From 149ce8364e004cd2bb56f3ecb0a822b9d507e83c Mon Sep 17 00:00:00 2001
From: quantimnot <quantimnot@users.noreply.github.com>
Date: Thu, 25 Aug 2022 08:31:55 -0400
Subject: [PATCH] Add check of consistent foreign symbol usage [skip ci]

Checking the style of foreign symbol usages was completely disabled by
PR #19822. Now all style checks of a foreign symbol are checked against
the first time the symbol is used within a module.
---
 compiler/linter.nim        | 23 ++++++++++++++++++-----
 compiler/semdata.nim       |  1 +
 tests/stylecheck/thint.nim |  5 +++++
 3 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/compiler/linter.nim b/compiler/linter.nim
index 122e2544bd519..4ac0dd7b33900 100644
--- a/compiler/linter.nim
+++ b/compiler/linter.nim
@@ -9,7 +9,7 @@
 
 ## This module implements the style checker.
 
-import std/strutils
+import std/[strutils, tables]
 from std/sugar import dup
 
 import options, ast, msgs, idents, lineinfos, wordrecg, astmsgs, semdata, packages
@@ -113,7 +113,7 @@ template styleCheckDef*(ctx: PContext; s: PSym) =
   ## Check symbol definitions adhere to NEP1 style rules.
   styleCheckDef(ctx, s.info, s, s.kind)
 
-proc differs(conf: ConfigRef; info: TLineInfo; newName: string): string =
+proc extractIdent(conf: ConfigRef; info: TLineInfo): tuple[source: string, first, last: int] =
   let line = sourceLine(conf, info)
   var first = min(info.col.int, line.len)
   if first < 0: return
@@ -121,8 +121,11 @@ proc differs(conf: ConfigRef; info: TLineInfo; newName: string): string =
   while first > 0 and line[first-1] in Letters: dec first
   if first < 0: return
   if first+1 < line.len and line[first] == '`': inc first
-
   let last = first+identLen(line, first)-1
+  (line, first, last)
+
+proc differs(conf: ConfigRef; info: TLineInfo; newName: string): string =
+  let (line, first, last) = conf.extractIdent(info)
   result = differ(line, first, last, newName)
 
 proc styleCheckUseImpl(conf: ConfigRef; info: TLineInfo; s: PSym) =
@@ -131,15 +134,25 @@ proc styleCheckUseImpl(conf: ConfigRef; info: TLineInfo; s: PSym) =
   if badName.len > 0:
     lintReport(conf, info, newName, badName, "".dup(addDeclaredLoc(conf, s)))
 
+proc styleCheckUsagesMatchFirstUse(ctx: PContext; info: TLineInfo; sym: PSym) =
+  let (line, first, last) = ctx.config.extractIdent(info)
+  discard ctx.firstUsageOfForeignSym.hasKeyOrPut(sym.id, (line[first..last], info))
+  let (firstUseIdent, firstUseLineInfo) = ctx.firstUsageOfForeignSym[sym.id]
+  let badName = differ(line, first, last, firstUseIdent)
+  if badName.len > 0:
+    lintReport(ctx.config, info, firstUseIdent, badName, " [first used at $1]" % [toFileLineCol(ctx.config, firstUseLineInfo)])
+
 template styleCheckUse*(ctx: PContext; info: TLineInfo; sym: PSym) =
   ## Check symbol uses match their definition's style.
   if {optStyleHint, optStyleError} * ctx.config.globalOptions != {} and # ignore if styleChecks are off
      hintName in ctx.config.notes and # ignore if name checks are not requested
-     ctx.config.belongsToProjectPackage(sym) and # ignore foreign packages
      sym.kind != skTemp and # ignore temporary variables created by the compiler
      sym.name.s[0] in Letters and # ignore operators TODO: what about unicode symbols???
      sfAnon notin sym.flags: # ignore temporary variables created by the compiler
-    styleCheckUseImpl(ctx.config, info, sym)
+    if ctx.config.belongsToProjectPackage(sym):
+      styleCheckUseImpl(ctx.config, info, sym)
+    else:
+      styleCheckUsagesMatchFirstUse(ctx, info, sym)
 
 proc checkPragmaUseImpl(conf: ConfigRef; info: TLineInfo; w: TSpecialWord; pragmaName: string) =
   let wanted = $w
diff --git a/compiler/semdata.nim b/compiler/semdata.nim
index 363b7e5a4b2c1..e1b8fd0e38be0 100644
--- a/compiler/semdata.nim
+++ b/compiler/semdata.nim
@@ -162,6 +162,7 @@ type
     lastTLineInfo*: TLineInfo
     sideEffects*: Table[int, seq[(TLineInfo, PSym)]] # symbol.id index
     inUncheckedAssignSection*: int
+    firstUsageOfForeignSym*: Table[int, tuple[ident: string, info: TLineInfo]] # (symbol.id, ...)
 
 template config*(c: PContext): ConfigRef = c.graph.config
 
diff --git a/tests/stylecheck/thint.nim b/tests/stylecheck/thint.nim
index c19aac1b89b35..669eb40b0e04c 100644
--- a/tests/stylecheck/thint.nim
+++ b/tests/stylecheck/thint.nim
@@ -41,3 +41,8 @@ proc generic_proc*[T] {.no_destroy, userPragma.} = #[tt.Hint
             ^ 'snakeCase' should be: 'snake_case' [let declared in thint.nim(28, 7)] [Name] ]#
 
 generic_proc[int]()
+
+# Test that foreign symbols usages are consistent within a module:
+discard host_os # `system.hostOS`
+discard hostos #[tt.Hint
+        ^ 'hostos' should be: 'host_os' [first used at thint.nim(46, 9)] [Name] ]#