OpenGL and Vulkan examples; ptr(int)/int(ptr); trailing commas in calls; drop .fn hint

- examples/opengl.fch: OpenGL 3.3 core, shaders, VAO/VBO, a spinning triangle (checked offscreen)
- examples/vulkan.fch: instance, GPUs with properties/memory/queues, logical device and queue
- ptr(n) and int(p) conversions for C APIs that pass offsets as pointers
- .ptr works on string literals; a comma after the last call argument is allowed
- a missing header included by an imported header is now named in the error
- the old .fn extension hint is gone (Finch is new, there are no old files)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -105,6 +105,8 @@ Pick the guide that fits you:
 | [`examples/types.fch`](examples/types.fch) | sized numbers and pointers |
 | [`examples/c_import.fch`](examples/c_import.fch) | `printf`, `math.h`, `malloc`/`free`, `stderr` |
 | [`examples/window.fch`](examples/window.fch) | a GLFW + OpenGL window |
+| [`examples/opengl.fch`](examples/opengl.fch) | modern OpenGL 3.3: shaders, buffers, a spinning triangle |
+| [`examples/vulkan.fch`](examples/vulkan.fch) | Vulkan: list the GPUs, their memory and queues, create a device |
 | [`examples/raylib.fch`](examples/raylib.fch) | raylib with C structs by value |
 | [`examples/llvm.fch`](examples/llvm.fch) | Finch building LLVM IR through the LLVM-C API |
 | [`boot/`](boot/) | the Finch compiler, written in Finch |

README.pl.md

@@ -105,6 +105,8 @@ Wybierz przewodnik dla siebie:
 | [`examples/types.fch`](examples/types.fch) | liczby z rozmiarem i wskaźniki |
 | [`examples/c_import.fch`](examples/c_import.fch) | `printf`, `math.h`, `malloc`/`free`, `stderr` |
 | [`examples/window.fch`](examples/window.fch) | okno GLFW + OpenGL |
+| [`examples/opengl.fch`](examples/opengl.fch) | nowoczesny OpenGL 3.3: shadery, bufory, obracający się trójkąt |
+| [`examples/vulkan.fch`](examples/vulkan.fch) | Vulkan: lista kart graficznych, ich pamięć i kolejki, tworzenie urządzenia |
 | [`examples/raylib.fch`](examples/raylib.fch) | raylib ze strukturami C przez wartość |
 | [`examples/llvm.fch`](examples/llvm.fch) | Finch budujący LLVM IR przez API LLVM-C |
 | [`boot/`](boot/) | kompilator Fincha napisany w Finchu |

boot/main.fch

@@ -42,11 +42,6 @@ struct Loader {
 fn load(ptr[Loader] l, str path, str module) {
     if !file_exists(path) {
         if module.len > 0 {
-            old := path.sub(0, path.len - 4) + ".fn"
-            if file_exists(old) {
-                print("error: found " + old + ", but Finch files now end in .fch: rename it to " + path)
-                exit(1)
-            }
             print("error: can't find the module '" + module + "' (looked for " + path + ")")
         } else {
             print("error: can't open '" + path + "'")

boot/parser.fch

@@ -385,7 +385,7 @@ fn parseArgs(ptr[Parser] p, ptr[ast.Node] call) {
     expect(p, "(", "'('")
     p.depth += 1
     if !at(p, ")") {
-        while true {
+        while !at(p, ")") {
             name := ""
             if at(p, "ident") && peekKind(p, 1) == ":" {
                 name = next(p).text

