allow setting template/macro recursive evaluation limits (#7652)

* allow setting template/macro recursive evaluation limits

* revert setting template/macro eval limits
set them to 1000

compiler/commands.nim

@@ -702,7 +702,6 @@ proc processSwitch(switch, arg: string, pass: TCmdLinePass, info: TLineInfo;
     expectNoArg(switch, arg, pass, info)
     useNimNamespace = true
     defineSymbol("cppCompileToNamespace")
-    
   else:
     if strutils.find(switch, '.') >= 0: options.setConfigVar(switch, arg)
     else: invalidCmdLineOption(pass, switch, info)

compiler/evaltempl.nim

@@ -106,8 +106,9 @@ proc evalTemplateArgs(n: PNode, s: PSym; fromHlo: bool): PNode =
   for i in 1 .. genericParams:
     result.addSon n.sons[givenRegularParams + i]
 
+# to prevent endless recursion in template instantiation
+const evalTemplateLimit* = 1000
 var evalTemplateCounter* = 0
-  # to prevent endless recursion in templates instantiation
 
 proc wrapInComesFrom*(info: TLineInfo; sym: PSym; res: PNode): PNode =
   when true:
@@ -133,7 +134,7 @@ proc wrapInComesFrom*(info: TLineInfo; sym: PSym; res: PNode): PNode =
 
 proc evalTemplate*(n: PNode, tmpl, genSymOwner: PSym; fromHlo=false): PNode =
   inc(evalTemplateCounter)
-  if evalTemplateCounter > 100:
+  if evalTemplateCounter > evalTemplateLimit:
     globalError(n.info, errTemplateInstantiationTooNested)
     result = n
 

compiler/hlo.nim

@@ -44,7 +44,7 @@ proc applyPatterns(c: PContext, n: PNode): PNode =
         assert x.kind in {nkStmtList, nkCall}
         # better be safe than sorry, so check evalTemplateCounter too:
         inc(evalTemplateCounter)
-        if evalTemplateCounter > 100:
+        if evalTemplateCounter > evalTemplateLimit:
           globalError(n.info, errTemplateInstantiationTooNested)
         # deactivate this pattern:
         c.patterns[i] = nil

compiler/msgs.nim

@@ -87,7 +87,8 @@ type
     errNoReturnTypeDeclared,
     errNoCommand, errInvalidCommandX, errXOnlyAtModuleScope,
     errXNeedsParamObjectType,
-    errTemplateInstantiationTooNested, errInstantiationFrom,
+    errTemplateInstantiationTooNested, errMacroInstantiationTooNested,
+    errInstantiationFrom,
     errInvalidIndexValueForTuple, errCommandExpectsFilename,
     errMainModuleMustBeSpecified,
     errXExpected,
@@ -329,7 +330,8 @@ const
     errInvalidCommandX: "invalid command: \'$1\'",
     errXOnlyAtModuleScope: "\'$1\' is only allowed at top level",
     errXNeedsParamObjectType: "'$1' needs a parameter that has an object type",
-    errTemplateInstantiationTooNested: "template/macro instantiation too nested",
+    errTemplateInstantiationTooNested: "template instantiation too nested, try --evalTemplateLimit:N",
+    errMacroInstantiationTooNested: "macro instantiation too nested, try --evalMacroLimit:N",
     errInstantiationFrom: "template/generic instantiation from here",
     errInvalidIndexValueForTuple: "invalid index value for tuple subscript",
     errCommandExpectsFilename: "command expects a filename argument",

compiler/sem.nim

@@ -377,7 +377,7 @@ proc semAfterMacroCall(c: PContext, call, macroResult: PNode,
   ## reassigned, and binding the unbound identifiers that the macro output
   ## contains.
   inc(evalTemplateCounter)
-  if evalTemplateCounter > 100:
+  if evalTemplateCounter > evalTemplateLimit:
     globalError(s.info, errTemplateInstantiationTooNested)
   c.friendModules.add(s.owner.getModule)
 

compiler/vm.nim

@@ -1729,14 +1729,16 @@ iterator genericParamsInMacroCall*(macroSym: PSym, call: PNode): (PSym, PNode) =
     let posInCall = macroSym.typ.len + i
     yield (genericParam, call[posInCall])
 
+# to prevent endless recursion in macro instantiation
+const evalMacroLimit = 1000
 var evalMacroCounter: int
 
 proc evalMacroCall*(module: PSym; cache: IdentCache, n, nOrig: PNode,
                     sym: PSym): PNode =
   # XXX globalError() is ugly here, but I don't know a better solution for now
   inc(evalMacroCounter)
-  if evalMacroCounter > 100:
+  if evalMacroCounter > evalMacroLimit:
-    globalError(n.info, errTemplateInstantiationTooNested)
+    globalError(n.info, errMacroInstantiationTooNested)
 
   # immediate macros can bypass any type and arity checking so we check the
   # arity here too:

doc/advopt.txt

@@ -76,7 +76,7 @@ Advanced options:
   --NimblePath:PATH         add a path for Nimble support
   --noNimblePath            deactivate the Nimble path
   --noCppExceptions         use default exception handling with C++ backend
-  --cppCompileToNamespace   use namespace "Nim" for the generated C++ code 
+  --cppCompileToNamespace   use namespace "Nim" for the generated C++ code
   --excludePath:PATH        exclude a path from the list of search paths
   --dynlibOverride:SYMBOL   marks SYMBOL so that dynlib:SYMBOL
                             has no effect and can be statically linked instead;