[src/trunk]: src/usr.bin/xlint/lint1 lint: add more details to message about ...

[rillig <rillig%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/99b756221c40
branches:  trunk
changeset: 369468:99b756221c40
user:      rillig <rillig%NetBSD.org@localhost>
date:      Fri Aug 19 19:40:39 2022 +0000

description:
lint: add more details to message about large bit-shifts

diffstat:

 tests/usr.bin/xlint/lint1/msg_267.c     |  55 +++++++++++++++++++++++++++++---
 tests/usr.bin/xlint/lint1/op_shl_lp64.c |   4 +-
 usr.bin/xlint/lint1/err.c               |   6 +-
 usr.bin/xlint/lint1/tree.c              |  12 +++---
 4 files changed, 60 insertions(+), 17 deletions(-)

diffs (172 lines):

diff -r 9627e420781c -r 99b756221c40 tests/usr.bin/xlint/lint1/msg_267.c
--- a/tests/usr.bin/xlint/lint1/msg_267.c       Fri Aug 19 19:13:04 2022 +0000
+++ b/tests/usr.bin/xlint/lint1/msg_267.c       Fri Aug 19 19:40:39 2022 +0000
@@ -1,19 +1,19 @@
-/*     $NetBSD: msg_267.c,v 1.5 2022/08/19 19:13:04 rillig Exp $       */
+/*     $NetBSD: msg_267.c,v 1.6 2022/08/19 19:40:39 rillig Exp $       */
 # 3 "msg_267.c"
 
-// Test for message: shift equal to size of object [267]
+// Test for message: shift amount %u equals bit-size of '%s' [267]
 
 int
 shr32(unsigned int x)
 {
-       /* expect+1: warning: shift equal to size of object [267] */
+       /* expect+1: warning: shift amount 32 equals bit-size of 'unsigned int' [267] */
        return x >> 32;
 }
 
 int
 shl32(unsigned int x)
 {
-       /* expect+1: warning: shift equal to size of object [267] */
+       /* expect+1: warning: shift amount 32 equals bit-size of 'unsigned int' [267] */
        return x << 32;
 }
 
@@ -26,7 +26,50 @@
 unsigned
 function(unsigned __attribute__((mode(TI))) arg)
 {
-       /* XXX: The 'size' usually means the size in bytes, not in bits. */
-       /* expect+1: warning: shift equal to size of object [267] */
+       /* expect+1: warning: shift amount 32 equals bit-size of 'unsigned int' [267] */
        return (arg >> 32) & 3;
 }
+
+unsigned
+shift_bit_field(void)
+{
+       struct {
+               unsigned bit_field:18;
+       } s = { 12345 };
+
+       /*
+        * A warning may be useful here for '>>' with a shift amount >= 18.
+        *
+        * For '<<' and bit-size <= 31, a warning only makes sense for shift
+        * amounts >= 31, as it is legitimate to rely on the default integer
+        * promotions of the left-hand operand. The default integer promotion
+        * turns the type into 'int', not 'unsigned int', therefore the 31.
+        * Using the same warning text would be confusing though.
+        *
+        * For '<<' and bit-size == 32, the standard case applies.
+        *
+        * As of 2022-08-19, Clang-tidy doesn't warn about any of these.
+        */
+       return
+           (s.bit_field >> 17) &
+           (s.bit_field >> 18) &
+           (s.bit_field >> 19) &
+           (s.bit_field >> 31) &
+           /* XXX: Why 'int:18', not 'unsigned int:18'? */
+           /* expect+1: warning: shift amount 32 equals bit-size of 'int:18' [267] */
+           (s.bit_field >> 32) &
+           /* XXX: Why 'int', not 'unsigned int:18'? */
+           /* expect+1: warning: shift amount 33 is greater than bit-size 32 of 'int' [122] */
+           (s.bit_field >> 33) &
+           (s.bit_field << 17) &
+           (s.bit_field << 18) &
+           (s.bit_field << 19) &
+           (s.bit_field << 31) &
+           /* XXX: Why 'int:18', not 'unsigned int:18'? */
+           /* expect+1: warning: shift amount 32 equals bit-size of 'int:18' [267] */
+           (s.bit_field << 32) &
+           /* XXX: Why 'int', not 'unsigned int:18'? */
+           /* expect+1: warning: shift amount 33 is greater than bit-size 32 of 'int' [122] */
+           (s.bit_field << 33) &
+           15;
+}
diff -r 9627e420781c -r 99b756221c40 tests/usr.bin/xlint/lint1/op_shl_lp64.c
--- a/tests/usr.bin/xlint/lint1/op_shl_lp64.c   Fri Aug 19 19:13:04 2022 +0000
+++ b/tests/usr.bin/xlint/lint1/op_shl_lp64.c   Fri Aug 19 19:40:39 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: op_shl_lp64.c,v 1.3 2021/08/21 11:50:57 rillig Exp $   */
+/*     $NetBSD: op_shl_lp64.c,v 1.4 2022/08/19 19:40:39 rillig Exp $   */
 # 3 "op_shl_lp64.c"
 