docs/en/for-engineers.md

@@ -160,7 +160,7 @@ unary       = ( "-" | "!" | "~" ) unary | postfix ;
 postfix     = primary { "." IDENT [ args ] | "[" expr "]" } ;
 primary     = INT | FLOAT | STRING | CHAR | "true" | "false" | "null"
             | IDENT [ args ] | "(" expr ")" | "[" [ expr { "," expr } [","] ] "]" ;
-args        = "(" [ arg { "," arg } ] ")" ;  arg = [ IDENT ":" ] expr ;
+args        = "(" [ arg { "," arg } [","] ] ")" ;  arg = [ IDENT ":" ] expr ;
 ```
 
 **Statement termination.** After a statement, `endOfStatement()` requires `}`, end of file, or a token
@@ -343,6 +343,7 @@ int + float → float; f32 + f64 → f64. There is no C integer promotion: `u8 +
 | `[]u8`/`[]char` → str | `finch_str_from_bytes` |
 | ptr → str | `finch_str_from_c` (borrowed, `cap = -1`) |
 | ptr ↔ ptr | nothing |
+| int → ptr / ptr → int | `inttoptr` / `ptrtoint` |
 
 ### Comparisons
 

docs/en/for-technicians.md

@@ -244,6 +244,8 @@ str(42)          // "42"  (also floats, bools, chars; str([]u8) turns bytes into
 int("42")        // 42    (stops the program if the text isn't a number)
 float("2.5")     // 2.5
 ptr(p)           // a typed pointer as an untyped one
+ptr(16)          // a number as a pointer (C APIs that pass offsets as pointers, like OpenGL)
+int(p)           // a pointer as a number (its address)
 str(p)           // a C char pointer as text
 ```
 
@@ -345,6 +347,7 @@ fn no_result(str message) {       // no "->": returns nothing
   To change the caller's variable, pass a pointer: see [Pointers](#14-pointers).
 - A function with `-> type` must return a value on every path. Finch checks this.
 - A function cannot be defined inside another function.
+- Long calls can be split over several lines inside the brackets; a comma after the last argument is fine.
 
 ---
 
@@ -604,6 +607,30 @@ fn main() {
 To give C a function to call back (like `qsort`'s comparator), use `addr(myFunction)`.
 Its parameters must be C types (numbers, pointers, C structs).
 
+### Graphics: OpenGL and Vulkan
+
+Both work directly; `examples/opengl.fch` and `examples/vulkan.fch` are complete programs.
+
+- **OpenGL 3+** on Linux: the modern functions (`glCreateShader`, `glGenVertexArrays`, …) are only
+  declared when `GL_GLEXT_PROTOTYPES` is defined. Finch can't define C macros, so put the includes in a
+  tiny header next to your program and import that:
+
+  ```c
+  // opengl.h
+  #define GL_GLEXT_PROTOTYPES
+  #include <GL/gl.h>
+  #include <GL/glext.h>
+  #include <GLFW/glfw3.h>
+  ```
+
+  Then `import "opengl.h"`, `link "glfw"`, `link "GL"`. Out-parameters use `addr(...)`
+  (`glGenBuffers(1, addr(vbo))`), buffer data uses `.ptr` (`vertices.ptr`), and byte offsets use
+  `ptr(...)` (`glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, stride, ptr(8))`).
+- **Vulkan**: `import "vulkan/vulkan.h"` and `link "vulkan"`. Vulkan's create-info structs are built with
+  named fields (missing ones are zero), handles are `ptr`, and lists come from the usual "call twice"
+  pattern: once for the count, once with `list.ptr` after `list.resize(count)`. Function-like macros such as
+  `VK_MAKE_API_VERSION` aren't available; compute the number instead (`1 << 22` is Vulkan 1.0).
+
 ### What does not work yet
 
 - C **unions** by value, and structs with **bit fields** by value (pointers to them work).
@@ -680,7 +707,7 @@ Finch/
 ├── src/            the compiler (C++)
 ├── runtime/        finch_rt.c: the small runtime (text, arrays, input, files)
 ├── boot/           the Finch compiler written in Finch (see the engineers' guide)
-├── examples/       hello, tour, types, structs, todo, guess, c_import, window, raylib, llvm
+├── examples/       hello, tour, types, structs, todo, guess, c_import, window, opengl, vulkan, raylib, llvm
 ├── tests/
 │   ├── run/        programs + the exact output they must print (.out), input (.in)
 │   ├── fail/       programs that must fail, with the expected error in line 1

