diagnostics: display suggested update after the caret-info

This commit adds the suggestion in green, on the line below the
caret-and-tildes.

    foo.y:1.1-14: warning: deprecated directive: '%error-verbose', use '%define parse.error verbose' [-Wdeprecated]
        1 | %error-verbose
          | ^~~~~~~~~~~~~~
          | %define parse.error verbose

The current approach, with location_caret_suggestion, is fragile:
there's a protocol of calls to the complain functions which is strict.
We should rather have a richer structure describing the diagnostics,
including with submessages such as the suggestions, passed in the end
to the routines in charge of formatting and printing them.

* src/location.h, src/location.c (location_caret_suggestion): New.
* src/complain.c (deprecated_directive): Use it.
* tests/diagnostics.at, tests/input.at: Adjust expectations.

data/bison-default.css

@@ -17,9 +17,14 @@
 /* This is an experimental feature.  The class names may change in the
    future.  */
 
+/* Diagnostics.  */
 .warning   { color: purple; }
 .error     { color: red; }
 .note      { color: cyan; }
+.insertion { color: green; }
+
 /* Semantic values in Bison's own parser traces.  */
 .value     { color: green; }
+
+/* "Sections" in traces (--trace).  */
 .trace0    { color: green; }

src/complain.c

@@ -546,17 +546,16 @@ bison_directive (location const *loc, char const *directive)
 void
 deprecated_directive (location const *loc, char const *old, char const *upd)
 {
-  if (feature_flag & feature_caret)
-    complain (loc, Wdeprecated,
-              _("deprecated directive, use %s"),
-              quote_n (1, upd));
-  else
-    complain (loc, Wdeprecated,
-              _("deprecated directive: %s, use %s"),
-              quote (old), quote_n (1, upd));
-  /* Register updates only if -Wdeprecated is enabled.  */
   if (warning_is_enabled (Wdeprecated))
-    fixits_register (loc, upd);
+    {
+      complain (loc, Wdeprecated,
+                _("deprecated directive: %s, use %s"),
+                quote (old), quote_n (1, upd));
+      if (feature_flag & feature_caret)
+        location_caret_suggestion (*loc, upd, stderr);
+      /* Register updates only if -Wdeprecated is enabled.  */
+      fixits_register (loc, upd);
+    }
 }
 
 void

src/location.c

@@ -470,6 +470,19 @@ location_caret (location loc, const char *style, FILE *out)
   }
 }
 
+void
+location_caret_suggestion (location loc, const char *s, FILE *out)
+{
+  const char *style = "insertion";
+  fprintf (out, "      | %*s",
+           loc.start.column - 1 - caret_info.skip + (caret_info.skip ? 3 : 0),
+           "");
+  begin_use_class (style, out);
+  fputs (s, out);
+  end_use_class (style, out);
+  putc ('\n', out);
+}
+
 bool
 location_empty (location loc)
 {

src/location.h

@@ -125,6 +125,10 @@ void caret_free (void);
    with the color STYLE.  */
 void location_caret (location loc, const char* style, FILE *out);
 
+/* Display a suggestion of replacement for LOC with S.  To call after
+   location_caret.  */
+void location_caret_suggestion (location loc, const char *s, FILE *out);
+
 /* Return -1, 0, 1, depending whether a is before, equal, or
    after b.  */
 static inline int

tests/diagnostics.at

@@ -318,6 +318,7 @@ input.y: <warning>warning:</warning> fix-its can be applied.  Rerun with option
 ## Screen width.  ##
 ## -------------- ##
 
+AT_TEST([[Screen width: 200 columns]],
 [[%token ABCDEFGHIJKLMNOPQRSTUVWXYZ  ABCDEFGHIJKLMNOPQRSTUVWXYZ  ABCDEFGHIJKLMNOPQRSTUVWXYZ  ABCDEFGHIJKLMNOPQRSTUVWXYZ
                                                        %error-verbose
 %%
@@ -340,11 +341,17 @@ input.y:9.92-117: <warning>warning:</warning> symbol ABCDEFGHIJKLMNOPQRSTUVWXYZ
     9 | %token ABCDEFGHIJKLMNOPQRSTUVWXYZ  ABCDEFGHIJKLMNOPQRSTUVWXYZ  ABCDEFGHIJKLMNOPQRSTUVWXYZ  <warning>ABCDEFGHIJKLMNOPQRSTUVWXYZ</warning>
       |                                                                                            <warning>^~~~~~~~~~~~~~~~~~~~~~~~~~</warning>
 input.y:9.8-33:       previous declaration
+    9 | %token <note>ABCDEFGHIJKLMNOPQRSTUVWXYZ</note>  ABCDEFGHIJKLMNOPQRSTUVWXYZ  ABCDEFGHIJKLMNOPQRSTUVWXYZ  ABCDEFGHIJKLMNOPQRSTUVWXYZ
+      |        <note>^~~~~~~~~~~~~~~~~~~~~~~~~~</note>
+input.y:10.56-69: <warning>warning:</warning> deprecated directive: '%error-verbose', use '%define parse.error verbose' [<warning>-Wdeprecated</warning>]
+   10 |                                                        <warning>%error-verbose</warning>
+      |                                                        <warning>^~~~~~~~~~~~~~</warning>
       |                                                        <insertion>%define parse.error verbose</insertion>
 input.y: <warning>warning:</warning> fix-its can be applied.  Rerun with option '--update'. [<warning>-Wother</warning>]
 ]],
 [[COLUMNS=200]])
 
+AT_TEST([[Screen width: 80 columns]],
 [[%token ABCDEFGHIJKLMNOPQRSTUVWXYZ  ABCDEFGHIJKLMNOPQRSTUVWXYZ  ABCDEFGHIJKLMNOPQRSTUVWXYZ  ABCDEFGHIJKLMNOPQRSTUVWXYZ
                                                        %error-verbose
 %%
@@ -367,11 +374,17 @@ input.y:9.92-117: <warning>warning:</warning> symbol ABCDEFGHIJKLMNOPQRSTUVWXYZ
     9 | ...TUVWXYZ  <warning>ABCDEFGHIJKLMNOPQRSTUVWXYZ</warning>
       |             <warning>^~~~~~~~~~~~~~~~~~~~~~~~~~</warning>
 input.y:9.8-33:       previous declaration
+    9 | %token <note>ABCDEFGHIJKLMNOPQRSTUVWXYZ</note>  ABCDEFGHIJKLMNOPQRSTUVWXYZ  ABCDEF...
+      |        <note>^~~~~~~~~~~~~~~~~~~~~~~~~~</note>
+input.y:10.56-69: <warning>warning:</warning> deprecated directive: '%error-verbose', use '%define parse.error verbose' [<warning>-Wdeprecated</warning>]
+   10 |                                                        <warning>%error-verbose</warning>
+      |                                                        <warning>^~~~~~~~~~~~~~</warning>
       |                                                        <insertion>%define parse.error verbose</insertion>
 input.y: <warning>warning:</warning> fix-its can be applied.  Rerun with option '--update'. [<warning>-Wother</warning>]
 ]],
 [[COLUMNS=80]])
 
+AT_TEST([[Screen width: 60 columns]],
 [[%token ABCDEFGHIJKLMNOPQRSTUVWXYZ  ABCDEFGHIJKLMNOPQRSTUVWXYZ  ABCDEFGHIJKLMNOPQRSTUVWXYZ  ABCDEFGHIJKLMNOPQRSTUVWXYZ
                                                        %error-verbose
 %%
@@ -394,6 +407,11 @@ input.y:9.92-117: <warning>warning:</warning> symbol ABCDEFGHIJKLMNOPQRSTUVWXYZ
     9 | ...TUVWXYZ  <warning>ABCDEFGHIJKLMNOPQRSTUVWXYZ</warning>
       |             <warning>^~~~~~~~~~~~~~~~~~~~~~~~~~</warning>
 input.y:9.8-33:       previous declaration
+    9 | %token <note>ABCDEFGHIJKLMNOPQRSTUVWXYZ</note>  ABCDEFGHIJKLMN...
+      |        <note>^~~~~~~~~~~~~~~~~~~~~~~~~~</note>
+input.y:10.56-69: <warning>warning:</warning> deprecated directive: '%error-verbose', use '%define parse.error verbose' [<warning>-Wdeprecated</warning>]
+   10 | ...         <warning>%error-verbose</warning>
+      |             <warning>^~~~~~~~~~~~~~</warning>
       |             <insertion>%define parse.error verbose</insertion>
 input.y: <warning>warning:</warning> fix-its can be applied.  Rerun with option '--update'. [<warning>-Wother</warning>]
 ]],
@@ -419,12 +437,14 @@ exp : '0'
 %%
 exp : '0'
 ]])
-
+
 AT_BISON_CHECK([[-fcaret -Wno-other input.y]], [0], [],
 [[input.y:2.1-12: warning: deprecated directive: '%pure-parser', use '%define api.pure' [-Wdeprecated]
-    2 | %pure-parser
+    2 | %pure-parser
+      | ^~~~~~~~~~~~
       | %define api.pure
 input.y:3.1-14: warning: deprecated directive: '%error-verbose', use '%define parse.error verbose' [-Wdeprecated]
+    3 | %error-verbose
       | ^~~~~~~~~~~~~~
       | %define parse.error verbose
 ]])

tests/input.at

@@ -2051,21 +2051,26 @@ AT_DATA([[input.y]],
 start: %empty;
 ]])
 AT_BISON_CHECK([[-fcaret input.y]], [1], [],
-[[input.y:1.1-26: warning: deprecated directive, use '%define api.push-pull both' [-Wdeprecated]
+[[input.y:1.1-26: warning: deprecated directive: '%define api.push_pull both', use '%define api.push-pull both' [-Wdeprecated]
     1 | %define api.push_pull both
       | ^~~~~~~~~~~~~~~~~~~~~~~~~~
-input.y:2.1-40: warning: deprecated directive, use '%define lr.keep-unreachable-state maybe' [-Wdeprecated]
+      | %define api.push-pull both
+input.y:2.1-40: warning: deprecated directive: '%define lr.keep_unreachable_states maybe', use '%define lr.keep-unreachable-state maybe' [-Wdeprecated]
     2 | %define lr.keep_unreachable_states maybe
       | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-input.y:3.1-23: warning: deprecated directive, use '%define api.namespace {foo}' [-Wdeprecated]
+      | %define lr.keep-unreachable-state maybe
+input.y:3.1-23: warning: deprecated directive: '%define namespace "foo"', use '%define api.namespace {foo}' [-Wdeprecated]
     3 | %define namespace "foo"
       | ^~~~~~~~~~~~~~~~~~~~~~~
-input.y:4.1-15: warning: deprecated directive, use '%define api.value.type variant' [-Wdeprecated]
+      | %define api.namespace {foo}
+input.y:4.1-15: warning: deprecated directive: '%define variant', use '%define api.value.type variant' [-Wdeprecated]
     4 | %define variant
       | ^~~~~~~~~~~~~~~
-input.y:5.1-34: warning: deprecated directive, use '%define api.parser.class {parser}' [-Wdeprecated]
+      | %define api.value.type variant
+input.y:5.1-34: warning: deprecated directive: '%define parser_class_name {parser}', use '%define api.parser.class {parser}' [-Wdeprecated]
     5 | %define parser_class_name {parser}
       | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+      | %define api.parser.class {parser}
 input.y:2.1-40: error: invalid value for %define Boolean variable 'lr.keep-unreachable-state'
     2 | %define lr.keep_unreachable_states maybe
       | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~