static inline C functions (mingw's printf and time), macOS libraries that call their host, lld's missing-library message

- a static inline function in a header is called through a pointer a small C file keeps
  (void *finch_inl_f = &f), built with the program's include folders and cached
- --shared on macOS links with -undefined dynamic_lookup, as a .so does on Linux
- "unable to find library -lx" (lld, MinGW) gives the library-not-found advice
- the language server test shows the index records when alias completion fails

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016GzNP6r8dg6WDxUVZy8wjL

src/cimport.fch

@@ -18,6 +18,7 @@ struct CFunc {
     ast.Type ret
     []ast.Type params
     bool variadic
+    bool inline         // static inline in the header: called through a pointer a small C file keeps (finch_inl_name)
     str unsupported     // non-empty: why Finch can't call it (yet)
 }
 
@@ -535,9 +536,7 @@ fn visit(ptr[Importer] imp, CXCursor c) {
         }
         f := CFunc(name: name, header: imp.header)
         if clang_Cursor_getStorageClass(c) == CX_SC_Static {
-            f.unsupported = "is a static inline C function (it has no code to link against)"
-            imp.out.fns[name] = f
-            return
+            f.inline = true         // mingw's printf and time, header-only helpers
         }
         ft := clang_getCanonicalType(clang_getCursorType(c))
         if ft.kind == CXType_FunctionNoProto {

src/gen.fch

@@ -5086,17 +5086,26 @@ fn callC(ptr[Gen] g, ast.Node c, cimport.CFunc f) -> Val {
             tail = "..."
         }
     }
-    if !g.cdone.contains("f:" + f.name) {
+    callee := "@" + f.name
+    sig := ""
+    if f.variadic {
+        sig = " (" + ptys.join(", ") + tail + ")"
+    }
+    if f.inline {
+        // a static inline function has no symbol: the linker builds a C file with  void *finch_inl_name = &name;
+        if !g.cdone.contains("i:" + f.name) {
+            g.cdone.push("i:" + f.name)
+            g.head.push("@finch_inl_" + f.name + " = external global ptr")
+        }
+        callee = load(g, "ptr", "@finch_inl_" + f.name)
+        sig = " (" + ptys.join(", ") + tail + ")"
+    } else if !g.cdone.contains("f:" + f.name) {
         g.cdone.push("f:" + f.name)
         if !runtimeDeclares(f.name) {
             g.head.push("declare" + retExt + " " + retLL + " @" + f.name + "(" + ptys.join(", ") + tail + ")")
         }
     }
-    sig := ""
-    if f.variadic {
-        sig = " (" + ptys.join(", ") + tail + ")"
-    }
-    text := "call" + retExt + " " + retLL + sig + " @" + f.name + "(" + args.join(", ") + ")"
+    text := "call" + retExt + " " + retLL + sig + " " + callee + "(" + args.join(", ") + ")"
     if ret.kind == "void" {
         emit(g, text)
         releaseAll(g, temps, mark)

src/linker.fch

@@ -98,6 +98,40 @@ fn depsKey([]str files, str flags) -> str {
     return fingerprint2(all.join("\n"))
 }
 
+// "@finch_inl_name = external global ptr" in the IR -> a C file (in the cache) that defines them; "" if none
+fn inlineFile(str ir, cimport.CImports ci) -> str {
+    []str headers
+    []str lines
+    for line in ir.split("\n") {
+        if line.starts_with("@finch_inl_") && line.ends_with(" = external global ptr") {
+            name := line.sub(11, line.find(" = "))
+            h := ci.fns[name].header
+            if !headers.contains(h) {
+                headers.push(h)
+            }
+            lines.push("void *finch_inl_" + name + " = (void *)&" + name + ";")
+        }
+    }
+    if lines.len == 0 {
+        return ""
+    }
+    []str src
+    for h in headers {
+        src.push("#include \"" + h + "\"")
+    }
+    for l in lines {
+        src.push(l)
+    }
+    text := src.join("\n") + "\n"
+    dir := host.cacheDir() + "/c"
+    host.makeDirs(dir)
+    path := dir + "/inline_" + fingerprint2(text) + ".c"
+    if !file_exists(path) {
+        write_file(path, text)
+    }
+    return path
+}
+
 // A C file of the program (link "x.c"), built once and kept until it or a header it includes changes.
 fn cObject(str src, str cc, str flags, platform.Target tg, str log) -> str! {
     dir := host.cacheDir() + "/c"
@@ -225,6 +259,8 @@ fn linkFailed(str output, cimport.CImports ci, platform.Target tg) -> int {
             missing.add(between(l, "unresolved external symbol ", " \n\r"))
         } else if l.contains("cannot find -l") {
             libs.add(between(l, "cannot find -l", ": \n\r"))
+        } else if l.contains("unable to find library -l") {
+            libs.add(between(l, "unable to find library -l", ": \n\r"))         // lld (MinGW)
         } else if l.contains("library not found for -l") {
             libs.add(between(l, "library not found for -l", ": \n\r"))
         } else if l.contains("ld: library '") {
@@ -368,6 +404,20 @@ fn build(Build b, platform.Target tg, cimport.CImports ci) -> int {
         }
     }
     cmd := linkWith + " " + quote(obj) + " " + quote(rtobj) + " -o " + quote(b.out)
+    // static inline C functions the program calls: a C file that keeps a pointer to each
+    inl := inlineFile(b.ir, ci)
+    if inl.len > 0 {
+        pic := " -fPIC"
+        if tg.windows {
+            pic = ""
+        }
+        o := cObject(inl, cc, " -O2" + pic + b.cflags, tg, log) or {
+            print(err)
+            host.remove(log)
+            return 1
+        }
+        cmd = cmd + " " + quote(o)
+    }
     if !tg.msvc {
         cmd = cmd + " -lm"
     }
@@ -384,7 +434,7 @@ fn build(Build b, platform.Target tg, cimport.CImports ci) -> int {
     }
     if b.shared {
         if tg.darwin {
-            cmd = cmd + " -dynamiclib"
+            cmd = cmd + " -dynamiclib -undefined dynamic_lookup"     // like a .so: the host's functions are found when it is loaded
         } else {
             cmd = cmd + " -shared"
         }

src/main.fch

@@ -495,8 +495,8 @@ fn main([]str args) -> int {
         extra = extra + " -g"      // or clang drops the debug info that is in the IR
     }
     []str cflagList
-    for d in extraDirs {
-        cflagList.push(" -I" + linker.quote(d))
+    for d in dirs {
+        cflagList.push(" -I" + linker.quote(d))      // also the program's own folders (its headers, for inline C functions)
     }
     cflagList.push(cflags)
     if linker.build(linker.Build(out: out, ir: ir, rt: rt, opt: opt, extra: extra, shared: shared, links: links, name: absolute(file), cflags: cflagList.join(""), ldflags: ldflags), tg, ci) != 0 {