docs/pl/dla-inzynierow.md

@@ -160,7 +160,7 @@ unary       = ( "-" | "!" | "~" ) unary | postfix ;
 postfix     = primary { "." IDENT [ args ] | "[" expr "]" } ;
 primary     = INT | FLOAT | STRING | CHAR | "true" | "false" | "null"
             | IDENT [ args ] | "(" expr ")" | "[" [ expr { "," expr } [","] ] "]" ;
-args        = "(" [ arg { "," arg } ] ")" ;  arg = [ IDENT ":" ] expr ;
+args        = "(" [ arg { "," arg } [","] ] ")" ;  arg = [ IDENT ":" ] expr ;
 ```
 
 **Koniec instrukcji.** Po instrukcji `endOfStatement()` wymaga `}`, końca pliku albo tokenu
@@ -347,6 +347,7 @@ Nie ma promocji całkowitych z C: `u8 + u8` zostaje `u8`.
 | `[]u8`/`[]char` → str | `finch_str_from_bytes` |
 | ptr → str | `finch_str_from_c` (pożyczony, `cap = -1`) |
 | ptr ↔ ptr | nic |
+| int → ptr / ptr → int | `inttoptr` / `ptrtoint` |
 
 ### Porównania
 

docs/pl/dla-technikow.md

@@ -244,6 +244,8 @@ str(42)          // "42"  (też float, bool, char; str([]u8) zamienia bajty na t
 int("42")        // 42    (zatrzymuje program, jeśli tekst nie jest liczbą)
 float("2.5")     // 2.5
 ptr(p)           // wskaźnik z typem jako wskaźnik bez typu
+ptr(16)          // liczba jako wskaźnik (API C, które przekazują przesunięcia jako wskaźniki, np. OpenGL)
+int(p)           // wskaźnik jako liczba (jego adres)
 str(p)           // wskaźnik na znaki z C jako tekst
 ```
 
@@ -346,6 +348,7 @@ fn bez_wyniku(str wiadomosc) {    // bez "->": nic nie zwraca
   Żeby zmienić zmienną wywołującego, przekaż wskaźnik, zobacz [Wskaźniki](#14-wskaźniki).
 - Funkcja z `-> typ` musi zwrócić wartość na każdej ścieżce. Finch to sprawdza.
 - Funkcji nie można definiować wewnątrz innej funkcji.
+- Długie wywołania możesz rozbić na kilka linijek wewnątrz nawiasów; przecinek po ostatnim argumencie jest dozwolony.
 
 ---
 
@@ -605,6 +608,30 @@ fn main() {
 Żeby dać C funkcję do wywołania zwrotnego (np. porównywarkę dla `qsort`), użyj `addr(mojaFunkcja)`.
 Jej parametry muszą być typami C (liczby, wskaźniki, struktury C).
 
+### Grafika: OpenGL i Vulkan
+
+Oba działają bezpośrednio; `examples/opengl.fch` i `examples/vulkan.fch` to kompletne programy.
+
+- **OpenGL 3+** na Linuksie: nowoczesne funkcje (`glCreateShader`, `glGenVertexArrays`, …) są deklarowane
+  dopiero po zdefiniowaniu `GL_GLEXT_PROTOTYPES`. Finch nie definiuje makr C, więc dołączenia umieść w małym
+  nagłówku obok programu i zaimportuj go:
+
+  ```c
+  // opengl.h
+  #define GL_GLEXT_PROTOTYPES
+  #include <GL/gl.h>
+  #include <GL/glext.h>
+  #include <GLFW/glfw3.h>
+  ```
+
+  Potem `import "opengl.h"`, `link "glfw"`, `link "GL"`. Parametry wyjściowe przekazujesz przez `addr(...)`
+  (`glGenBuffers(1, addr(vbo))`), dane bufora przez `.ptr` (`vertices.ptr`), a przesunięcia w bajtach przez
+  `ptr(...)` (`glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, stride, ptr(8))`).
+- **Vulkan**: `import "vulkan/vulkan.h"` i `link "vulkan"`. Struktury „create info” budujesz z nazwanymi polami
+  (brakujące są zerami), uchwyty to `ptr`, a listy pobierasz typowym wzorcem „dwóch wywołań”: raz po liczbę,
+  raz z `lista.ptr` po `lista.resize(liczba)`. Makra-funkcje, jak `VK_MAKE_API_VERSION`, nie są dostępne;
+  policz liczbę sam (`1 << 22` to Vulkan 1.0).
+
 ### Co jeszcze nie działa
 
