fixes #21263; consider all candidates for concept matches (#21265)

compiler/concepts.nim

@@ -274,7 +274,7 @@ proc matchSym(c: PContext; candidate: PSym, n: PNode; m: var MatchCon): bool =
 proc matchSyms(c: PContext, n: PNode; kinds: set[TSymKind]; m: var MatchCon): bool =
   ## Walk the current scope, extract candidates which the same name as 'n[namePos]',
   ## 'n' is the nkProcDef or similar from the concept that we try to match.
-  let candidates = searchInScopesFilterBy(c, n[namePos].sym.name, kinds)
+  let candidates = searchInScopesAllCandidatesFilterBy(c, n[namePos].sym.name, kinds)
   for candidate in candidates:
     #echo "considering ", typeToString(candidate.typ), " ", candidate.magic
     m.magic = candidate.magic

compiler/lookups.nim

@@ -228,6 +228,23 @@ proc debugScopes*(c: PContext; limit=0, max = int.high) {.deprecated.} =
     if i == limit: return
     inc i
 
+proc searchInScopesAllCandidatesFilterBy*(c: PContext, s: PIdent, filter: TSymKinds): seq[PSym] =
+  result = @[]
+  for scope in allScopes(c.currentScope):
+    var ti: TIdentIter
+    var candidate = initIdentIter(ti, scope.symbols, s)
+    while candidate != nil:
+      if candidate.kind in filter:
+        result.add candidate
+      candidate = nextIdentIter(ti, scope.symbols)
+
+  if result.len == 0:
+    var marked = initIntSet()
+    for im in c.imports.mitems:
+      for s in symbols(im, marked, s, c.graph):
+        if s.kind in filter:
+          result.add s
+
 proc searchInScopesFilterBy*(c: PContext, s: PIdent, filter: TSymKinds): seq[PSym] =
   result = @[]
   block outer:

tests/concepts/tconcepts_issues.nim

@@ -27,6 +27,8 @@ false
 true
 -1
 Meow
+10 0.0
+1 2.0
 '''
 joinable: false
 """
@@ -500,3 +502,26 @@ var r, b: Fp2[6, uint64]
 
 prod(r, b)
 
+
+block: # bug #21263
+  type
+    DateDayFraction = concept # no T, an atom
+      proc date(a: Self): int
+      proc fraction(b: Self): float
+    Date = distinct int
+    DateDayFractionImpl = object
+      date : int
+      fraction : float
+
+  proc date(a: Date): int = a.int
+  proc fraction(a:Date): float = 0.0
+
+  proc date(a: DateDayFractionImpl): int = a.date
+  proc fraction(b: DateDayFractionImpl): float = b.fraction
+
+
+  proc print(a: DateDayFraction) =
+    echo a.date, " ", a.fraction
+
+  print(10.Date) # ok
+  print(DateDayFractionImpl(date: 1, fraction: 2))  # error