warnings: add [warning push] and [warning pop]

Add [warning push] and [warning pop] directives.

Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>

8 files changed, 124 insertions, 30 deletions

diff --git a/asm/directiv.c b/asm/directiv.c
index 943e532f..cd13938d 100644
--- a/asm/directiv.c
+++ b/asm/directiv.c
@@ -1,6 +1,6 @@
 /* ----------------------------------------------------------------------- *
  *
- *   Copyright 1996-2018 The NASM Authors - All Rights Reserved
+ *   Copyright 1996-2019 The NASM Authors - All Rights Reserved
  *   See the file AUTHORS included with the NASM distribution for
  *   the specific copyright holders.
  *
@@ -421,7 +421,14 @@ bool process_directives(char *directive)
         break;
     }
 
-    case D_WARNING:         /* [WARNING {+|-|*}warn-name] */
+    case D_WARNING:         /* [WARNING {push|pop|{+|-|*}warn-name}] */
+        value = nasm_skip_spaces(value);
+        if ((*value | 0x20) == 'p') {
+            if (!nasm_stricmp(value, "push"))
+                push_warnings();
+            else if (!nasm_stricmp(value, "pop"))
+                pop_warnings();
+        }
         set_warning_status(value);
         break;
 
diff --git a/asm/error.c b/asm/error.c
index ef3fd988..4e86a0d7 100644
--- a/asm/error.c
+++ b/asm/error.c
@@ -1,6 +1,6 @@
 /* ----------------------------------------------------------------------- *
  *
- *   Copyright 1996-2018 The NASM Authors - All Rights Reserved
+ *   Copyright 1996-2019 The NASM Authors - All Rights Reserved
  *   See the file AUTHORS included with the NASM distribution for
  *   the specific copyright holders.
  *
@@ -85,7 +85,7 @@ void nasm_warn(errflags severity, const char *fmt, ...)
 {
 	nasm_do_error(ERR_WARNING|severity);
 }
-    
+
 fatal_func nasm_panic_from_macro(const char *file, int line)
 {
 	nasm_panic("internal error at %s:%d\n", file, line);
@@ -96,6 +96,72 @@ fatal_func nasm_assert_failed(const char *file, int line, const char *msg)
 	nasm_panic("assertion %s failed at %s:%d", msg, file, line);
 }
 
+
+/*
+ * Warning stack management. Note that there is an implicit "push"
+ * after the command line has been parsed, but this particular push
+ * cannot be popped.
+ */
+struct warning_stack {
+	struct warning_stack *next;
+	uint8_t state[sizeof warning_state];
+};
+static struct warning_stack *warning_stack, *warning_state_init;
+
+/* Push the warning status onto the warning stack */
+void push_warnings(void)
+{
+	struct warning_stack *ws;
+
+	ws = nasm_malloc(sizeof *ws);
+	memcpy(ws->state, warning_state, sizeof warning_state);
+	ws->next = warning_stack;
+	warning_stack = ws;
+}
+
+/* Pop the warning status off the warning stack */
+void pop_warnings(void)
+{
+	struct warning_stack *ws = warning_stack;
+
+	memcpy(warning_state, ws->state, sizeof warning_state);
+	if (!ws->next) {
+		/*!
+		 *!warn-stack-empty [on] warning stack empty
+		 *!  a [WARNING POP] directive was executed when
+		 *!  the warning stack is empty. This is treated
+		 *!  as a [WARNING *all] directive.
+		 */
+		nasm_warn(WARN_WARN_STACK_EMPTY, "warning stack empty");
+	} else {
+		warning_stack = ws->next;
+		nasm_free(ws);
+	}
+}
+
+/* Call after the command line is parsed, but before the first pass */
+void init_warnings(void)
+{
+	push_warnings();
+	warning_state_init = warning_stack;
+}
+
+
+/* Call after each pass */
+void reset_warnings(void)
+{
+	struct warning_stack *ws = warning_stack;
+
+	/* Unwind the warning stack. We do NOT delete the last entry! */
+	while (ws->next) {
+		struct warning_stack *wst = ws;
+		ws = ws->next;
+		nasm_free(wst);
+	}
+	warning_stack = ws;
+	memcpy(warning_state, ws->state, sizeof warning_state);
+}
+
 /*
  * This is called when processing a -w or -W option, or a warning directive.
  * Returns on if if the action was successful.
@@ -120,6 +186,7 @@ bool set_warning_status(const char *value)
 	int i;
 