 - **Unie** C przez wartość i struktury z **polami bitowymi** przez wartość (wskaźniki do nich działają).
@@ -682,7 +709,7 @@ Finch/
 ├── src/            kompilator (C++)
 ├── runtime/        finch_rt.c: mała biblioteka uruchomieniowa (teksty, tablice, wejście, pliki)
 ├── boot/           kompilator Fincha napisany w Finchu (zobacz przewodnik dla inżynierów)
-├── examples/       hello, tour, types, structs, todo, guess, c_import, window, raylib, llvm
+├── examples/       hello, tour, types, structs, todo, guess, c_import, window, opengl, vulkan, raylib, llvm
 ├── tests/
 │   ├── run/        programy + dokładny wynik (.out) i wejście (.in)
 │   ├── fail/       programy, które muszą się nie udać, z oczekiwanym błędem w 1. linijce

examples/opengl.fch

@@ -0,0 +1,105 @@
+// Modern OpenGL (3.3 core): a spinning, colorful triangle drawn with shaders.
+// Shows structs of numbers going to the GPU, C out-parameters with addr(), and
+// pointers made from numbers with ptr(...). Needs GLFW and OpenGL (in shell.nix).
+import "opengl.h"
+link "glfw"
+link "GL"
+
+fn compileShader(u32 kind, str source) -> u32 {
+    shader := glCreateShader(kind)
+    src := source.ptr
+    glShaderSource(shader, 1, addr(src), null)
+    glCompileShader(shader)
+    i32 ok
+    glGetShaderiv(shader, GL_COMPILE_STATUS, addr(ok))
+    if ok == 0 {
+        log := " ".repeat(1024)
+        glGetShaderInfoLog(shader, 1024, null, log)
+        print("shader error:", str(log.ptr))
+        exit(1)
+    }
+    return shader
+}
+
+fn makeProgram() -> u32 {
+    vertex := "#version 330 core\n" +
+        "layout(location = 0) in vec2 pos;\n" +
+        "layout(location = 1) in vec3 color;\n" +
+        "uniform float time;\n" +
+        "out vec3 vColor;\n" +
+        "void main() {\n" +
+        "    float c = cos(time), s = sin(time);\n" +
+        "    gl_Position = vec4(c * pos.x - s * pos.y, s * pos.x + c * pos.y, 0.0, 1.0);\n" +
+        "    vColor = color;\n" +
+        "}\n"
+    fragment := "#version 330 core\n" +
+        "in vec3 vColor;\n" +
+        "out vec4 outColor;\n" +
+        "void main() { outColor = vec4(vColor, 1.0); }\n"
+
+    vs := compileShader(GL_VERTEX_SHADER, vertex)
+    fs := compileShader(GL_FRAGMENT_SHADER, fragment)
+    program := glCreateProgram()
+    glAttachShader(program, vs)
+    glAttachShader(program, fs)
+    glLinkProgram(program)
+    glDeleteShader(vs)
+    glDeleteShader(fs)
+    return program
+}
+
+fn main() {
+    if glfwInit() == 0 {
+        print("could not start GLFW")
+        return
+    }
+    defer glfwTerminate()
+    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3)
+    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3)
+    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE)
+
+    window := glfwCreateWindow(800, 600, "Finch + OpenGL", null, null)
+    if window == null {
+        print("could not open a window (does your GPU support OpenGL 3.3?)")
+        return
+    }
+    glfwMakeContextCurrent(window)
+    glfwSwapInterval(1)
+    print("OpenGL", str(glGetString(GL_VERSION)), "on", str(glGetString(GL_RENDERER)))
+
+    // x, y, r, g, b for each corner
+    []f32 vertices = [
+         0.0,  0.6,   1.0, 0.48, 0.1,
+        -0.6, -0.4,   0.2, 0.6,  1.0,
+         0.6, -0.4,   0.6, 1.0,  0.4,
+    ]
+    u32 vao
+    u32 vbo
+    glGenVertexArrays(1, addr(vao))
+    glGenBuffers(1, addr(vbo))
+    glBindVertexArray(vao)
+    glBindBuffer(GL_ARRAY_BUFFER, vbo)
+    glBufferData(GL_ARRAY_BUFFER, vertices.len * 4, vertices.ptr, GL_STATIC_DRAW)
+    i32 stride = 5 * 4
+    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, stride, ptr(0))
+    glEnableVertexAttribArray(0)
+    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, stride, ptr(2 * 4))
+    glEnableVertexAttribArray(1)
+
+    program := makeProgram()
+    timeLoc := glGetUniformLocation(program, "time")
+
+    while glfwWindowShouldClose(window) == 0 {
+        glClearColor(0.106, 0.122, 0.165, 1.0)
+        glClear(GL_COLOR_BUFFER_BIT)
+        glUseProgram(program)
+        glUniform1f(timeLoc, f32(glfwGetTime()))
+        glDrawArrays(GL_TRIANGLES, 0, 3)
+        glfwSwapBuffers(window)
+        glfwPollEvents()
+    }
+
+    glDeleteBuffers(1, addr(vbo))
+    glDeleteVertexArrays(1, addr(vao))
+    glDeleteProgram(program)
+}

examples/opengl.h

@@ -0,0 +1,6 @@
+// Everything examples/opengl.fch needs from C. GL_GLEXT_PROTOTYPES makes <GL/glext.h>
+// declare the modern (OpenGL 3+) functions, which Linux's libGL exports directly.
+#define GL_GLEXT_PROTOTYPES
+#include <GL/gl.h>
+#include <GL/glext.h>
+#include <GLFW/glfw3.h>

examples/vulkan.fch

@@ -0,0 +1,137 @@
+// Vulkan from Finch: create an instance, list every GPU with its properties, memory and
+// queues, then create a logical device and get a graphics queue. No window needed.
+// Shows big C structs (with arrays of structs inside), out-parameters and Vulkan handles.
+// Needs the Vulkan loader and headers (in shell.nix) and a Vulkan driver.
+import "vulkan/vulkan.h"
+link "vulkan"
+
+fn check(i32 result, str what) {
+    if result != VK_SUCCESS {
+        print(what, "failed with VkResult", result)
+        exit(1)
+    }
+}
+
+fn version(u32 v) -> str {
+    return str(v >> 22) + "." + str((v >> 12) & 0x3FF) + "." + str(v & 0xFFF)
+}
+
+fn deviceType(i32 t) -> str {
+    if t == VK_PHYSICAL_DEVICE_TYPE_DISCRETE_GPU {
+        return "discrete GPU"
+    }
+    if t == VK_PHYSICAL_DEVICE_TYPE_INTEGRATED_GPU {
+        return "integrated GPU"
+    }
+    if t == VK_PHYSICAL_DEVICE_TYPE_VIRTUAL_GPU {
+        return "virtual GPU"
+    }
+    if t == VK_PHYSICAL_DEVICE_TYPE_CPU {
+        return "CPU (software)"
+    }
+    return "other"
+}
+
+fn queueFlags(u32 f) -> str {
+    []str parts
+    if f & VK_QUEUE_GRAPHICS_BIT != 0 {
+        parts.push("graphics")
+    }
+    if f & VK_QUEUE_COMPUTE_BIT != 0 {
+        parts.push("compute")
+    }
+    if f & VK_QUEUE_TRANSFER_BIT != 0 {
+        parts.push("transfer")
+    }
+    if f & VK_QUEUE_SPARSE_BINDING_BIT != 0 {
+        parts.push("sparse")
+    }
+    if f & VK_QUEUE_VIDEO_DECODE_BIT_KHR != 0 {
+        parts.push("video decode")
+    }
+    if f & VK_QUEUE_VIDEO_ENCODE_BIT_KHR != 0 {
+        parts.push("video encode")
+    }
+    if parts.len == 0 {
+        return "other"
+    }
+    return parts.join(", ")
+}
+
+fn main() {
+    app := VkApplicationInfo(
+        sType: VK_STRUCTURE_TYPE_APPLICATION_INFO,
+        pApplicationName: "Finch".ptr,
+        applicationVersion: 1,
+        pEngineName: "none".ptr,
+        apiVersion: 1 << 22,              // Vulkan 1.0
+    )
+    info := VkInstanceCreateInfo(sType: VK_STRUCTURE_TYPE_INSTANCE_CREATE_INFO, pApplicationInfo: addr(app))
+    ptr instance
+    check(vkCreateInstance(addr(info), null, addr(instance)), "vkCreateInstance")
+    defer vkDestroyInstance(instance, null)
+
+    u32 count
+    check(vkEnumeratePhysicalDevices(instance, addr(count), null), "counting GPUs")
+    []ptr gpus
+    gpus.resize(count)
+    check(vkEnumeratePhysicalDevices(instance, addr(count), gpus.ptr), "listing GPUs")
+    print("Vulkan found", count, "device(s)")
+
+    for gpu in gpus {
+        VkPhysicalDeviceProperties props
+        vkGetPhysicalDeviceProperties(gpu, addr(props))
+        print()
+        print(str(props.deviceName.ptr))
+        print("  type:", deviceType(props.deviceType))
+        print("  Vulkan " + version(props.apiVersion) + ", driver " + str(props.driverVersion))
+        print("  biggest 2D image:", props.limits.maxImageDimension2D, "px")
+
+        VkPhysicalDeviceMemoryProperties mem
+        vkGetPhysicalDeviceMemoryProperties(gpu, addr(mem))
+        for h in 0..mem.memoryHeapCount {
+            heap := mem.memoryHeaps[h]
+            local := ""
+            if heap.flags & VK_MEMORY_HEAP_DEVICE_LOCAL_BIT != 0 {
+                local = " (on the GPU)"
+            }
+            print("  memory heap " + str(h) + ": " + str(float(heap.size) / 1073741824.0) + " GiB" + local)
+        }
+
+        u32 families
+        vkGetPhysicalDeviceQueueFamilyProperties(gpu, addr(families), null)
+        []VkQueueFamilyProperties queues
+        queues.resize(families)
+        vkGetPhysicalDeviceQueueFamilyProperties(gpu, addr(families), queues.ptr)
+        graphics := -1
+        for q in 0..queues.len {
+            print("  queue family " + str(q) + ": " + str(queues[q].queueCount) + " x " + queueFlags(queues[q].queueFlags))
+            if graphics < 0 && queues[q].queueFlags & VK_QUEUE_GRAPHICS_BIT != 0 {
+                graphics = q
+            }
+        }
+        if graphics < 0 {
+            continue
+        }
+
+        // a logical device with one graphics queue: what a renderer would start from
+        f32 priority = 1.0
+        queueInfo := VkDeviceQueueCreateInfo(
+            sType: VK_STRUCTURE_TYPE_DEVICE_QUEUE_CREATE_INFO,
+            queueFamilyIndex: u32(graphics),
+            queueCount: 1,
+            pQueuePriorities: addr(priority),
+        )
+        deviceInfo := VkDeviceCreateInfo(
+            sType: VK_STRUCTURE_TYPE_DEVICE_CREATE_INFO,
+            queueCreateInfoCount: 1,
+            pQueueCreateInfos: addr(queueInfo),
+        )
+        ptr device
+        check(vkCreateDevice(gpu, addr(deviceInfo), null, addr(device)), "vkCreateDevice")
+        ptr queue
+        vkGetDeviceQueue(device, u32(graphics), 0, addr(queue))
+        print("  created a device and got graphics queue", queue != null)
+        vkDestroyDevice(device, null)
+    }
+}

shell.nix

@@ -10,9 +10,11 @@ pkgs.mkShell {
     ninja
     pkg-config              # finds the right flags for `link "..."`
 
-    # for examples/window.fch and examples/raylib.fch
+    # for the graphics examples (window, opengl, raylib, vulkan)
     glfw
     libGL
     raylib
+    vulkan-headers
+    vulkan-loader
   ];
 }

src/cimport.cpp

@@ -341,8 +341,14 @@ CImports importHeaders(const std::vector<Import> &imports, const std::vector<std
             if (clang_getDiagnosticSeverity(d) >= CXDiagnostic_Error) {
                 std::string msg = str(clang_getDiagnosticSpelling(d));
                 clang_disposeDiagnostic(d);
-                if (msg.find("file not found") != std::string::npos)
-                    failAt(im.pos.file, im.pos.line, im.pos.col, "can't find the C header '" + im.path + "'");
+                if (msg.find("file not found") != std::string::npos) {
+                    // "'GL/gl.h' file not found": it may be a header that this one includes
+                    std::string missing = msg.substr(1, msg.find('\'', 1) - 1);
+                    if (missing == im.path)
+                        failAt(im.pos.file, im.pos.line, im.pos.col, "can't find the C header '" + im.path + "'");
+                    failAt(im.pos.file, im.pos.line, im.pos.col, "can't find the C header '" + missing + "', which '" + im.path +
+                                                                     "' includes (is its library's development package installed?)");
+                }
                 failAt(im.pos.file, im.pos.line, im.pos.col, "C header '" + im.path + "' has an error: " + msg);
             }
             clang_disposeDiagnostic(d);

