vd_next;    /* Offset in bytes to next verdef entry */
 } Elf64_Verdef;
 
-typedef struct
+typedef struct Elf64_Ehdr
 {
 	byte e_ident[EI_NIDENT]; /* Magic number and other info */
 	Elf64_Half e_type;       /* Object file type */
@@ -91,7 +91,7 @@ typedef struct
 	Elf64_Half e_shstrndx;   /* Section header string table index */
 } Elf64_Ehdr;
 
-typedef struct
+typedef struct Elf64_Phdr
 {
 	Elf64_Word p_type;    /* Segment type */
 	Elf64_Word p_flags;   /* Segment flags */
@@ -103,7 +103,7 @@ typedef struct
 	Elf64_Xword p_align;  /* Segment alignment */
 } Elf64_Phdr;
 
-typedef struct
+typedef struct Elf64_Shdr
 {
 	Elf64_Word sh_name;       /* Section name (string tbl index) */
 	Elf64_Word sh_type;       /* Section type */
@@ -117,7 +117,7 @@ typedef struct
 	Elf64_Xword sh_entsize;   /* Entry size if section holds table */
 } Elf64_Shdr;
 
-typedef struct
+typedef struct Elf64_Dyn
 {
 	Elf64_Sxword d_tag; /* Dynamic entry type */
 	union
@@ -127,13 +127,13 @@ typedef struct
 	} d_un;
 } Elf64_Dyn;
 
-typedef struct
+typedef struct Elf64_Verdaux
 {
 	Elf64_Word vda_name; /* Version or dependency names */
 	Elf64_Word vda_next; /* Offset in bytes to next verdaux entry */
 } Elf64_Verdaux;
 
-typedef struct
+typedef struct Elf64_auxv_t
 {
 	uint64 a_type;        /* Entry type */
 	union
@@ -143,13 +143,13 @@ typedef struct
 } Elf64_auxv_t;
 
 
-typedef struct {
+typedef struct symbol_key {
 	byte* name;
 	int32 sym_hash;
 	void** var_ptr;
 } symbol_key;
 
-typedef struct {
+typedef struct version_key {
 	byte* version;
 	int32 ver_hash;
 } version_key;