 	value = nasm_skip_spaces(value);
+
 	switch (*value) {
 	case '-':
 		action = WID_OFF;
@@ -185,7 +252,8 @@ bool set_warning_status(const char *value)
 				break;
 			case WID_RESET:
 				warning_state[i] &= ~mask;
-				warning_state[i] |= warning_state_init[i] & mask;
+				warning_state[i] |=
+					warning_state_init->state[i] & mask;
 				break;
 			}
 		}
@@ -199,6 +267,6 @@ bool set_warning_status(const char *value)
 		 */
 		nasm_warn(WARN_UNKNOWN_WARNING, "unknown warning name: %s", name);
 	}
-		
+
 	return ok;
 }
diff --git a/asm/nasm.c b/asm/nasm.c
index 6a0a8b00..283f45d3 100644
--- a/asm/nasm.c
+++ b/asm/nasm.c
@@ -511,7 +511,7 @@ int main(int argc, char **argv)
     }
 
     /* Save away the default state of warnings */
-    memcpy(warning_state_init, warning_state, sizeof warning_state_init);
+    init_warnings();
 
     /* Dependency filename if we are also doing other things */
     if (!depend_file && (operating_mode & ~OP_DEPEND)) {
@@ -550,6 +550,7 @@ int main(int argc, char **argv)
             while ((line = preproc->getline()))
                 nasm_free(line);
             preproc->cleanup_pass();
+            reset_warnings();
     } else if (operating_mode & OP_PREPROCESS) {
             char *line;
             const char *file_name = NULL;
@@ -568,9 +569,6 @@ int main(int argc, char **argv)
             _pass_type = PASS_FIRST; /* We emulate this assembly pass */
             preproc->reset(inname, PP_PREPROC, depend_list);
 
-            /* Revert all warnings to the default state */
-            memcpy(warning_state, warning_state_init, sizeof warning_state);
-
             while ((line = preproc->getline())) {
                 /*
                  * We generate %line directives if needed for later programs
@@ -592,6 +590,7 @@ int main(int argc, char **argv)
                 nasm_free(line);
             }
             preproc->cleanup_pass();
+            reset_warnings();
             if (ofile)
                 fclose(ofile);
             if (ofile && terminate_after_phase && !keep_all)
@@ -1334,8 +1333,7 @@ static void parse_cmdline(int argc, char **argv, int pass)
      * Initialize all the warnings to their default state, including
      * warning index 0 used for "always on".
      */
-    memcpy(warning_state,      warning_default, sizeof warning_state);
-    memcpy(warning_state_init, warning_default, sizeof warning_state_init);
+    memcpy(warning_state, warning_default, sizeof warning_state);
 
     /*
      * First, process the NASMENV environment variable.
@@ -1546,9 +1544,6 @@ static void assemble_file(const char *fname, struct strlist *depend_list)
         switch_segment(ofmt->section(NULL, &globalbits));
         preproc->reset(fname, PP_NORMAL, pass_final() ? depend_list : NULL);
 
-        /* Revert all warnings to the default state */
-        memcpy(warning_state, warning_state_init, sizeof warning_state);
-
         globallineno = 0;
 
         while ((line = preproc->getline())) {
@@ -1575,10 +1570,6 @@ static void assemble_file(const char *fname, struct strlist *depend_list)
 
         preproc->cleanup_pass();
 
-        /* Don't output further messages if we are dead anyway */
-        if (terminate_after_phase)
-            break;
-
         if (global_offset_changed) {
             switch (pass_type()) {
             case PASS_OPT:
@@ -1596,11 +1587,13 @@ static void assemble_file(const char *fname, struct strlist *depend_list)
                 if (stall_count > nasm_limit[LIMIT_STALLED] ||
                     pass_count() >= nasm_limit[LIMIT_PASSES]) {
                     /* No convergence, almost certainly dead */
-                    nasm_nonfatal("unable to find valid values for all labels "
-                                  "after %"PRId64" passes; "
-                                  "stalled for %"PRId64", giving up.",
-                                  pass_count(), stall_count);
-                    nasm_note("Possible causes: recursive EQUs, macro abuse.");
+                    nasm_nonfatalf(ERR_UNDEAD,
+                                   "unable to find valid values for all labels "
+                                   "after %"PRId64" passes; "
+                                   "stalled for %"PRId64", giving up.",
+                                   pass_count(), stall_count);
+                    nasm_notef(ERR_UNDEAD,
+                               "Possible causes: recursive EQUs, macro abuse.");
                 }
                 break;
 
