Add _Noreturn keyword (#44)

pull #44

Author: tgtakaoka

nregress/c99c11/noreturn/Stop.nc

@@ -0,0 +1,3 @@
+interface Stop {
+  command _Noreturn void stop_now(int i);
+}

nregress/c99c11/noreturn/StopM.nc

@@ -0,0 +1,11 @@
+#include <stdlib.h>
+#include <stdnoreturn.h>
+
+module StopM {
+  provides interface Stop;
+} implementation {
+  command noreturn void Stop.stop_now(int i) {
+    if (i > 0) exit(i);
+    // This causes "`noreturn' function doesn return'" compiler warning.
+  }
+}

nregress/c99c11/noreturn/TestP.nc

@@ -0,0 +1,17 @@
+#include <stdio.h>
+
+module TestP {
+  uses interface Stop;
+} implementation {
+  _Noreturn int warning_if_variable_has_noreturn;
+
+  int main() @C() @spontaneous() {
+    puts("Preparing to stop...");
+    warning_if_variable_has_noreturn = 0;
+    call Stop.stop_now(2);
+    // The following code will not been compiled and executed
+    // since not_stop_now() is declared as noreturn.
+    puts("This code is never executed.");
+    return 3;
+  }
+}

nregress/c99c11/noreturn/test.nc

@@ -0,0 +1,5 @@
+configuration test {
+} implementation {
+  components TestP, StopM;
+  TestP.Stop -> StopM;
+}

nregress/c99c11/run1

@@ -0,0 +1,18 @@
+keep=
+if [ -z "$NESC1" ]; then
+  NESC1=../../../src/nesc1
+  keep=1
+fi
+cd $1
+cfile=/tmp/c99c11.$$.c
+exe=/tmp/c99c11.out.$$
+$NESC1 -fnesc-separator=__ test.nc -o $cfile && \
+gcc -Wall -g -o $exe $cfile && \
+$exe
+ok=$?
+if [ -z "$keep" ]; then
+  rm -f $cfile $exe
+else
+  echo C file is $cfile, executable is $exe
+fi
+exit $ok

nregress/ok/c99c11.noreturn.1

@@ -0,0 +1 @@
+Preparing to stop...

nregress/ok/c99c11.noreturn.2

@@ -0,0 +1,10 @@
+In file included from test.nc:3:
+In component `TestP':
+TestP.nc:6: warning: variable `warning_if_variable_has_noreturn' declared `_Noreturn'
+TestP.nc:6:15: warning: variable ‘TestP__warning_if_variable_has_noreturn’ declared ‘_Noreturn’
+   _Noreturn int warning_if_variable_has_noreturn;
+               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~    
+StopM.nc: In function ‘StopM__Stop__stop_now’:
+StopM.nc:10:1: warning: ‘noreturn’ function does return
+   }
+ ^

nregress/ok/c99c11.noreturn.exit

@@ -0,0 +1 @@
+2

src/c-lex.h

@@ -66,6 +66,7 @@ enum rid
   RID_STATIC,
   RID_EXTERN,
   RID_REGISTER,
+  RID_NORETURN,
   RID_TYPEDEF,
   RID_COMMAND,
   RID_EVENT,

src/c-parse.gperf

@@ -50,6 +50,7 @@ __typeof__, TYPEOF, NORID
 __volatile, TYPE_QUAL, volatile_qualifier
 __volatile__, TYPE_QUAL, volatile_qualifier
 __builtin_va_arg, VA_ARG, NORID
+_Noreturn, SCSPEC, RID_NORETURN
 asm, ASM_KEYWORD, NORID
 auto, SCSPEC, RID_AUTO
 break, BREAK, NORID

src/c-parse.y

@@ -110,7 +110,7 @@ void yyerror();
 /* the reserved words */
 /* SCO include files test "ASM", so use something else. */
 %token <u.itoken> SIZEOF ENUM STRUCT UNION IF ELSE WHILE DO FOR SWITCH CASE DEFAULT
-%token <u.itoken> BREAK CONTINUE RETURN GOTO ASM_KEYWORD TYPEOF ALIGNOF
+%token <u.itoken> BREAK CONTINUE RETURN GOTO ASM_KEYWORD TYPEOF ALIGNOF NORETURN
 %token <u.itoken> ATTRIBUTE EXTENSION LABEL
 %token <u.itoken> REALPART IMAGPART VA_ARG OFFSETOF
 

src/semantics.c

@@ -594,27 +594,25 @@ scflags parse_scflags(int specbits)
     scf |= scf_async;
   if (specbits & 1 << RID_NORACE)
     scf |= scf_norace;
+  if (specbits & 1 << RID_NORETURN)
+    scf |= scf_noreturn;
 
   return scf;
 }
 
 void check_variable_scflags(scflags scf,
 			    location l, const char *kind, const char *name)
 {
-  const char *badqual = NULL;
-  void (*msg)(location l, const char *format, ...) = error_with_location;
+  static const char fmt_msg[] = "%s `%s' declared `%s'";
 
   /* default already covered in parse_declarator */
+  /* gcc just warns inline and _Noreturn for variable. */
   if (scf & scf_inline)
-    {
-      badqual = "inline";
-      msg = pedwarn_with_location; /* this is what gcc does */
-    }
+    pedwarn_with_location(l, fmt_msg, kind, name, "inline");
+  if (scf & scf_noreturn)
+    pedwarn_with_location(l, fmt_msg, kind, name, "_Noreturn");
   if (scf & scf_async)
-    badqual = "async";
-
-  if (badqual)
-    msg(l, "%s `%s' declared `%s'", kind, name, badqual);
+    error_with_location(l, fmt_msg, kind, name, "async");
 }
 
 void check_array_size(expression size, const char *printname)
@@ -3628,6 +3626,7 @@ static char *rid_name_int(int id)
     case RID_TASK: return "task";
     case RID_DEFAULT: return "default";
     case RID_NORACE: return "norace";
+    case RID_NORETURN: return "_Noreturn";
     default: assert(0); return NULL;
     }
 }

src/semantics.h

@@ -28,7 +28,8 @@ typedef enum {
   scf_inline = 1,
   scf_default = 2,
   scf_async = 4,
-  scf_norace = 8
+  scf_norace = 8,
+  scf_noreturn = 16
 } scflags;
 
 /* Predefined __builtin_va_list type */

src/unparse.c

@@ -631,7 +631,7 @@ static void prt_prefix(location loc, data_declaration ddecl,
 	    if (pinline)
 	      continue;
 	    break;
-	  case RID_REGISTER: case RID_TYPEDEF:
+	  case RID_REGISTER: case RID_TYPEDEF: case RID_NORETURN:
 	    break;
 	  }
 	set_location(r->location);