Inlay hints backport to Nim v1.6.x (#22920)

compiler/ast.nim

@@ -887,6 +887,7 @@ type
     info*: TLineInfo
     when defined(nimsuggest):
       endInfo*: TLineInfo
+      hasUserSpecifiedType*: bool  # used for determining whether to display inlay type hints
     owner*: PSym
     flags*: TSymFlags
     ast*: PNode               # syntax tree of proc, iterator, etc.:

compiler/modulegraphs.nim

@@ -53,6 +53,7 @@ type
   SymInfoPair* = object
     sym*: PSym
     info*: TLineInfo
+    isDecl*: bool
 
   ModuleGraph* {.acyclic.} = ref object
     ifaces*: seq[Iface]  ## indexed by int32 fileIdx

compiler/options.nim

@@ -185,7 +185,7 @@ type
   IdeCmd* = enum
     ideNone, ideSug, ideCon, ideDef, ideUse, ideDus, ideChk, ideChkFile, ideMod,
     ideHighlight, ideOutline, ideKnown, ideMsg, ideProject, ideGlobalSymbols,
-    ideRecompile, ideChanged, ideType, ideDeclaration, ideExpand
+    ideRecompile, ideChanged, ideType, ideDeclaration, ideExpand, ideInlayHints
 
   Feature* = enum  ## experimental features; DO NOT RENAME THESE!
     implicitDeref,
@@ -266,9 +266,24 @@ type
     version*: int
     endLine*: uint16
     endCol*: int
+    inlayHintInfo*: SuggestInlayHint
 
   Suggestions* = seq[Suggest]
 
+  SuggestInlayHintKind* = enum
+    sihkType = "Type",
+    sihkParameter = "Parameter"
+
+  SuggestInlayHint* = ref object
+    kind*: SuggestInlayHintKind
+    line*: int                   # Starts at 1
+    column*: int                 # Starts at 0
+    label*: string
+    paddingLeft*: bool
+    paddingRight*: bool
+    allowInsert*: bool
+    tooltip*: string
+
   ProfileInfo* = object
     time*: float
     count*: int
@@ -1035,6 +1050,7 @@ proc `$`*(c: IdeCmd): string =
   of ideRecompile: "recompile"
   of ideChanged: "changed"
   of ideType: "type"
+  of ideInlayHints: "inlayHints"
 
 proc floatInt64Align*(conf: ConfigRef): int16 =
   ## Returns either 4 or 8 depending on reasons.

compiler/semstmts.nim

@@ -569,9 +569,11 @@ proc semVarOrLet(c: PContext, n: PNode, symkind: TSymKind): PNode =
     if a.kind notin {nkIdentDefs, nkVarTuple}: illFormedAst(a, c.config)
     checkMinSonsLen(a, 3, c.config)
 
+    var hasUserSpecifiedType = false
     var typ: PType = nil
     if a[^2].kind != nkEmpty:
       typ = semTypeNode(c, a[^2], nil)
+      hasUserSpecifiedType = true
 
     var typFlags: TTypeAllowedFlags
 
@@ -644,6 +646,8 @@ proc semVarOrLet(c: PContext, n: PNode, symkind: TSymKind): PNode =
         addToVarSection(c, result, n, a)
         continue
       var v = semIdentDef(c, a[j], symkind, false)
+      when defined(nimsuggest):
+        v.hasUserSpecifiedType = hasUserSpecifiedType
       styleCheckDef(c, v)
       onDef(a[j].info, v)
       if sfGenSym notin v.flags:
@@ -724,9 +728,11 @@ proc semConst(c: PContext, n: PNode): PNode =
     if a.kind notin {nkConstDef, nkVarTuple}: illFormedAst(a, c.config)
     checkMinSonsLen(a, 3, c.config)
 
+    var hasUserSpecifiedType = false
     var typ: PType = nil
     if a[^2].kind != nkEmpty:
       typ = semTypeNode(c, a[^2], nil)
+      hasUserSpecifiedType = true
 
     var typFlags: TTypeAllowedFlags
 
@@ -771,6 +777,8 @@ proc semConst(c: PContext, n: PNode): PNode =
 
     for j in 0..<a.len-2:
       var v = semIdentDef(c, a[j], skConst)
+      when defined(nimsuggest):
+        v.hasUserSpecifiedType = hasUserSpecifiedType
       if sfGenSym notin v.flags: addInterfaceDecl(c, v)
       elif v.owner == nil: v.owner = getCurrOwner(c)
       styleCheckDef(c, v)

