[committed] c: Less warnings for parameters declared as arrays [PR98536]

[committed] c: Less warnings for parameters declared as arrays [PR98536]

[Martin Uecker]

I splitted up the patch into two parts and committed only
the FE parts which were already approved and the tests.
This solves one of the two issues.

Bootstrapped and regression tested on x86_64-pc-linux-gnu.


    Less warnings for parameters declared as arrays [PR98536]
    
    To avoid false positivies, tune the warnings for parameters declared
    as arrays with size expressions.  Do not warn when more bounds are
    specified in the declaration than before.
    
            PR c/98536
    
            c-family/
            * c-warn.cc (warn_parm_array_mismatch): Do not warn if more
            bounds are specified.
    
            gcc/testsuite:
            * gcc.dg/Wvla-parameter-4.c: Adapt test.
            * gcc.dg/attr-access-2.c: Adapt test.


diff --git a/gcc/c-family/c-warn.cc b/gcc/c-family/c-warn.cc
index d4d62c48b20..b7c5d7c01a2 100644
--- a/gcc/c-family/c-warn.cc
+++ b/gcc/c-family/c-warn.cc
@@ -3599,23 +3599,13 @@ warn_parm_array_mismatch (location_t origloc, tree fndecl, tree newparms)
 	      continue;
 	    }
 
-	  if (newunspec != curunspec)
+	  if (newunspec > curunspec)
 	    {
 	      location_t warnloc = newloc, noteloc = origloc;
 	      const char *warnparmstr = newparmstr.c_str ();
 	      const char *noteparmstr = curparmstr.c_str ();
 	      unsigned warnunspec = newunspec, noteunspec = curunspec;
 
-	      if (newunspec < curunspec)
-		{
-		  /* If the new declaration has fewer unspecified bounds
-		     point the warning to the previous declaration to make
-		     it clear that that's the one to change.  Otherwise,
-		     point it to the new decl.  */
-		  std::swap (warnloc, noteloc);
-		  std::swap (warnparmstr, noteparmstr);
-		  std::swap (warnunspec, noteunspec);
-		}
 	      if (warning_n (warnloc, OPT_Wvla_parameter, warnunspec,
 			     "argument %u of type %s declared with "
 			     "%u unspecified variable bound",
@@ -3643,14 +3633,10 @@ warn_parm_array_mismatch (location_t origloc, tree fndecl, tree newparms)
 	}
 
       /* Iterate over the lists of VLA variable bounds, comparing each
-	 pair for equality, and diagnosing mismatches.  The case of
-	 the lists having different lengths is handled above so at
-	 this point they do .  */
-      for (tree newvbl = newa->size, curvbl = cura->size; newvbl;
+	 pair for equality, and diagnosing mismatches.  */
+      for (tree newvbl = newa->size, curvbl = cura->size; newvbl && curvbl;
 	   newvbl = TREE_CHAIN (newvbl), curvbl = TREE_CHAIN (curvbl))
 	{
-	  gcc_assert (curvbl);
-
 	  tree newpos = TREE_PURPOSE (newvbl);
 	  tree curpos = TREE_PURPOSE (curvbl);
 
diff --git a/gcc/testsuite/gcc.dg/Wvla-parameter-4.c b/gcc/testsuite/gcc.dg/Wvla-parameter-4.c
index 599ad19a3e4..f35faea361a 100644
--- a/gcc/testsuite/gcc.dg/Wvla-parameter-4.c
+++ b/gcc/testsuite/gcc.dg/Wvla-parameter-4.c
@@ -12,11 +12,6 @@ typedef int IA3[3];
 /* Verify the warning points to the declaration with more unspecified
    bounds, guiding the user to specify them rather than making them all
    unspecified.  */
-void* f_pIA3ax (IA3 *x[*]);             // { dg-warning "argument 1 of type 'int \\\(\\\*\\\[\\\*]\\\)\\\[3]' .aka '\[^\n\r\}\]+'. declared with 1 unspecified variable bound" }
-void* f_pIA3ax (IA3 *x[*]);
-void* f_pIA3ax (IA3 *x[n]);             // { dg-message "subsequently declared as 'int \\\(\\\*\\\[n]\\\)\\\[3]' with 0 unspecified variable bounds" "note" }
-void* f_pIA3ax (IA3 *x[n]) { return x; }
-
 
 void* f_pIA3an (IA3 *x[n]);              // { dg-message "previously declared as 'int \\\(\\\*\\\[n]\\\)\\\[3]' with 0 unspecified variable bounds" "note" }
 void* f_pIA3an (IA3 *x[n]);
diff --git a/gcc/testsuite/gcc.dg/attr-access-2.c b/gcc/testsuite/gcc.dg/attr-access-2.c
index 76baddffc9f..616b7a9527c 100644
--- a/gcc/testsuite/gcc.dg/attr-access-2.c
+++ b/gcc/testsuite/gcc.dg/attr-access-2.c
@@ -60,16 +60,6 @@ RW (2, 1) void f10 (int n, char a[n])   // { dg-warning "attribute 'access *\\\(
                                         // { dg-warning "argument 2 of type 'char\\\[n]' declared as a variable length array"  "" { target *-*-* } .-1 }
 { (void)&n; (void)&a; }
 
-
-/* The following is diagnosed to point out declarations with the T[*]
-   form in headers where specifying the bound is just as important as
-   in the definition (to detect bugs).  */
-          void f11 (int, char[*]);      // { dg-warning "argument 2 of type 'char\\\[\\\*\\\]' declared with 1 unspecified variable bound" }
-          void f11 (int m, char a[m]);  // { dg-message "subsequently declared as 'char\\\[m]' with 0 unspecified variable bounds" "note" }
-RW (2, 1) void f11 (int n, char arr[n]) // { dg-message "subsequently declared as 'char\\\[n]' with 0 unspecified variable bounds" "note" }
-{ (void)&n; (void)&arr; }
-
-
 /* Verify that redeclaring a function with attribute access applying
    to an array parameter of any form is not diagnosed.  */
           void f12__ (int, int[]) RW (2, 1);