[src/trunk]: src/usr.bin/xlint/lint1 lint: fix function as controlling expres...

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

details:   https://anonhg.NetBSD.org/src/rev/579ffe27cd5e
branches:  trunk
changeset: 979723:579ffe27cd5e
user:      rillig <rillig%NetBSD.org@localhost>
date:      Fri Jan 08 02:11:45 2021 +0000

description:
lint: fix function as controlling expression (since 2020-12-31)

It's perfectly valid to directly use a function name as the controlling
expression of an if statement.  That function name is converted
implicitly to a pointer to that function, and that is a scalar value
then.

Spotted by christos in lib/libpthread/pthread.c:634.

diffstat:

 tests/usr.bin/xlint/lint1/d_fold_test.c   |   2 +-
 tests/usr.bin/xlint/lint1/d_fold_test.exp |   2 -
 tests/usr.bin/xlint/lint1/msg_204.c       |  69 ++++++++++++++++++++++++++++++-
 tests/usr.bin/xlint/lint1/msg_204.exp     |  16 ++++++-
 usr.bin/xlint/lint1/func.c                |   9 +--
 5 files changed, 86 insertions(+), 12 deletions(-)

diffs (157 lines):

diff -r beb8f9c0533e -r 579ffe27cd5e tests/usr.bin/xlint/lint1/d_fold_test.c
--- a/tests/usr.bin/xlint/lint1/d_fold_test.c   Fri Jan 08 01:40:03 2021 +0000
+++ b/tests/usr.bin/xlint/lint1/d_fold_test.c   Fri Jan 08 02:11:45 2021 +0000
@@ -58,7 +58,7 @@
 void if_array(struct arr arr)          { if (arr.arr) return; }
 void if_struct(struct s s)             { if (s) return; }
 void if_union(union u u)               { if (u) return; }
-void if_function(void (*f)(void))      { if (f) return; }
+void if_function(void)                 { if (if_function) return; }
 void if_pointer(void *p)               { if (p) return; }
 
 /* C99 6.8.5 */
diff -r beb8f9c0533e -r 579ffe27cd5e tests/usr.bin/xlint/lint1/d_fold_test.exp
--- a/tests/usr.bin/xlint/lint1/d_fold_test.exp Fri Jan 08 01:40:03 2021 +0000
+++ b/tests/usr.bin/xlint/lint1/d_fold_test.exp Fri Jan 08 02:11:45 2021 +0000
@@ -1,5 +1,3 @@
-d_fold_test.c(58): controlling expressions must have scalar type [204]
-d_fold_test.c(58): warning: argument arr unused in function if_array [231]
 d_fold_test.c(59): controlling expressions must have scalar type [204]
 d_fold_test.c(59): warning: argument s unused in function if_struct [231]
 d_fold_test.c(60): controlling expressions must have scalar type [204]
diff -r beb8f9c0533e -r 579ffe27cd5e tests/usr.bin/xlint/lint1/msg_204.c
--- a/tests/usr.bin/xlint/lint1/msg_204.c       Fri Jan 08 01:40:03 2021 +0000
+++ b/tests/usr.bin/xlint/lint1/msg_204.c       Fri Jan 08 02:11:45 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: msg_204.c,v 1.2 2021/01/08 01:40:03 rillig Exp $       */
+/*     $NetBSD: msg_204.c,v 1.3 2021/01/08 02:11:45 rillig Exp $       */
 # 3 "msg_204.c"
 
 // Test for message: controlling expressions must have scalar type [204]
@@ -32,3 +32,70 @@
        if (function_pointer)
                function_pointer();
 }
+
+struct s {
+       int member;
+};
+
+union u {
+       int member;
+};
+
+enum e {
+       E
+};
+
+struct arr {
+       int arr[4];
+};
+
+/* C99 6.2.5p2 */
+void if_Bool(_Bool b)                  { if (b) return; }
+
+/* C99 6.2.5p3 */
+void if_char(char c)                   { if (c) return; }
+
+/* C99 6.2.5p4 */
+void if_signed_char(signed char sc)    { if (sc) return; }
+void if_short_int(short s)             { if (s) return; }
+void if_int(int i)                     { if (i) return; }
+void if_long_int(long int l)           { if (l) return; }
+void if_long_long_int(long long int ll)        { if (ll) return; }
+
+/* C99 6.2.5p6 */
+void if_unsigned_char(unsigned char uc)                        { if (uc) return; }
+void if_unsigned_short_int(unsigned short us)          { if (us) return; }
+void if_unsigned_int(unsigned int ui)                  { if (ui) return; }
+void if_unsigned_long_int(unsigned long int ul)                { if (ul) return; }
+void if_unsigned_long_long_int(unsigned long long int ull) { if (ull) return; }
+
+/* C99 6.2.5p10 */
+void if_float(float f)                 { if (f) return; }
+void if_double(double d)               { if (d) return; }
+void if_long_double(long double ld)    { if (ld) return; }
+
+/* C99 6.2.5p11 */
+void if_float_Complex(float _Complex fc)               { if (fc) return; }
+void if_double_Complex(double _Complex dc)             { if (dc) return; }
+void if_long_double_Complex(long double _Complex ldc)  { if (ldc) return; }
+
+/* C99 6.2.5p16 */
+void if_enum(enum e e)                 { if (e) return; }
+
+/* C99 6.2.5p20 */
+void if_array(struct arr arr)          { if (arr.arr) return; }
+void if_struct(struct s s)             { if (s) return; }
+void if_union(union u u)               { if (u) return; }
+void if_function(void)                 { if (if_function) return; }
+void if_pointer(void *p)               { if (p) return; }
+
+/* C99 6.8.5 */
+void while_struct(struct s s)          { while (s) return; }
+void for_struct(struct s s)            { for (;s;) return; }
+void do_while_struct(struct s s)       { do { return; } while (s); }
+
+/*
+ * C99 6.5.15 for the '?:' operator does not explicitly mention that the
+ * controlling expression must have a scalar type, curiously.
+ */
+int conditional_struct(struct s s)     { return s ? 1 : 2; }
diff -r beb8f9c0533e -r 579ffe27cd5e tests/usr.bin/xlint/lint1/msg_204.exp
--- a/tests/usr.bin/xlint/lint1/msg_204.exp     Fri Jan 08 01:40:03 2021 +0000
+++ b/tests/usr.bin/xlint/lint1/msg_204.exp     Fri Jan 08 02:11:45 2021 +0000
@@ -1,2 +1,14 @@
-msg_204.c(19): controlling expressions must have scalar type [204]
-msg_204.c(28): controlling expressions must have scalar type [204]
+msg_204.c(87): controlling expressions must have scalar type [204]
+msg_204.c(87): warning: argument s unused in function if_struct [231]
+msg_204.c(88): controlling expressions must have scalar type [204]
+msg_204.c(88): warning: argument u unused in function if_union [231]
+msg_204.c(93): controlling expressions must have scalar type [204]
+msg_204.c(93): warning: argument s unused in function while_struct [231]
+msg_204.c(94): controlling expressions must have scalar type [204]
+msg_204.c(94): warning: end-of-loop code not reached [223]
+msg_204.c(94): warning: argument s unused in function for_struct [231]
+msg_204.c(95): controlling expressions must have scalar type [204]
+msg_204.c(95): warning: argument s unused in function do_while_struct [231]
+msg_204.c(101): first operand must have scalar type, op ? : [170]
+msg_204.c(101): warning: function conditional_struct expects to return value [214]
+msg_204.c(101): warning: argument s unused in function conditional_struct [231]
diff -r beb8f9c0533e -r 579ffe27cd5e usr.bin/xlint/lint1/func.c
--- a/usr.bin/xlint/lint1/func.c        Fri Jan 08 01:40:03 2021 +0000
+++ b/usr.bin/xlint/lint1/func.c        Fri Jan 08 02:11:45 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: func.c,v 1.52 2021/01/08 01:40:03 rillig Exp $ */
+/*     $NetBSD: func.c,v 1.53 2021/01/08 02:11:45 rillig Exp $ */
 
 /*
  * Copyright (c) 1994, 1995 Jochen Pohl
@@ -37,7 +37,7 @@
 
 #include <sys/cdefs.h>
 #if defined(__RCSID) && !defined(lint)
-__RCSID("$NetBSD: func.c,v 1.52 2021/01/08 01:40:03 rillig Exp $");
+__RCSID("$NetBSD: func.c,v 1.53 2021/01/08 02:11:45 rillig Exp $");
 #endif
 
 #include <stdlib.h>
@@ -537,16 +537,13 @@
 static tnode_t *
 check_controlling_expression(tnode_t *tn)
 {
-       // FIXME: dereference before null check
-       // FIXME: This is evaluated too early; see test msg_204
-       tspec_t t = tn->tn_type->t_tspec;
 
        if (tn != NULL)
                tn = cconv(tn);
        if (tn != NULL)
                tn = promote(NOOP, 0, tn);
 
-       if (tn != NULL && !tspec_is_scalar(t)) {
+       if (tn != NULL && !tspec_is_scalar(tn->tn_type->t_tspec)) {
                /* C99 6.5.15p4 for the ?: operator; see typeok:QUEST */
                /* C99 6.8.4.1p1 for if statements */
                /* C99 6.8.5p2 for while, do and for loops */