compiler/suggest.nim

@@ -103,7 +103,7 @@ proc getTokenLenFromSource(conf: ConfigRef; ident: string; info: TLineInfo): int
       result = 0
   elif ident[0] in linter.Letters and ident[^1] != '=':
     result = identLen(line, column)
-    if cmpIgnoreStyle(line[column..column + result - 1], ident) != 0:
+    if cmpIgnoreStyle(line[column..column + result - 1], ident[0..min(result-1,len(ident)-1)]) != 0:
       result = 0
   else:
     var sourceIdent: string
@@ -154,7 +154,10 @@ proc symToSuggest*(g: ModuleGraph; s: PSym, isLocal: bool, section: IdeCmd, info
       result.qualifiedPath.add(s.name.s)
 
     if s.typ != nil:
-      result.forth = typeToString(s.typ)
+      if section == ideInlayHints:
+        result.forth = typeToString(s.typ, preferInlayHint)
+      else:
+        result.forth = typeToString(s.typ)
     else:
       result.forth = ""
     when defined(nimsuggest) and not defined(noDocgen) and not defined(leanCompiler):
@@ -173,7 +176,7 @@ proc symToSuggest*(g: ModuleGraph; s: PSym, isLocal: bool, section: IdeCmd, info
     result.filePath = toFullPath(g.config, infox)
     result.line = toLinenumber(infox)
     result.column = toColumn(infox)
-    result.tokenLen = if section != ideHighlight:
+    result.tokenLen = if section notin {ideHighlight, ideInlayHints}:
                         s.name.s.len
                       else:
                         getTokenLenFromSource(g.config, s.name.s, infox)
@@ -181,50 +184,82 @@ proc symToSuggest*(g: ModuleGraph; s: PSym, isLocal: bool, section: IdeCmd, info
   result.endLine = endLine
   result.endCol = endCol
 
-proc `$`*(suggest: Suggest): string =
-  result = $suggest.section
+proc `$`*(suggest: SuggestInlayHint): string =
+  result = $suggest.kind
   result.add(sep)
-  if suggest.section == ideHighlight:
-    if suggest.symkind.TSymKind == skVar and suggest.isGlobal:
-      result.add("skGlobalVar")
-    elif suggest.symkind.TSymKind == skLet and suggest.isGlobal:
-      result.add("skGlobalLet")
+  result.add($suggest.line)
+  result.add(sep)
+  result.add($suggest.column)
+  result.add(sep)
+  result.add(suggest.label)
+  result.add(sep)
+  result.add($suggest.paddingLeft)
+  result.add(sep)
+  result.add($suggest.paddingRight)
+  result.add(sep)
+  result.add($suggest.allowInsert)
+  result.add(sep)
+  result.add(suggest.tooltip)
+
+proc `$`*(suggest: Suggest): string =
+  if suggest.section == ideInlayHints:
+    result = $suggest.inlayHintInfo
+  else:
+    result = $suggest.section
+    result.add(sep)
+    if suggest.section == ideHighlight:
+      if suggest.symkind.TSymKind == skVar and suggest.isGlobal:
+        result.add("skGlobalVar")
+      elif suggest.symkind.TSymKind == skLet and suggest.isGlobal:
+        result.add("skGlobalLet")
+      else:
+        result.add($suggest.symkind.TSymKind)
+      result.add(sep)
+      result.add($suggest.line)
+      result.add(sep)
+      result.add($suggest.column)
+      result.add(sep)
+      result.add($suggest.tokenLen)
     else:
       result.add($suggest.symkind.TSymKind)
-    result.add(sep)
-    result.add($suggest.line)
-    result.add(sep)
-    result.add($suggest.column)
-    result.add(sep)
-    result.add($suggest.tokenLen)
-  else:
-    result.add($suggest.symkind.TSymKind)
-    result.add(sep)
-    if suggest.qualifiedPath.len != 0:
-      result.add(suggest.qualifiedPath.join("."))
-    result.add(sep)
-    result.add(suggest.forth)
-    result.add(sep)
-    result.add(suggest.filePath)
-    result.add(sep)
-    result.add($suggest.line)
-    result.add(sep)
-    result.add($suggest.column)
-    result.add(sep)
-    when defined(nimsuggest) and not defined(noDocgen) and not defined(leanCompiler):
-      result.add(suggest.doc.escape)
-    if suggest.version in {0, 3}:
       result.add(sep)
-      result.add($suggest.quality)
-      if suggest.section == ideSug:
+      if suggest.qualifiedPath.len != 0:
+        result.add(suggest.qualifiedPath.join("."))
+      result.add(sep)
+      result.add(suggest.forth)
+      result.add(sep)
+      result.add(suggest.filePath)
+      result.add(sep)
+      result.add($suggest.line)
+      result.add(sep)
+      result.add($suggest.column)
+      result.add(sep)
+      when defined(nimsuggest) and not defined(noDocgen) and not defined(leanCompiler):
+        result.add(suggest.doc.escape)
+      if suggest.version in {0, 3}:
         result.add(sep)
-        result.add($suggest.prefix)
+        result.add($suggest.quality)
+        if suggest.section == ideSug:
+          result.add(sep)
+          result.add($suggest.prefix)
 