@@ -1611,12 +1604,14 @@ static void assemble_file(const char *fname, struct strlist *depend_list)
                  *!  the second-to-last assembly pass. This is not
                  *!  inherently fatal, but may be a source of bugs.
                  */
-                nasm_warn(WARN_PHASE, "phase error during stabilization "
+                nasm_warn(WARN_PHASE|ERR_UNDEAD,
+                          "phase error during stabilization "
                           "pass, hoping for the best");
                 break;
 
             case PASS_FINAL:
-                nasm_nonfatal("phase error during code generation pass");
+                nasm_nonfatalf(ERR_UNDEAD,
+                               "phase error during code generation pass");
                 break;
 
             default:
@@ -1624,6 +1619,8 @@ static void assemble_file(const char *fname, struct strlist *depend_list)
                 break;
             }
         }
+
+        reset_warnings();
     }
 
     if (opt_verbose_info && pass_final()) {
diff --git a/asm/warnings.pl b/asm/warnings.pl
index cb336ada..0c2ed516 100755
--- a/asm/warnings.pl
+++ b/asm/warnings.pl
@@ -132,8 +132,6 @@ if ($what eq 'c') {
     print $out "\n};\n\n";
     printf $out "uint8_t warning_state[%d];\t/* Current state */\n",
 	$#warn_noall + 2;
-    printf $out "uint8_t warning_state_init[%d];\t/* Command-line state, for reset */\n",
-	$#warn_noall + 2;
 } elsif ($what eq 'h') {
     my $filename = basename($outfile);
     my $guard = $filename;
@@ -174,8 +172,6 @@ if ($what eq 'c') {
 	$#warn_noall + 2;
     printf $out "extern uint8_t warning_state[%d];\n",
 	$#warn_noall + 2;
-    printf $out "extern uint8_t warning_state_init[%d];\n",
-	$#warn_noall + 2;
     print $out "\n#endif /* $guard */\n";
 } elsif ($what eq 'doc') {
     my %whatdef = ( 'on' => 'Enabled',
diff --git a/doc/changes.src b/doc/changes.src
index a4df0473..ad539676 100644
--- a/doc/changes.src
+++ b/doc/changes.src
@@ -7,6 +7,12 @@
 The NASM 2 series supports x86-64, and is the production version of NASM
 since 2007.
 
+\S{cl-2.15} Version 2.15
+
+\b The state of warnings can now be saved and restored via the
+\c{[WARNING PUSH]} and \c{[WARNING POP]} directives. See
+\k{asmdir-warning}.
+
 \S{cl-2.14.03} Version 2.14.03
 
 \b Suppress nuisance "\c{label changed during code generation}" messages
diff --git a/doc/nasmdoc.src b/doc/nasmdoc.src
index 5ce113a2..a8559d46 100644
--- a/doc/nasmdoc.src
+++ b/doc/nasmdoc.src
@@ -4776,6 +4776,10 @@ more details about warning classes.
    the original value, either the default value or as specified on the
    command line.
 
+\b \c{[warning push]} saves the current warning state on a stack.
+
+\b \c{[warning pop]} restores the current warning state from the stack.
+
 The \c{[WARNING]} directive also accepts the \c{all}, \c{error} and
 \c{error=}\e{warning-class} specifiers.
 
diff --git a/include/error.h b/include/error.h
index 03380764..9091fe81 100644
--- a/include/error.h
+++ b/include/error.h
@@ -122,6 +122,12 @@ static inline vefunc nasm_set_verror(vefunc ve)
 /* Process a warning option or directive */
 bool set_warning_status(const char *value);
 
+/* Warning stack management */
+void push_warnings(void);
+void pop_warnings(void);
+void init_warnings(void);
+void reset_warnings(void);
+
 /* Should be included from within error.h only */
 #include "warnings.h"
 
diff --git a/test/warnstack.asm b/test/warnstack.asm
new file mode 100644
index 00000000..6e762904
--- /dev/null
+++ b/test/warnstack.asm
@@ -0,0 +1,10 @@
+%warning "Good warning"
+	[warning push]
+	[warning -user]
+%warning "Bad warning"
+	[warning pop]
+%warning "Good warning"
+	[warning -user]
+%warning "Bad warning"
+	[warning pop]		; should warn but reset all
+%warning "Good warning"