Merge remote-tracking branch 'remotes/armbru/tags/pull-qapi-2021-08-26' into staging

QAPI patches patches for 2021-08-26

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# gpg:                issuer "armbru@redhat.com"
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* remotes/armbru/tags/pull-qapi-2021-08-26:
  qapi: make 'if' condition strings simple identifiers
  qapi: add 'not' condition operation
  qapi: Use 'if': { 'any': ... } where appropriate
  qapi: add 'any' condition
  qapi: replace if condition list with dict {'all': [...]}
  qapidoc: introduce QAPISchemaIfCond.docgen()
  qapi: introduce QAPISchemaIfCond.cgen()
  qapi: add QAPISchemaIfCond.is_present()
  qapi: wrap Sequence[str] in an object
  docs: update the documentation upfront about schema configuration
  qapi: Fix crash on redefinition with a different condition

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

2 files changed, 30 insertions, 22 deletions

diff --git a/docs/devel/qapi-code-gen.rst b/docs/devel/qapi-code-gen.rst
index 26c62b0e7b..ced7a5ffe1 100644
--- a/docs/devel/qapi-code-gen.rst
+++ b/docs/devel/qapi-code-gen.rst
@@ -826,25 +826,31 @@ Configuring the schema
 Syntax::
 
     COND = STRING
-         | [ STRING, ... ]
+         | { 'all: [ COND, ... ] }
+         | { 'any: [ COND, ... ] }
+         | { 'not': COND }
 
 All definitions take an optional 'if' member.  Its value must be a
-string or a list of strings.  A string is shorthand for a list
-containing just that string.  The code generated for the definition
-will then be guarded by #if STRING for each STRING in the COND list.
+string, or an object with a single member 'all', 'any' or 'not'.
+
+The C code generated for the definition will then be guarded by an #if
+preprocessing directive with an operand generated from that condition:
+
+ * STRING will generate defined(STRING)
+ * { 'all': [COND, ...] } will generate (COND && ...)
+ * { 'any': [COND, ...] } will generate (COND || ...)
+ * { 'not': COND } will generate !COND
 
 Example: a conditional struct ::
 
  { 'struct': 'IfStruct', 'data': { 'foo': 'int' },
-   'if': ['defined(CONFIG_FOO)', 'defined(HAVE_BAR)'] }
+   'if': { 'all': [ 'CONFIG_FOO', 'HAVE_BAR' ] } }
 
 gets its generated code guarded like this::
 
- #if defined(CONFIG_FOO)
- #if defined(HAVE_BAR)
+ #if defined(CONFIG_FOO) && defined(HAVE_BAR)
  ... generated code ...
- #endif /* defined(HAVE_BAR) */
- #endif /* defined(CONFIG_FOO) */
+ #endif /* defined(HAVE_BAR) && defined(CONFIG_FOO) */
 
 Individual members of complex types, commands arguments, and
 event-specific data can also be made conditional.  This requires the
@@ -855,7 +861,7 @@ member 'bar' ::
 
  { 'struct': 'IfStruct', 'data':
    { 'foo': 'int',
-     'bar': { 'type': 'int', 'if': 'defined(IFCOND)'} } }
+     'bar': { 'type': 'int', 'if': 'IFCOND'} } }
 
 A union's discriminator may not be conditional.
 
@@ -867,7 +873,7 @@ value 'bar' ::
 
  { 'enum': 'IfEnum', 'data':
    [ 'foo',
-     { 'name' : 'bar', 'if': 'defined(IFCOND)' } ] }
+     { 'name' : 'bar', 'if': 'IFCOND' } ] }
 
 Likewise, features can be conditional.  This requires the longhand
 form of FEATURE_.
@@ -877,7 +883,7 @@ Example: a struct with conditional feature 'allow-negative-numbers' ::
  { 'struct': 'TestType',
    'data': { 'number': 'int' },
    'features': [ { 'name': 'allow-negative-numbers',
-                   'if': 'defined(IFCOND)' } ] }
+                   'if': 'IFCOND' } ] }
 
 Please note that you are responsible to ensure that the C code will
 compile with an arbitrary combination of conditions, since the
diff --git a/docs/sphinx/qapidoc.py b/docs/sphinx/qapidoc.py
index 87c67ab23f..d791b59492 100644
--- a/docs/sphinx/qapidoc.py
+++ b/docs/sphinx/qapidoc.py
@@ -112,17 +112,19 @@ class QAPISchemaGenRSTVisitor(QAPISchemaVisitor):
     def _nodes_for_ifcond(self, ifcond, with_if=True):
         """Return list of Text, literal nodes for the ifcond
 
-        Return a list which gives text like ' (If: cond1, cond2, cond3)', where
-        the conditions are in literal-text and the commas are not.
+        Return a list which gives text like ' (If: condition)'.
         If with_if is False, we don't return the "(If: " and ")".
         """
-        condlist = intersperse([nodes.literal('', c) for c in ifcond],
-                               nodes.Text(', '))
+
+        doc = ifcond.docgen()
+        if not doc:
+            return []
+        doc = nodes.literal('', doc)
         if not with_if:
-            return condlist
+            return [doc]
 
         nodelist = [nodes.Text(' ('), nodes.strong('', 'If: ')]
-        nodelist.extend(condlist)
+        nodelist.append(doc)
         nodelist.append(nodes.Text(')'))
         return nodelist
 
@@ -139,7 +141,7 @@ class QAPISchemaGenRSTVisitor(QAPISchemaVisitor):
             term.append(nodes.literal('', member.type.doc_type()))
         if member.optional:
             term.append(nodes.Text(' (optional)'))
-        if member.ifcond:
+        if member.ifcond.is_present():
             term.extend(self._nodes_for_ifcond(member.ifcond))
         return term
 
@@ -154,7 +156,7 @@ class QAPISchemaGenRSTVisitor(QAPISchemaVisitor):
                 nodes.literal('', variants.tag_member.name),
                 nodes.Text(' is '),
                 nodes.literal('', '"%s"' % variant.name)]
-        if variant.ifcond:
+        if variant.ifcond.is_present():
             term.extend(self._nodes_for_ifcond(variant.ifcond))
         return term
 
@@ -209,7 +211,7 @@ class QAPISchemaGenRSTVisitor(QAPISchemaVisitor):
         dlnode = nodes.definition_list()
         for section in doc.args.values():
             termtext = [nodes.literal('', section.member.name)]
-            if section.member.ifcond:
+            if section.member.ifcond.is_present():
                 termtext.extend(self._nodes_for_ifcond(section.member.ifcond))
             # TODO drop fallbacks when undocumented members are outlawed
             if section.text:
@@ -277,7 +279,7 @@ class QAPISchemaGenRSTVisitor(QAPISchemaVisitor):
     def _nodes_for_if_section(self, ifcond):
         """Return list of doctree nodes for the "If" section"""
         nodelist = []
-        if ifcond:
+        if ifcond.is_present():
             snode = self._make_section('If')
             snode += nodes.paragraph(
                 '', '', *self._nodes_for_ifcond(ifcond, with_if=False)