-  if (suggest.version == 3 and suggest.section in {ideOutline, ideExpand}):
-    result.add(sep)
-    result.add($suggest.endLine)
-    result.add(sep)
-    result.add($suggest.endCol)
+    if (suggest.version == 3 and suggest.section in {ideOutline, ideExpand}):
+      result.add(sep)
+      result.add($suggest.endLine)
+      result.add(sep)
+      result.add($suggest.endCol)
+
+proc suggestToSuggestInlayHint*(sug: Suggest): SuggestInlayHint =
+  SuggestInlayHint(
+    kind: sihkType,
+    line: sug.line,
+    column: sug.column + sug.tokenLen,
+    label: ": " & sug.forth,
+    paddingLeft: false,
+    paddingRight: false,
+    allowInsert: true,
+    tooltip: ""
+  )
 
 proc suggestResult*(conf: ConfigRef; s: Suggest) =
   if not isNil(conf.suggestionResultHook):
@@ -521,7 +556,7 @@ proc suggestSym*(g: ModuleGraph; info: TLineInfo; s: PSym; usageSym: var PSym; i
   ## misnamed: should be 'symDeclared'
   let conf = g.config
   when defined(nimsuggest):
-    g.suggestSymbols.mgetOrPut(info.fileIndex, @[]).add SymInfoPair(sym: s, info: info)
+    g.suggestSymbols.mgetOrPut(info.fileIndex, @[]).add SymInfoPair(sym: s, info: info, isDecl: isDecl)
 
     if conf.suggestVersion == 0:
       if s.allUsages.len == 0:

compiler/types.nim

@@ -25,6 +25,7 @@ type
     preferMixed,
       # most useful, shows: symbol + resolved symbols if it differs, e.g.:
       # tuple[a: MyInt{int}, b: float]
+    preferInlayHint,
 
   TTypeRelation* = enum      # order is important!
     isNone, isConvertible,
@@ -503,7 +504,7 @@ const
     "void", "iterable"]
 
 const preferToResolveSymbols = {preferName, preferTypeName, preferModuleInfo,
-  preferGenericArg, preferResolved, preferMixed}
+  preferGenericArg, preferResolved, preferMixed, preferInlayHint}
 
 template bindConcreteTypeToUserTypeClass*(tc, concrete: PType) =
   tc.add concrete
@@ -537,7 +538,10 @@ proc typeToString(typ: PType, prefer: TPreferedDesc = preferName): string =
     if prefer in preferToResolveSymbols and t.sym != nil and
          sfAnon notin t.sym.flags and t.kind != tySequence:
       if t.kind == tyInt and isIntLit(t):
-        result = t.sym.name.s & " literal(" & $t.n.intVal & ")"
+        if prefer == preferInlayHint:
+          result = t.sym.name.s
+        else:
+          result = t.sym.name.s & " literal(" & $t.n.intVal & ")"
       elif t.kind == tyAlias and t[0].kind != tyAlias:
         result = typeToString(t[0])
       elif prefer in {preferResolved, preferMixed}:
@@ -553,7 +557,7 @@ proc typeToString(typ: PType, prefer: TPreferedDesc = preferName): string =
           result = t.sym.name.s
         if prefer == preferMixed and result != t.sym.name.s:
           result = t.sym.name.s & "{" & result & "}"
-      elif prefer in {preferName, preferTypeName} or t.sym.owner.isNil:
+      elif prefer in {preferName, preferTypeName, preferInlayHint} or t.sym.owner.isNil:
         # note: should probably be: {preferName, preferTypeName, preferGenericArg}
         result = t.sym.name.s
         if t.kind == tyGenericParam and t.len > 0:
@@ -572,8 +576,11 @@ proc typeToString(typ: PType, prefer: TPreferedDesc = preferName): string =
       if not isIntLit(t) or prefer == preferExported:
         result = typeToStr[t.kind]
       else:
-        if prefer == preferGenericArg:
+        case prefer:
+        of preferGenericArg:
           result = $t.n.intVal
+        of preferInlayHint:
+          result = "int"
         else:
           result = "int literal(" & $t.n.intVal & ")"
     of tyGenericInst, tyGenericInvocation: