make Nim take roughly 100MB less RAM for bootstrapping via a new compiler switch -d:leanCompiler; useful for the Raberry PI

compiler/ccgexprs.nim

@@ -2030,6 +2030,9 @@ proc genMagicExpr(p: BProc, e: PNode, d: var TLoc, op: TMagic) =
     let n = lowerings.wrapProcForSpawn(p.module.g.graph, p.module.module, e, e.typ, nil, nil)
     expr(p, n, d)
   of mParallel:
+    when defined(leanCompiler):
+      quit "compiler built without support for the 'parallel' statement"
+    else:
       let n = semparallel.liftParallel(p.module.g.graph, p.module.module, e)
       expr(p, n, d)
   of mDeepCopy:

compiler/cgen.nim

@@ -14,7 +14,10 @@ import
   nversion, nimsets, msgs, std / sha1, bitsets, idents, types,
   ccgutils, os, ropes, math, passes, wordrecg, treetab, cgmeth,
   condsyms, rodutils, renderer, idgen, cgendata, ccgmerge, semfold, aliases,
-  lowerings, semparallel, tables, sets, ndi, lineinfos, pathutils, transf
+  lowerings, tables, sets, ndi, lineinfos, pathutils, transf
+
+when not defined(leanCompiler):
+  import semparallel
 
 import strutils except `%` # collides with ropes.`%`
 

compiler/main.nim

@@ -15,12 +15,15 @@ when not defined(nimcore):
 import
   llstream, strutils, ast, astalgo, lexer, syntaxes, renderer, options, msgs,
   os, condsyms, times,
-  wordrecg, sem, semdata, idents, passes, docgen, extccomp,
+  wordrecg, sem, semdata, idents, passes, extccomp,
-  cgen, jsgen, json, nversion,
+  cgen, json, nversion,
   platform, nimconf, importer, passaux, depends, vm, vmdef, types, idgen,
-  docgen2, parser, modules, ccgutils, sigmatch, ropes,
+  parser, modules, ccgutils, sigmatch, ropes,
   modulegraphs, tables, rod, lineinfos, pathutils
 
+when not defined(leanCompiler):
+  import jsgen, docgen, docgen2
+
 from magicsys import resetSysTypes
 
 proc codegenPass(g: ModuleGraph) =
@@ -57,6 +60,7 @@ proc commandCheck(graph: ModuleGraph) =
   semanticPasses(graph)  # use an empty backend for semantic checking only
   compileProject(graph)
 
+when not defined(leanCompiler):
   proc commandDoc2(graph: ModuleGraph; json: bool) =
     graph.config.errorMax = high(int)  # do not stop after first error
     semanticPasses(graph)
@@ -84,6 +88,7 @@ proc commandJsonScript(graph: ModuleGraph) =
   let proj = changeFileExt(graph.config.projectFull, "")
   extccomp.runJsonBuildInstructions(graph.config, proj)
 
+when not defined(leanCompiler):
   proc commandCompileToJS(graph: ModuleGraph) =
     #incl(gGlobalOptions, optSafeCode)
     setTarget(graph.config.target, osJS, cpuJS)
@@ -177,27 +182,45 @@ proc mainCommand*(graph: ModuleGraph) =
     else:
       rawMessage(conf, errGenerated, "'run' command not available; rebuild with -d:tinyc")
   of "js", "compiletojs":
+    when defined(leanCompiler):
+      quit "compiler wasn't built with JS code generator"
+    else:
       conf.cmd = cmdCompileToJS
       commandCompileToJS(graph)
   of "doc0":
+    when defined(leanCompiler):
+      quit "compiler wasn't built with documentation generator"
+    else:
       wantMainModule(conf)
       conf.cmd = cmdDoc
       loadConfigs(DocConfig, cache, conf)
       commandDoc(cache, conf)
   of "doc2", "doc":
+    when defined(leanCompiler):
+      quit "compiler wasn't built with documentation generator"
+    else:
       conf.cmd = cmdDoc
       loadConfigs(DocConfig, cache, conf)
       defineSymbol(conf.symbols, "nimdoc")
       commandDoc2(graph, false)
   of "rst2html":
+    when defined(leanCompiler):
+      quit "compiler wasn't built with documentation generator"
+    else:
       conf.cmd = cmdRst2html
       loadConfigs(DocConfig, cache, conf)
       commandRst2Html(cache, conf)
   of "rst2tex":
+    when defined(leanCompiler):
+      quit "compiler wasn't built with documentation generator"
+    else:
       conf.cmd = cmdRst2tex
       loadConfigs(DocTexConfig, cache, conf)
       commandRst2TeX(cache, conf)
   of "jsondoc0":
+    when defined(leanCompiler):
+      quit "compiler wasn't built with documentation generator"
+    else:
       wantMainModule(conf)
       conf.cmd = cmdDoc
       loadConfigs(DocConfig, cache, conf)
@@ -205,18 +228,27 @@ proc mainCommand*(graph: ModuleGraph) =
       defineSymbol(conf.symbols, "nimdoc")
       commandJson(cache, conf)
   of "jsondoc2", "jsondoc":
+    when defined(leanCompiler):
+      quit "compiler wasn't built with documentation generator"
+    else:
       conf.cmd = cmdDoc
       loadConfigs(DocConfig, cache, conf)
       wantMainModule(conf)
       defineSymbol(conf.symbols, "nimdoc")
       commandDoc2(graph, true)
   of "ctags":
+    when defined(leanCompiler):
+      quit "compiler wasn't built with documentation generator"
+    else:
       wantMainModule(conf)
       conf.cmd = cmdDoc
       loadConfigs(DocConfig, cache, conf)
       defineSymbol(conf.symbols, "nimdoc")
       commandTags(cache, conf)
   of "buildindex":
+    when defined(leanCompiler):
+      quit "compiler wasn't built with documentation generator"
+    else:
       conf.cmd = cmdDoc
       loadConfigs(DocConfig, cache, conf)
       commandBuildIndex(cache, conf)