 /*
@@ -19,7 +19,7 @@
     - (((__uint128_t)1) << 9);
 
 const __uint128_t shl_128_129 =
-    /* expect+1: warning: shift equal to size of object [267] */
+    /* expect+1: warning: shift amount 128 equals bit-size of '__uint128_t' [267] */
     (((__uint128_t)1) << 128)
     /* expect+1: warning: shift amount 129 is greater than bit-size 128 of '__uint128_t' [122] */
     - (((__uint128_t)1) << 129);
diff -r 9627e420781c -r 99b756221c40 usr.bin/xlint/lint1/err.c
--- a/usr.bin/xlint/lint1/err.c Fri Aug 19 19:13:04 2022 +0000
+++ b/usr.bin/xlint/lint1/err.c Fri Aug 19 19:40:39 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: err.c,v 1.182 2022/07/16 22:36:06 rillig Exp $ */
+/*     $NetBSD: err.c,v 1.183 2022/08/19 19:40:39 rillig Exp $ */
 
 /*
  * Copyright (c) 1994, 1995 Jochen Pohl
@@ -37,7 +37,7 @@
 
 #include <sys/cdefs.h>
 #if defined(__RCSID)
-__RCSID("$NetBSD: err.c,v 1.182 2022/07/16 22:36:06 rillig Exp $");
+__RCSID("$NetBSD: err.c,v 1.183 2022/08/19 19:40:39 rillig Exp $");
 #endif
 
 #include <limits.h>
@@ -322,7 +322,7 @@
        "\\v undefined in traditional C",                             /* 264 */
        "%s does not support 'long long'",                            /* 265 */
        "'long double' is illegal in traditional C",                  /* 266 */
-       "shift equal to size of object",                              /* 267 */
+       "shift amount %u equals bit-size of '%s'",                    /* 267 */
        "variable '%s' declared inline",                              /* 268 */
        "argument '%s' declared inline",                              /* 269 */
        "function prototypes are illegal in traditional C",           /* 270 */
diff -r 9627e420781c -r 99b756221c40 usr.bin/xlint/lint1/tree.c
--- a/usr.bin/xlint/lint1/tree.c        Fri Aug 19 19:13:04 2022 +0000
+++ b/usr.bin/xlint/lint1/tree.c        Fri Aug 19 19:40:39 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: tree.c,v 1.475 2022/07/16 22:36:06 rillig Exp $        */
+/*     $NetBSD: tree.c,v 1.476 2022/08/19 19:40:39 rillig Exp $        */
 
 /*
  * Copyright (c) 1994, 1995 Jochen Pohl
@@ -37,7 +37,7 @@
 
 #include <sys/cdefs.h>
 #if defined(__RCSID)
-__RCSID("$NetBSD: tree.c,v 1.475 2022/07/16 22:36:06 rillig Exp $");
+__RCSID("$NetBSD: tree.c,v 1.476 2022/08/19 19:40:39 rillig Exp $");
 #endif
 
 #include <float.h>
@@ -1224,7 +1224,7 @@
 }
 
 static void
-typeok_shift(tspec_t lt, const tnode_t *rn, tspec_t rt)
+typeok_shift(const type_t *ltp, tspec_t lt, const tnode_t *rn, tspec_t rt)
 {
        if (rn->tn_op != CON)
                return;
@@ -1234,8 +1234,8 @@
                warning(121);
        } else if ((uint64_t)rn->tn_val->v_quad ==
                   (uint64_t)size_in_bits(lt)) {
-               /* shift equal to size of object */
-               warning(267);
+               /* shift amount %u equals bit-size of '%s' */
+               warning(267, (unsigned)rn->tn_val->v_quad, type_name(ltp));
        } else if ((uint64_t)rn->tn_val->v_quad > (uint64_t)size_in_bits(lt)) {
                /* shift amount %llu is greater than bit-size %llu of '%s' */
                warning(122, (unsigned long long)rn->tn_val->v_quad,
@@ -1457,7 +1457,7 @@
        case SHR:
                typeok_shr(mp, ln, lt, rn, rt);
        shift:
-               typeok_shift(lt, rn, rt);
+               typeok_shift(ltp, lt, rn, rt);
                break;
        case LT:
        case LE: