Sema: Fix source ranges for string literals in TypeRefinementContext.

Since string literals are only a single token from the perspective of the
parser, the source range for a pattern binding decl that is initialized with a
string literal expression only extends to the beginning of the string literal.
To ensure the TypeRefinementContext for a pattern binding decl includes the
entire contents of the init expression we must calculate the character source
range of the decl instead.

Resolves rdar://110952225 and #77050.

Author: tshortli

lib/Sema/TypeCheckAvailability.cpp

@@ -782,10 +782,12 @@ class TypeRefinementContextBuilder : private ASTWalker {
     // it.
     assert(D->getSourceRange().isValid());
 
+    auto &Context = D->getASTContext();
+    SourceRange Range;
     if (auto *storageDecl = dyn_cast<AbstractStorageDecl>(D)) {
       // Use the declaration's availability for the context when checking
       // the bodies of its accessors.
-      SourceRange Range = storageDecl->getSourceRange();
+      Range = storageDecl->getSourceRange();
 
       // HACK: For synthesized trivial accessors we may have not a valid
       // location for the end of the braces, so in that case we will fall back
@@ -797,11 +799,12 @@ class TypeRefinementContextBuilder : private ASTWalker {
       if (BracesRange.isValid()) {
         Range.widen(BracesRange);
       }
-
-      return Range;
+    } else {
+      Range = D->getSourceRangeIncludingAttrs();
     }
 
-    return D->getSourceRangeIncludingAttrs();
+    Range.End = Lexer::getLocForEndOfToken(Context.SourceMgr, Range.End);
+    return Range;
   }
 
   // Creates an implicit decl TRC specifying the deployment
@@ -827,7 +830,7 @@ class TypeRefinementContextBuilder : private ASTWalker {
       if (auto bodyStmt = tlcd->getBody()) {
         pushDeclBodyContext(
             tlcd, {{bodyStmt, createImplicitDeclContextForDeploymentTarget(
-                                  tlcd, tlcd->getSourceRange())}});
+                                  tlcd, refinementSourceRangeForDecl(tlcd))}});
       }
       return;
     }

test/Sema/availability_refinement_contexts.swift

@@ -299,6 +299,18 @@ var someComputedGlobalVar: Int {
   set { }
 }
 
+// CHECK-NEXT: {{^}}  (decl_implicit version=50 decl=interpolated
+// CHECK-NEXT: {{^}}    (decl_implicit version=50 decl=string
+
+func testStringInterpolation() {
+  let interpolated = """
+    \([""].map {
+      let string = $0
+      return string
+    })
+    """
+}
+
 // CHECK-NEXT: {{^}}  (decl version=51 decl=FinalDecl
 
 @available(OSX 51, *)