compiler/sem.nim

@@ -16,13 +16,16 @@ import
   procfind, lookups, pragmas, passes, semdata, semtypinst, sigmatch,
   intsets, transf, vmdef, vm, idgen, aliases, cgmeth, lambdalifting,
   evaltempl, patterns, parampatterns, sempass2, linter, semmacrosanity,
-  semparallel, lowerings, pluginsupport, plugins/active, rod, lineinfos
+  lowerings, pluginsupport, plugins/active, rod, lineinfos
 
 from modulegraphs import ModuleGraph, PPassContext
 
 when defined(nimfix):
   import nimfix/prettybase
 
+when not defined(leanCompiler):
+  import semparallel
+
 # implementation
 
 proc semExpr(c: PContext, n: PNode, flags: TExprFlags = {}): PNode {.procvar.}

compiler/sempass2.nim

@@ -9,9 +9,12 @@
 
 import
   intsets, ast, astalgo, msgs, renderer, magicsys, types, idents, trees,
-  wordrecg, strutils, options, guards, writetracking, lineinfos, semfold,
+  wordrecg, strutils, options, guards, lineinfos, semfold,
   modulegraphs
 
+when not defined(leanCompiler):
+  import writetracking
+
 when defined(useDfa):
   import dfa
 

compiler/sigmatch.nim

@@ -15,7 +15,7 @@ import
   magicsys, condsyms, idents, lexer, options, parampatterns, strutils, trees,
   linter, lineinfos
 
-when defined(booting) or defined(nimsuggest):
+when (defined(booting) or defined(nimsuggest)) and not defined(leanCompiler):
   import docgen
 
 type

compiler/suggest.nim

@@ -115,7 +115,7 @@ proc symToSuggest(conf: ConfigRef; s: PSym, isLocal: bool, section: IdeCmd, info
       result.forth = typeToString(s.typ)
     else:
       result.forth = ""
-    when defined(nimsuggest) and not defined(noDocgen):
+    when defined(nimsuggest) and not defined(noDocgen) and not defined(leanCompiler):
       result.doc = s.extractDocComment
   let infox = if section in {ideUse, ideHighlight, ideOutline}: info else: s.info
   result.filePath = toFullPath(conf, infox)
@@ -153,7 +153,7 @@ proc `$`*(suggest: Suggest): string =
     result.add(sep)
     result.add($suggest.column)
     result.add(sep)
-    when defined(nimsuggest) and not defined(noDocgen):
+    when defined(nimsuggest) and not defined(noDocgen) and not defined(leanCompiler):
       result.add(suggest.doc.escape)
     if suggest.version == 0:
       result.add(sep)

koch.nim

@@ -51,6 +51,9 @@ Boot options:
   -d:release               produce a release version of the compiler
   -d:useLinenoise          use the linenoise library for interactive mode
                            (not needed on Windows)
+  -d:leanCompiler          produce a compiler without JS codegen or
+                           documentation generator in order to use less RAM
+                           for bootstrapping
 
 Commands for core developers:
   docs [options]           generates the full documentation