src/codegen.cpp

@@ -758,7 +758,9 @@ LRef Codegen::member(const MemberExpr &m, bool forWrite) {
             if (!obj.isPlace) release(obj.val);
             return {false, {}, {len, FType::I64}};
         }
-        if (!obj.isPlace && obj.val.fresh) failAt(p.file, p.line, p.col, ".ptr of a temporary value would point to freed memory");
+        // a literal lives as long as the program; other temporaries are freed right after this expression
+        if (!obj.isPlace && obj.val.fresh && !isa<Constant>(obj.val.v))
+            failAt(p.file, p.line, p.col, ".ptr of a temporary value would point to freed memory");
         FType pt = t.kind == FType::Str ? FType::ptrTo(FType::Char) : FType::ptrTo(*t.elem);
         return {false, {}, {t.kind == FType::Str ? cstr(v) : b.CreateExtractValue(v, 0), pt}};
     }

src/codegen_builtins.cpp

@@ -441,6 +441,8 @@ Value_ Codegen::convert(const FType &to, const std::vector<ExprPtr> &args, Pos,
     }
     if (to.kind == FType::Bool && from.isInt()) return {b.CreateICmpNE(v.v, ConstantInt::get(ty(from), 0)), to};
     if (to.isPtr() && (from.isPtr() || from.kind == FType::Null)) return {v.v, to};
+    if (to.isPtr() && from.isInt()) return {b.CreateIntToPtr(intCast(v.v, from, FType::U64), b.getPtrTy()), to};  // an address or offset for C
+    if (to.isInt() && from.isPtr()) return {b.CreatePtrToInt(v.v, ty(to)), to};
     if (to.isPtr() && from.kind == FType::Str) failAt(p.file, p.line, p.col, "use .ptr to get a str's address (it is only valid while the str lives)");
     failAt(p.file, p.line, p.col, "can't turn " + from.show() + " into " + name);
 }

src/main.cpp

@@ -68,12 +68,7 @@ struct Loader {
     void load(const std::string &path, const std::string &module, Pos from) {
         std::string text;
         if (!readFile(path, text)) {
-            if (from.line) {
-                std::string old = path.substr(0, path.size() - 4) + ".fn";
-                if (sys::fs::exists(old))
-                    failAt(from.file, from.line, from.col, "found " + old + ", but Finch files now end in .fch: rename it to " + path);
-                failAt(from.file, from.line, from.col, "can't find the module '" + module + "' (looked for " + path + ")");
-            }
+            if (from.line) failAt(from.file, from.line, from.col, "can't find the module '" + module + "' (looked for " + path + ")");
             std::fprintf(stderr, "error: can't open '%s'\n", path.c_str());
             std::exit(1);
         }

src/parser.cpp

@@ -456,6 +456,7 @@ private:
         parenDepth++;
         if (!at(Tok::RParen)) {
             do {
+                if (at(Tok::RParen)) break;  // a trailing comma is fine
                 std::string name;
                 if (at(Tok::Ident) && peekTok().kind == Tok::Colon) {
                     name = next().text;

tests/fail/old_extension.fch

@@ -1,3 +0,0 @@
-// expect: but Finch files now end in .fch
-import oldmodule
-fn main() {}

tests/fail/oldmodule.fn

@@ -1,2 +0,0 @@
-fn hi() {
-}

tests/run.sh

@@ -38,7 +38,6 @@ for f in run/*.fch; do
 done
 
 for f in fail/*.fch; do
-    grep -q "^// expect:" "$f" || continue
     expect=$(head -1 "$f" | sed -n 's|^// expect: ||p')
     got=$("$FINCH" run "$f" < /dev/null 2>&1)
     status=$?

tests/run/c_pointers.fch

@@ -0,0 +1,22 @@
+import "string.h"
+
+struct Point {
+    int x
+    int y
+}
+
+fn main() {
+    p := Point(
+        x: 1,
+        y: 2,
+    )
+    print(p)
+    c := "finch".ptr
+    print(c[1], strlen("finch"))
+    q := ptr(4096)
+    print(int(q), int(ptr(0)) == 0, q != null)
+    a := [10, 20, 30]
+    address := int(a.ptr)
+    ptr[int] second = ptr(address + 8)
+    print(second.value)
+}

tests/run/c_pointers.out

@@ -0,0 +1,4 @@
+Point(x: 1, y: 2)
+i 5
+4096 true true
+20